JP2021125836A - Imaging device and electronic apparatus - Google Patents

Abstract

To provide an imaging device that can suppress the variation in amplitude range of a signal line in a near-end part pixel that is near and a far-end part pixel that is far relative to a readout circuit that reads out a signal.SOLUTION: An imaging device includes a pixel array part including a readout pixel 20 where signal readout is performed and a reference pixel 30 where signal readout is not performed, a constant-current source 52 connected to source electrodes of an amplification transistor of the readout pixel and an amplification transistor of the reference pixel, and a current mirror circuit 51 that supplies the signal current according to the reference current output from the reference pixel to the readout pixel. The amplification transistor of the readout pixel and the amplification transistor of the reference pixel form a differential amplification circuit together with the constant-current source 52 and the current mirror circuit. The current mirror circuit and the constant-current source are disposed to face each other on opposite sides in a pixel column direction with the pixel array part held therebetween.SELECTED DRAWING: Figure 9

Description

The present disclosure relates to imaging devices and electronic devices.

As one of the image pickup devices, there is a differential amplification type image pickup device that reads out the photoelectrically converted signal charge by using a differential amplifier circuit (see, for example, Patent Document 1). In the differential amplifier type imaging device, a differential amplifier circuit is configured by using a read pixel (selected pixel) in which a signal is read and a reference pixel in which a signal is not read, and the differential amplifier circuit is used. The signal of the read pixel is differentially read by using it as a pixel read circuit. Since the differential amplifier type image pickup device has a larger amplification factor than the case where a circuit other than the differential amplifier circuit, for example, a source follower circuit is used as the pixel readout circuit, it is possible to read out the signal with high conversion efficiency. ..

Japanese Unexamined Patent Publication No. 2018-182496

In the image pickup apparatus, the reading method for reading a signal from each pixel of the pixel array unit includes a so-called one-sided reading method in which a reading circuit is arranged on one side in the pixel array direction with respect to the pixel array unit and reading is performed. There is a so-called double-sided reading method in which reading circuits are arranged on both sides in the column direction to perform reading. In the case of the one-sided readout method, the distance of the current path flowing through the signal line in the pixel array section differs greatly between the near-end pixel that is close in distance and the far-end pixel that is far away from the reading circuit that reads the signal. Along with this, there is a problem that the amplitude range of the signal line between the near-end pixel and the far-end pixel varies.

The present disclosure describes an image pickup device capable of suppressing variation in the amplitude range of a signal line between a near-end pixel close to a distance and a far-end pixel far away from a reading circuit for reading a signal, and the image pickup device. The purpose is to provide an electronic device to have.

The imaging apparatus of the present disclosure for achieving the above object is
A pixel array unit in which a read pixel in which a signal is read and a reference pixel in which a signal is not read are arranged.
A constant current source connected to each source electrode of the amplification transistor of the read pixel and the amplification transistor of the reference pixel, and
A current mirror circuit that supplies a signal current corresponding to the reference current output from the reference pixel to the read pixel.
With
The amplifier transistor of the read pixel and the amplifier transistor of the reference pixel form a differential amplifier circuit together with a constant current source and a current mirror circuit.
The current mirror circuit and the constant current source are arranged to face each other on both sides in the pixel row direction with the pixel array portion interposed therebetween.

The electronic device of the present disclosure for achieving the above object has a configuration having an imaging device having the above configuration.

FIG. 1 is a block diagram showing a configuration example of a one-sided readout type image pickup apparatus. FIG. 2 is a block diagram showing a configuration example of a double-sided readout type image pickup apparatus. FIG. 3 is a circuit diagram showing an example of the configuration of the differential amplifier circuit. FIG. 4 is a block diagram showing an arrangement relationship of a pixel, a constant current source, a current mirror circuit, and a column signal processing unit (ADC) in a one-sided readout type imaging device equipped with a differential amplifier circuit. FIG. 5 is a diagram showing a voltage budget of near-end pixels and a voltage budget of far-end pixels in a one-sided readout type image pickup apparatus. FIG. 6 is a diagram illustrating magnetic field noise. FIG. 7 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the first embodiment, and a current path in the differential mode. FIG. 8 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the first embodiment, and a current path in the SF mode. FIG. 9 is a circuit diagram showing an example of a circuit configuration in the differential mode in the differential amplification type imaging device according to the first embodiment. FIG. 10 is a circuit diagram showing an example of a circuit configuration in the SF mode in the differential amplification type imaging device according to the first embodiment. FIG. 11 is a block diagram showing a simplified current path of the near-end pixel and the far-end pixel in the differential mode. FIG. 12 is a diagram showing a voltage budget of the near-end pixel and a voltage budget of the far-end pixel in the differential mode in the double-sided readout type image pickup apparatus. FIG. 13 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the second embodiment, and a current path in the differential mode. FIG. 14 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the second embodiment, and a current path in the SF mode. FIG. 15 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the third embodiment, and a current path in the differential mode. FIG. 16 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the third embodiment, and a current path in the SF mode. FIG. 17 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the fourth embodiment, and a current path in the differential mode. FIG. 18 is a circuit diagram showing a connection relationship between the horizontal connection wiring and the horizontal connection switch in the differential amplification type imaging device according to the fourth embodiment. FIG. 19 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the fifth embodiment, and a current path in the differential mode. FIG. 20 is a block diagram showing an arrangement example of a current mirror circuit and a constant current source in the differential amplification type imaging device according to the sixth embodiment, and a current path in the differential mode. FIG. 21 is a circuit diagram showing a connection relationship between the horizontal connection wiring and the horizontal connection switch in the differential mode in the differential amplification type imaging device according to the sixth embodiment. FIG. 22 is a circuit diagram showing a connection relationship of the horizontal connection wiring and the horizontal connection switch in the differential amplification type imaging device according to the sixth embodiment in the SF mode. FIG. 23 is a diagram showing an application example of the technique according to the present disclosure. FIG. 24 is a block diagram showing an outline of a configuration example of an imaging system which is an example of the electronic device of the present disclosure. FIG. 25 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technique according to the present disclosure can be applied. FIG. 26 is a diagram showing an example of an installation position of an imaging unit in a mobile control system.

Hereinafter, embodiments for carrying out the technique of the present disclosure (hereinafter, referred to as “embodiments”) will be described in detail with reference to the drawings. The techniques of the present disclosure are not limited to embodiments. In the following description, the same code will be used for the same element or the element having the same function, and duplicate description will be omitted. The explanation will be given in the following order.
1. 1. Description of the imaging apparatus and electronic device of the present disclosure, and general description 2. Configuration example of a general imaging device 2-1. One-sided readout type image pickup device 2-2. Double-sided readout type image pickup device 2-3. Semiconductor chip structure 2-4. Differential amplification type imaging device 2-5. Configuration example of differential amplifier circuit 2-5-1. Circuit configuration example of read pixel 2-5-2. Circuit configuration example of reference pixel 2-5-3. Configuration example of current mirror circuit 2-6. Variation of amplitude range of signal line potential 2-7. About magnetic field noise 3. Embodiments of the present disclosure 3-1. Example 1 (Example in which a current mirror circuit and a constant current source are arranged face-to-face with a pixel array portion in units of two pixel sequences adjacent to each other).
3-2. Example 2 (Modification of Example 1: An example in which the arrangement relationship between the current mirror circuit and the constant current source with respect to the pixel array unit 11 is alternately inverted for each pixel sequence).
3-3. Example 3 (Example in which the current mirror circuit and the constant current source are arranged face-to-face with the pixel array portion sandwiched between four pixel sequences adjacent to each other as a unit).
3-4. Example 4 (Modification of Example 1: Example of having wiring and a switch for horizontally connecting the reference pixel side between pixel rows)
3-5. Example 5 (Modification of Example 4: An example in which horizontal connection is realized in the lower and upper column readout circuit units for each pixel sequence)
3-6. Example 6 (Modification of Example 5: An example in which each VPX wiring of two adjacent pixel rows is combined into one)
4. Modification example 5. Application example 6. Application examples of the technology according to the present disclosure 6-1. Electronic device of the present disclosure (example of imaging device)
6-2. Application example to mobile body 7. Configuration that can be taken by this disclosure

<Explanation of the image pickup apparatus and electronic device of the present disclosure, in general>
In the imaging apparatus and electronic device of the present disclosure, the current mirror circuit and the constant current source are arranged face-to-face with a pixel array portion in units of a plurality of pixel trains, and preferably two pixels adjacent to each other. It is possible to have a configuration in which the pixels are arranged face-to-face with the pixel array portion in units of columns. Then, the arrangement relationship between the current mirror circuit and the constant current source with respect to the pixel array unit can be configured to be alternately inverted for each pixel sequence. Alternatively, the current mirror circuit and the constant current source can be arranged face-to-face with the pixel array portion interposed therebetween in units of four pixel sequences adjacent to each other.

The imaging apparatus and electronic device of the present disclosure including the above-described preferable configuration may have a configuration having a horizontal connection wiring and a horizontal connection switch for electrically connecting the reference pixel side between pixel rows. Further, column reading circuits are provided on both sides of the pixel array section in the pixel row direction, and wiring and vertical signal lines connecting the pixels and the constant current source are provided extending to the column reading circuits on both sides. At this time, the horizontal connection wiring and the horizontal connection switch may be configured to electrically connect the reference pixel side between the pixel rows in the column readout circuits on both sides. Further, the wiring connecting the pixels and the constant current source can be integrated into one wire between adjacent pixel rows.

Further, the image pickup apparatus and the electronic device of the present disclosure including the above-described preferable configuration have a differential amplifier / read mode by a differential amplifier circuit and a read mode by a source follower circuit, and can switch between the two modes. Can be configured.

<Configuration example of general imaging device>
Prior to explaining the image pickup apparatus of the present disclosure, a configuration example of a general image pickup apparatus will be described. Here, as a general imaging device, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, which is a kind of XY address type imaging device, will be described as an example. A CMOS image sensor is an image sensor made by applying or partially using a CMOS process.

In an imaging device such as a CMOS image sensor, the reading method for reading a signal from each pixel of the pixel array unit includes a one-sided reading method for reading from one side in the pixel array direction with respect to the pixel array unit in which the pixels are arranged, and a pixel array. There is a double-sided reading method that reads from both sides of the direction.

[One-sided readout type imaging device]
FIG. 1 is a block diagram showing a configuration example of a one-sided readout type image pickup apparatus.

The one-sided readout type imaging device 10A includes a pixel array unit 11, a vertical drive unit 12, a column readout circuit unit 13, a column signal processing unit 14, a horizontal drive unit 15, a signal processing unit 16, and a system control unit 17. There is. Then, in the image pickup apparatus 10A, the column readout circuit unit 13, the column signal processing unit 14, and the horizontal drive unit 15 are arranged on one side (for example, the lower side in the figure) in the pixel row direction with respect to the pixel array unit 11. The signal of each pixel 20 of the pixel array unit 11 is read from one side in the pixel row direction.

The pixel array unit 11 is configured by two-dimensionally arranging pixels 20 having a photoelectric conversion unit that generates an amount of light charge according to the amount of incident light in a matrix. _{In the pixel array unit 11, pixel drive lines 111 1 to} 111 _m are wired along the pixel row direction (left-right direction in the figure) for each pixel row with respect to the pixel array of m rows and n columns. _{Further, vertical signal lines 112 1 to 112 n} are wired in the pixel array unit 11 for each pixel row along the pixel row direction (vertical direction in the figure). One end of the pixel drive line 111 is connected to the output end corresponding to each pixel row of the vertical drive unit 12.

The vertical drive unit 12 is a pixel drive unit that is composed of a shift register, an address decoder, and the like, and drives each pixel 20 of the pixel array unit 11 simultaneously for all pixels or in pixel row units. Although the specific configuration of the vertical drive unit 12 is not shown, it has a read scanning system and a sweep scanning system, and under the drive of these scanning systems, batch sweeping and batch transfer are performed. It can be carried out.

The read-out scanning system selectively scans each pixel 20 of the pixel array unit 11 in pixel-row units in order to read a signal from the pixel 20. In the case of row drive (rolling shutter operation), for sweeping, sweep scanning is performed ahead of the read scan performed by the read scan system by the time of the shutter speed. Further, in the case of global exposure (global shutter operation), batch sweeping is performed prior to batch transfer by the time of the shutter speed.

By this sweeping, unnecessary charges are swept out from the photoelectric conversion part of the pixel 20 of the reading line. Then, the so-called electronic shutter operation is performed by sweeping out (resetting) unnecessary charges. Here, the electronic shutter operation refers to an operation of discarding the light charge of the photoelectric conversion unit and starting a new exposure (starting the accumulation of the light charge).

The signal read by the read operation by the read scanning system corresponds to the amount of light incidented after the read operation or the electronic shutter operation immediately before that. In the case of row drive, the period from the read timing by the immediately preceding read operation or the sweep timing by the electronic shutter operation to the read timing by the current read operation is the light charge accumulation period (exposure period) in the pixel 20. .. In the case of global exposure, the period from batch sweeping to batch transfer is the accumulation period (exposure period).

The pixel signal output from each pixel 20 of the pixel row selected by the vertical drive unit 12 is supplied to the column readout circuit unit 13 through each of the vertical signal lines 112. The column readout circuit unit 13 is composed of a current mirror circuit and a constant current source constituting a differential amplifier circuit, an analog-to-digital converter (ADC), and the like, together with a readout pixel and a reference pixel described later, and is provided for each pixel sequence. It has a structure.

The column signal processing unit 14 outputs a pixel signal that is output from each pixel 20 of the selected row through the vertical signal line (VSL) 112 for each pixel column of the pixel array unit 11 and is supplied via the column readout circuit unit 13. On the other hand, a predetermined signal processing is performed, and the pixel signal after the signal processing is temporarily held. As the predetermined signal processing, for example, noise removal processing by Correlated Double Sampling (CDS) and the like can be exemplified.

The horizontal drive unit 15 is composed of a shift register, an address decoder, and the like, and sequentially selects unit circuits corresponding to the pixel strings of the column signal processing unit 14. By the selective scanning by the horizontal drive unit 15, the pixel signals signal-processed by the column signal processing unit 14 are sequentially output to the signal processing unit 16.

The signal processing unit 16 performs various signal processing on the pixel signal output from the column signal processing unit 14, including noise removal processing by, for example, CDS (Correlated Double Sampling).

The system control unit 17 is composed of a timing generator or the like that generates various timing signals, and is a vertical drive unit 12, a column readout circuit unit 13, and a column signal processing unit 14 based on various timing signals generated by the timing generator. , And drive control of the horizontal drive unit 15 and the like.

[Double-sided readout type imaging device]
FIG. 2 is a block diagram showing a configuration example of a double-sided readout type image pickup apparatus.

The two-sided readout type image pickup device 10B includes a pixel array unit 11, a vertical drive unit 12, a signal processing unit 16, a column readout circuit unit 13, a column signal processing unit 14, a horizontal drive unit 15, and a system control unit. 17 is provided in two systems (A and B), and the signal of each pixel 20 of the pixel array unit 11 is read out from both sides in the pixel row direction.

That is, in the image pickup apparatus 10B, the column reading circuit unit 13A of the system A, the column signal processing unit 14A, the horizontal drive unit 15A, and the system control unit 17A are arranged on one side in the pixel row direction (for example, with respect to the pixel array unit 11). , The column reading circuit unit 13B of the B system, the column signal processing unit 14B, the horizontal drive unit 15B, and the system control unit 17B are arranged on the lower side of the figure (for example, the upper side of the figure). ) Is placed.

The operation of each circuit unit in the two-sided readout type image pickup apparatus 10B is basically the same as the operation of each circuit unit in the one-sided readout type image pickup apparatus 10A. The signal processing unit 16 performs a process of rearranging the pixel signals read by the A system and the B system into a signal arrangement corresponding to the arrangement of the pixels 20 of the pixel array unit 11.

[Semiconductor chip structure]
As the semiconductor chip structure of the one-sided readout type image pickup device 10A or the two-sided readout type image pickup device 10B having the above configuration, a flat semiconductor chip structure and a laminated semiconductor chip structure can be exemplified. The flat-mounted semiconductor chip structure is a structure in which a peripheral circuit portion of the pixel array portion 11 is formed on the same semiconductor substrate as the pixel array portion 11 in which the pixels 20 are arranged in a matrix. The laminated semiconductor chip structure is a structure in which at least two semiconductor substrates are laminated, a pixel array portion 11 is formed on one semiconductor substrate, and a peripheral circuit portion or a part thereof is formed on another semiconductor substrate. .. Further, regarding the pixel structure, when the substrate surface on the side where the wiring layer is formed is the front surface (front surface), a back surface irradiation type pixel structure that takes in the light emitted from the back surface side on the opposite side can also be used. However, a surface-illuminated pixel structure that captures the light emitted from the surface side can also be used.

[Differential amplification type imaging device]
Next, a differential amplification type imaging device applicable to both the one-sided readout method and the two-sided readout method described above will be described. The differential amplification type image pickup device is a type of image pickup device in which the photoelectrically converted signal charge is read out by using a differential amplifier circuit. In the differential amplifier type imaging device, a differential amplifier circuit is configured by using read pixels (selected pixels) in which signals are read and reference pixels in which signals are not read, and the differential amplifier circuit is used. The signal of the read pixel is read out by using it as a pixel read circuit.

In the case of a differential amplification type imaging device, a plurality of pixels arranged two-dimensionally in a matrix in the pixel array unit 11 are composed of a read pixel in which a signal is read and a reference pixel in which the signal is not read. .. Then, in the differential amplifier type image pickup device, a differential amplifier circuit is configured by using the read pixel and the reference pixel, and the differential amplifier circuit is used as the pixel read circuit to read the signal of the read pixel. It will be.

In the pixel array unit 11, the reference pixel forming the differential amplifier circuit together with the read pixel may be fixedly arranged in a specific region of the pixel array unit 11, so-called fixed reference pixel, or selective scanning. It is also possible to perform so-called reference pixel tracking, in which the reading pixel moves following the read pixel that moves in accordance with the above.

[Configuration example of differential amplifier circuit]
Subsequently, an example of the configuration of the differential amplifier circuit configured by using the amplifier transistor of the read pixel and the amplifier transistor of the reference pixel will be described. A circuit diagram of an example of the configuration of the differential amplifier circuit is shown in FIG. Hereinafter, the read pixel will be referred to as a read pixel 20, and the reference pixel will be referred to as a reference pixel 30.

The differential amplifier circuit 50 has a current mirror circuit 51 and a constant current source 52 as a tail current source, and is provided for each pixel row. The current mirror circuit 51 and the constant current source 52 form a differential amplifier circuit 50 together with the amplifier transistor 24 of the read pixel 20 and the amplifier transistor 34 of the reference pixel 30.

(Circuit configuration example of read pixel)
The reading pixel 20 has, for example, a photodiode 21 as a light receiving element. The read pixel 20 has a circuit configuration including a transfer transistor 22, a reset transistor 23, an amplification transistor 24, and a selection transistor 25 in addition to the photodiode 21.

As the four transistors of the transfer transistor 22, the reset transistor 23, the amplification transistor 24, and the selection transistor 25, for example, an N-channel MOS field effect transistor (FET) is used. However, the combination of the conductive types of the four transistors 22 to 25 illustrated here is only an example, and is not limited to these combinations.

In the photodiode 21, the anode electrode is connected to a low-potential side power supply (for example, ground), and the received light is photoelectrically converted into a light charge (here, a photoelectron) having a charge amount corresponding to the light amount, and the light thereof. Accumulates electric charge. The cathode electrode of the photodiode 21 is electrically connected to the gate electrode of the amplification transistor 24 via the transfer transistor 22.

Here, the region where the gate electrodes of the amplification transistor 24 are electrically connected is the floating diffusion (floating diffusion region / impurity diffusion region) capacitance C _fd . The floating diffusion capacitance C _fd is a charge-voltage conversion unit that converts an electric charge into a voltage.

_{A transfer signal TRG_S in which a high level (for example, V DD} level) is active is given to the gate electrode of the transfer transistor 22 from the vertical drive unit 12 shown in FIG. The transfer transistor 22 becomes conductive in response to the transfer signal TRG_S, is photoelectrically converted by the photodiode 21, and transfers _{the optical charge accumulated in the photodiode 21 to the floating diffusion capacitance C fd.}

The reset transistor 23 is connected between the signal line VRD_S connected to the signal line VSL_S from which the pixel signal is output and the floating diffusion capacitance C _fd . A reset signal RST_S that activates a high level is given to the gate electrode of the reset transistor 23 from the vertical drive unit 12. The reset transistor 23 resets the floating diffusion capacitance C _fd by becoming conductive in response to the reset signal RST_S.

Amplifying transistor 24, a gate electrode is connected to the floating diffusion capacitance C _fd, it amplifies the voltage of the floating diffusion capacitance C _fd, and outputs a current corresponding to the voltage as a signal current. The output voltage of the read pixel 20 is generated by this signal current, and is output as a pixel signal to the signal line VSL_S via the selection transistor 25.

The selection transistor 25 is connected between the signal line VSL_S from which the pixel signal is output and the amplification transistor 24. A selection signal SEL_S that activates a high level is given to the gate electrode of the selection transistor 25 from the vertical drive unit 12. The selection transistor 25 opens and closes the path between the signal line VSL_S and the amplification transistor 24 according to the selection signal SEL_S given from the vertical drive unit 12.

A feedback capacitance C _FB is connected between the common connection node of the amplification transistor 24 and the selection transistor 25 and the floating diffusion capacitance C _fd.

(Circuit configuration example of reference pixel)
The reference pixel 30 has a circuit configuration having a photodiode 31, a transfer transistor 32, a reset transistor 33, an amplification transistor 34, a selection transistor 35, a floating diffusion C _fd , and a feedback capacitance C _FB. The configuration of each of these elements (31 to 35, C _fd , C _FB ) is basically the same as that of each element (21 to 26, C _fd , C _FB ) of the read pixel 20.

However, the source electrode of the amplification transistor 34 is connected to the common wiring VCOM together with the source electrode of the amplification transistor 24. Further, the reset transistor 33 is _{connected between the signal line VRD_R to which the reset voltage V rst} is applied and the floating diffusion 36, and the selection transistor 25 is connected between the signal line VSL_R and the amplification transistor 34.

The gate electrode of the transfer transistor 22 has a transfer signal TRG_R that activates a high level, the gate electrode of the reset transistor 33 has a reset signal RST_R that activates a high level, and the gate electrode of the selection transistor 25 has a high reset signal RST_R. The selection signal SEL_R at which the level becomes active is given from the vertical drive unit 12 shown in FIG. 1, respectively.

(Example of current mirror circuit configuration)
The current mirror circuit 51 is composed of, for example, two P-channel MOS type field effect transistors (hereinafter, referred to as “MPPO transistors”), that is, a MOSFET transistor 511 and a MOSFET transistor 512, and each of the NMOS transistor 511 and the NMOS transistor 512. The gate electrodes are connected in common. The MIMO transistor 511 has a diode connection configuration in which a gate electrode and a drain electrode are commonly connected. In the epitaxial transistor 511, the drain electrode is _{connected to the node of the power supply voltage V DD} , and the source electrode is connected to the signal line VSL_R. In the epitaxial transistor 512, the drain electrode is _{connected to the node of the power supply voltage V DD} , and the source electrode is connected to the signal line VSL_S.

The current mirror circuit 51 having the above configuration outputs a reference current from the epitaxial transistor 511 to the signal line VSL_R on the reference pixel 30 side, and outputs a signal current corresponding to the reference current, that is, a signal current equal to the reference current. The signal line VSL_S on the read pixel 20 side is output from. Here, "equal" means not only the case of exactly equality but also the case of substantially equality, and the existence of various variations occurring in design or manufacturing is allowed.

The signal line VSL_S and signal line VRD_S on the read pixel 20 side, the signal line VSL_R and signal line VRD_R on the reference pixel 30 side, and the common wiring VCOM are a group of vertical signal lines 112, and are provided for each pixel row.

The constant current source 52 is connected between a common wiring VCOM that commonly connects the source electrodes of the amplification transistor 24 of the read pixel 20 and the amplification transistor 34 of the reference pixel 30 and a reference potential node (for example, ground). The current from the common wiring VCOM is controlled to be constant. The constant current source 52 can be realized, for example, by an N-channel MOS transistor in which a predetermined bias voltage is applied to the gate electrode (so-called load MOS).

Difference in amplifying a pair of differential input voltages by the current mirror circuit 51 having the above configuration, the amplifier transistor 24 of the read pixel 20, the amplifier transistor 34 of the reference pixel 30, and the constant current source 52 connected to the common wiring VCOM. The dynamic amplifier circuit 50 is configured. The read pixel 20, the reference pixel 30, the current mirror circuit 51, and the constant current source 52 constituting the differential amplifier circuit 50 are provided for each pixel row together with the digital-to-analog converter (ADC), and is shown in FIG. The column reading circuit unit 13 will be configured.

In the differential amplifier circuit 50, one of the pair of differential input voltages is input to the gate electrode of the amplification transistor 24 on the read pixel 20 side, and the other is input to the gate electrode of the amplification transistor 34 on the reference pixel 30 side. Then, the output voltage obtained by amplifying the differential input voltage is output to the column signal processing unit 14 of FIG. 1 via the signal line VSL_S on the drain electrode side of the amplification transistor 24.

By using the differential amplifier circuit 50 having the above configuration as a pixel readout circuit for reading a pixel signal, the amplification factor is larger than when a circuit other than the differential amplifier circuit, for example, a source follower circuit, is used as the pixel readout circuit. Therefore, there is an advantage that the signal can be read out with high conversion efficiency.

[Variation of signal line amplitude range]
Here, the variation in the amplitude range of the signal line VSL when the differential amplifier circuit 50 having the above configuration is mounted on the one-sided readout type image pickup apparatus 10A shown in FIG. 1 will be considered.

The pixels 20 in the one-sided readout type image pickup device 10A equipped with the differential amplifier circuit 50, the constant current source 52 constituting the column readout circuit unit 13, the current mirror circuit 51, and the ADC (analog-to-digital converter) 53. The arrangement relationship of the above is shown in FIG.

Here, as an example, the reference pixel 30 is a pixel adjacent to the read pixel 20 as a reference pixel follower that moves following the read pixel 20 that moves with the selective scanning. This point will be the same in each of the examples described later.

In the one-sided readout type image pickup apparatus 10A, the column readout circuit unit 13 including the pixel 20, the current mirror circuit 51, and the constant current source 52 which is the load MOS is located on one side (one side) of the pixel array unit 11 in the column direction. It will be placed. In this way, when the current mirror circuit 51 and the constant current source 52 are arranged on the same side with respect to the pixel array unit 11, the near-end portion close to the current mirror circuit 51 and the constant current source 52 in terms of distance. The distance of the current path flowing through the vertical wiring such as the vertical signal line VSL, which is wired along the column direction in the pixel array unit 11, is significantly different between the pixel and the far-end pixel.

If the distance of the current path flowing through the vertical wiring is significantly different, the amplitude range of the vertical signal line VSL differs greatly between the near-end pixel and the far-end pixel due to the voltage drop of the wiring resistance of the vertical wiring, so that the dynamic range is compressed. And shading in the pixel array unit 11.

FIG. 5 shows a voltage budget of the near-end pixel and a voltage budget of the far-end pixel in the one-sided readout type image pickup apparatus 10A. In FIG. 5, the MIMO V _ds is the drain-source voltage of the epitaxial transistor constituting the current mirror circuit 51, and the LM V _ds is the drain-source voltage of the NMOS transistor constituting the constant current source 52.

As shown in FIG. 5, the distance of the current path flowing through the vertical wiring is significantly different, so that the near-end pixel and the far-end pixel may be described as a vertical signal line VSL (hereinafter, "VSL wiring"). ), And the voltage drop of the wiring resistance of the wiring connecting the pixel 20/30 and the constant current source 52 (hereinafter, may be referred to as “VPX wiring”) are different. As a result, the amplitude range of the vertical signal line VSL is significantly different between the near-end pixel and the far-end pixel.

[About magnetic field noise]
By the way, when a current flows through a circuit, a magnetic field is generated according to Biot-Savart's law, which becomes noise and adversely affects the circuit. Then, as shown in FIG. 6, when the electric current reciprocates along the same path, the generated magnetic fields strengthen each other, so that stronger noise is generated. There is a concern that this magnetic field noise interferes with a highly sensitive circuit and is observed as fixed pattern noise.

In the case of the differential amplification type imaging device, the random noise component generated by the amplification transistor 34 (see FIG. 3) of the reference pixel 30 can be suppressed by differential reading. However, by suppressing the random noise component, the magnetic field noise, which has not been a problem in the differential amplification type imaging device, becomes relatively worse.

<Embodiment of the present disclosure>
The image pickup apparatus according to the embodiment of the present disclosure is a differential amplification type image pickup apparatus, and employs a double-sided readout method for reading pixel signals from both sides in the pixel row direction. Further, the image pickup apparatus according to the embodiment of the present disclosure is a current mirror circuit 51 that constitutes a differential amplifier circuit together with the amplification transistor of the read pixel 20 and the amplification transistor of the reference pixel 30 in the differential amplification type imaging device of the double-sided readout system. And the constant current source 52 are arranged to face each other on both sides in the row direction with the pixel array portion 11 interposed therebetween.

When arranging the current mirror circuit 51 and the constant current source 52 face-to-face with the pixel array unit 11 sandwiched between them, the current mirror circuit 51 and the constant current source 52 face each other with the pixel array unit 11 as a unit, for example, a plurality of pixel trains as a unit. It can be configured to be arranged. More specifically, the current mirror circuit 51 and the constant current source 52 are arranged face-to-face with the pixel array unit 11 interposed therebetween, for example, for each pixel array or for each of a plurality of pixel sequences. Can be done.

By arranging the current mirror circuit 51 and the constant current source 52 facing each other with the pixel array unit 11 interposed therebetween, the wiring resistance of the VSL wiring and the wiring of the VPX wiring between the pixels 20/30 and the constant current source 52. Since the voltage drop due to the resistance is constant, it is possible to suppress variations in the amplitude range of the vertical signal line VSL between the near-end pixel and the far-end pixel. Here, "constant" means not only a strictly constant case but also a substantially constant case, and the existence of various variations occurring in design or manufacturing is allowed.

Further, by arranging the current mirror circuit 51 and the constant current source 52 facing each other with the pixel array unit 11 interposed therebetween, the current paths of the reference current flowing through the reference pixel 30 and the signal current flowing through the read pixel 20 are in the column direction. It becomes one direction. Therefore, it is possible to reduce the magnetic field noise generated by the current flowing through the circuit as compared with the one-sided readout type differential amplification type imaging device. The details will be described later.

By the way, in the differential type amplification / reading by the differential amplifier circuit, the signal can be read out with higher conversion efficiency than in the case of using a circuit other than the differential amplifier circuit, for example, a source follower circuit. However, for example, in bright light when high-intensity light is incident, it is desirable that reading by a source follower (SF) circuit having a wide dynamic range is performed instead of reading by a differential amplifier circuit.

Therefore, the image pickup apparatus according to the embodiment of the present disclosure has a wide dynamic range and a differential type amplification / reading mode (hereinafter, may be referred to as “differential mode”) by a differential amplifier circuit having high conversion efficiency. It has a read mode by a source follower circuit (hereinafter, may be referred to as "SF mode"), and has a configuration in which both modes can be switched. Then, by appropriately switching between the differential mode and the SF mode, more appropriate reading processing can be performed.

Hereinafter, a specific embodiment of the double-sided readout type differential amplification type image pickup apparatus according to the present embodiment in which the current mirror circuit 51 and the constant current source 52 are arranged facing each other with the pixel array unit 11 interposed therebetween will be described. ..

[Example 1]
The first embodiment is an example in which the current mirror circuit 51 and the constant current source 52 are arranged facing each other with the pixel array unit 11 in units of two pixel sequences adjacent to each other.

FIG. 7 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the first embodiment, and a current path in the differential mode. FIG. 8 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the first embodiment, and a current path in the SF mode. As a matter of course, in the SF mode, there is no reference pixel 30, and all are read pixels 20.

As shown in FIGS. 7 and 8, the differential amplification type imaging device according to the first embodiment transmits pixel signals on both sides of the pixel array unit 11 in which the read pixels 20 and the reference pixels 30 are arranged in the pixel row direction. The column reading circuit unit 13 for reading is arranged. Then, in the differential amplification type imaging device according to the first embodiment, the current mirror circuit 51 and the constant current source 52 constituting the column readout circuit unit 13 have pixels in units of two pixel sequences adjacent to each other. It is configured to be arranged facing each other on both sides in the row direction with the array portion 11 interposed therebetween.

In the differential amplification type imaging device according to the first embodiment, in the differential mode, the upper current mirror circuit 51 and the lower constant current source 52 are ... It functions as a column reading circuit unit 13 for each of the pixel rows of, i row, i + 2 row, i + 4 row, .... Further, as shown by the thick dotted line in FIG. 7, the lower current mirror circuit 51 and the upper constant current source 52 are ..., i + 1 row, i + 3 row, i + 5 row, ... It functions as a column reading circuit unit 13 for a pixel string.

In the SF mode, as shown by the thin solid line in FIG. 8, the upper constant current source 52 and the ADC 53 are the column reading circuit unit 13 of the pixel 20 corresponding to the reading pixel (20) in the differential mode. Functions as. Further, as shown by the broken line of the thin line in FIG. 8, the lower constant current source 52 and the ADC 53 serve as the column readout circuit unit 13 of the pixel 20 corresponding to the reference pixel (30) in the differential mode. Function.

FIG. 9 shows an example of the circuit configuration in the differential mode of the differential amplification type imaging device according to the first embodiment, and FIG. 10 shows an example of the circuit configuration in the SF mode of the differential amplification type imaging device according to the first embodiment. Shown in. In FIGS. 9 and 10, for the sake of simplification of the drawings, a pixel array of a total of 4 pixels of 2 pixel rows adjacent to each other in each pixel column of the i column and the i + 1 column is shown. Then, in the circuit configuration in the differential mode shown in FIG. 9, the two pixels in the upper pixel row are the read pixels 20, and the two pixels in the lower pixel row are the reference pixels 30.

Switching between the differential mode and the SF mode, that is, switching between the circuit configuration in the differential mode shown in FIG. 9 and the circuit configuration in the SF mode shown in FIG. It is realized by switching. For example, in bright light when high-intensity light is incident, the SF mode, which is a read mode by a source follower circuit with a wide dynamic range, is selected, and in other than bright light, differential amplification is performed by a differential amplifier circuit with high conversion efficiency. The differential mode, which is the read mode, can be selected. In this way, by appropriately switching between the differential mode and the SF mode, more appropriate reading processing can be performed.

Then, in the differential mode shown in FIG. 9, for example, the upper current mirror circuit 51 responds to the reference current output from the reference pixel 30 to the current path shown by the thick dotted line in FIG. 9 in the pixel row of row i. The signal current is supplied to the read pixel 20 through the current path shown by the solid line shown by the thick line in FIG. As shown by the thick dotted line and the thick solid line in FIG. 9, the current paths of the reference current flowing through the reference pixel 30 and the signal current flowing through the reading pixel 20 are unidirectional in the column direction. In FIG. 10 showing the circuit configuration in the SF mode, the current paths of the two pixels 20 in the upper pixel row are shown by thick solid lines, and the current paths of the two pixel 20s in the lower pixel row are shown by thick dotted lines. It is shown by.

As described above, the differential amplification type imaging device according to the first embodiment has a double-sided readout system, and the current mirror circuit 51 and the constant current source 52 constituting the column readout circuit unit 13 are adjacent to each other. The two pixel trains are used as a unit and are arranged facing each other with the pixel array unit 11 interposed therebetween. With this configuration, the following actions and effects can be obtained.

By arranging the current mirror circuit 51 and the constant current source 52 facing each other with the pixel array unit 11 interposed therebetween, the wiring resistance of the VSL wiring (vertical signal line VSL) and the pixels 20/30 and the constant current source 52 are provided. Since the voltage drop due to the wiring resistance of the connected VPX wiring becomes constant, it is possible to suppress the variation in the amplitude range of the VSL wiring between the near-end pixel and the far-end pixel. Here, "constant" means not only a strictly constant case but also a substantially constant case, and the existence of various variations occurring in design or manufacturing is allowed.

FIG. 11 shows the current paths of the near-end pixel and the far-end pixel in the differential mode in a simplified manner. As shown in FIG. 11, the wiring length (that is, the current path length) of the VSL wiring + VPX wiring in the differential mode is substantially equal between the near-end pixel and the far-end pixel. As a result, the voltage drop due to the wiring resistance of the VSL wiring and the wiring resistance of the VPX wiring becomes constant, so that the variation in the amplitude range of the VPX wiring between the near-end pixel and the far-end pixel can be suppressed.

FIG. 12 shows the voltage budget of the near-end pixel and the voltage budget of the far-end pixel in the differential mode in the double-sided readout type image pickup apparatus. In FIG. 12, the MIMO V _ds is the drain-source voltage of the epitaxial transistor constituting the current mirror circuit 51, and the LM V _ds is the drain-source voltage of the NMOS transistor constituting the constant current source 52.

Further, in the differential amplification type imaging device according to the first embodiment, the current mirror circuit 51 and the constant current source 52 are arranged face-to-face with the pixel array unit 11 interposed therebetween, so that the reference current flowing through the reference pixel 30 and the reference current flow through the reference pixel 30 are arranged. The current path of the signal current flowing through the read pixel 20 is unidirectional in the column direction. Therefore, it is possible to reduce the magnetic field noise generated by the current flowing through the circuit as compared with the one-sided readout type differential amplification type imaging device.

The operation and effect of the differential amplification type imaging device according to the first embodiment are the same in each of the examples described later.

[Example 2]
The second embodiment is a modification of the first embodiment, in which the arrangement relationship between the current mirror circuit 51 and the constant current source 52 with respect to the pixel array unit 11 is alternately inverted for each pixel sequence.

FIG. 13 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the second embodiment, and a current path in the differential mode. FIG. 14 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the third embodiment, and a current path in the SF mode.

In arranging the current mirror circuit 51 and the constant current source 52 so as to be oriented with the pixel array unit 11 interposed therebetween, in the differential amplification type imaging apparatus according to the first embodiment, the pixel array unit is in units of two adjacent pixel sequences. The constant current source 52 was arranged on the 11 side, and the current mirror circuit 51 was arranged outside the constant current source 52. On the other hand, in the differential amplification type imaging device according to the second embodiment, as shown in FIGS. 13 and 14, the arrangement relationship between the current mirror circuit 51 and the constant current source 52 with respect to the pixel array unit 11 is determined by the pixel sequence. The layout is such that they are alternately inverted each time.

Specifically, for example, in the i-row, the constant current source 52 is arranged on the pixel array portion 11 side, the current mirror circuit 51 is arranged outside the constant current source 52, and in the i + 1 row, the constant current source 52 is arranged on the pixel array portion 11 side. The current mirror circuit 51 is arranged, and the constant current source 52 is arranged outside the current mirror circuit 51. In the i + 2 row, the constant current source 52 is arranged on the pixel array unit 11 side, the current mirror circuit 51 is arranged outside the constant current source 52, and in the i + 3 row, the current mirror circuit 51 is arranged on the pixel array unit 11 side. , The constant current source 52 is arranged outside the current mirror circuit 51. In this way, the differential amplification type imaging device according to the third embodiment has a configuration in which the arrangement relationship between the Karen-0090 tomiller circuit 51 and the constant current source 52 is alternately inverted for each pixel sequence.

As described above, according to the differential amplification type imaging device according to the second embodiment, the arrangement relationship between the current mirror circuit 51 and the constant current source 52 with respect to the pixel array unit 11 is alternately inverted for each pixel sequence. With the configuration, the symmetry of the layout can be maintained, and the manufacturing variation can be suppressed.

[Example 3]
The third embodiment is an example in which the current mirror circuit 51 and the constant current source 52 are arranged facing each other with the pixel array unit 11 in units of four pixel sequences adjacent to each other.

FIG. 15 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the third embodiment, and a current path in the differential mode. FIG. 16 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the third embodiment, and a current path in the SF mode.

As shown in FIGS. 15 and 16, in the differential amplification type imaging device according to the third embodiment, the current mirror circuit 51 and the constant current source 52 constituting the column readout circuit unit 13 are included in the double-sided readout type imaging device. , The configuration is such that four pixel rows adjacent to each other are arranged face-to-face on both sides in the row direction with the pixel array portion 11 as a unit.

In the differential amplification type imaging device according to the third embodiment, in the differential mode, as shown by the solid line in FIG. 15, the upper current mirror circuit 51 straddling the i-row and the i + 1-row, and the i + 1-row The constant current sources 52 and 52 on the lower side of the i + 2 row function as the column reading circuit unit 13 of each pixel row of the ..., i + 1 row, i + 3 row, .... Further, as shown by a broken line in FIG. 15, the lower current mirror circuit 51 straddling the i + 1 row and the i + 3 row, and the upper constant current sources 52 and 52 of the i + 1 row and the i + 2 row ... It functions as a column reading circuit unit 13 for each of the pixel rows of, i row, i + 2 row, i + 4 row, ....

In the SF mode, as shown by the solid line in FIG. 16, the upper constant current source 52 and the ADC 53 function as the column reading circuit unit 13 of the pixel 20 corresponding to the reading pixel (20) in the differential mode. do. Further, as shown by the broken line in FIG. 16, the lower constant current source 52 and the ADC 53 function as the column readout circuit unit 13 of the pixel 20 corresponding to the reference pixel (30) in the differential mode. ..

[Example 4]
The fourth embodiment is a modification of the first embodiment, and is an example having a horizontal connection wiring and a horizontal connection switch for electrically connecting (so-called horizontal connection) the reference pixel 30 side between the pixel rows. The horizontal connection wiring and the horizontal connection switch that horizontally connect the reference pixel 30 side between the pixel rows are for reducing noise on the reference pixel 30 side.

FIG. 17 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the fourth embodiment, and a current path in the differential mode. In the differential amplification type imaging device according to the fourth embodiment, in the column readout circuit unit 13, the first horizontal connection wiring VSLRCNT and the second horizontal connection wiring LMCTT sandwich the constant current source 52 in the pixel row direction. Is provided.

The first horizontal connection wiring VSLRCNT provided in the column readout circuit unit 13 on the upper side of the pixel array unit 11 is connected to each constant current source 52 of ..., i row, i + 2 row, i + 4 row, ... The first horizontal connection wiring VSLRCNT provided in the column readout circuit unit 13 on the lower side of the pixel array unit 11 is connected to each constant current source 52 of ..., i + 1 row, i + 3 row, i + 5 row, ... It is connected.

_{The first horizontal connection switch SW 1} is between the wiring between the selection transistor 35 of the reference pixel 30 and the current mirror circuit 51 (corresponding to the signal line VSL_R in FIG. 3) and the first horizontal connection wiring VSLRCNT. Is connected. Further, the wiring between each source electrode of the amplification transistor 24 of the reading pixel 20 and the amplification transistor 34 of the reference pixel 30 and the constant current source 52 (corresponding to the common wiring VCOM in FIG. 3) and the second horizontal connection wiring LMCTT. A second horizontal connection switch SW ₂ is connected to and from.

FIG. 18 shows the first horizontal connection wiring VSLRCNT, the second horizontal connection wiring LMCTT, the first horizontal connection switch SW ₁ , and the second horizontal connection switch SW in the differential amplification type imaging apparatus according to the fourth embodiment. shows the specific connection relationships _2. Both the first horizontal connection switch SW ₁ and the second horizontal connection switch SW ₂ are in the on (closed) state in the differential mode.

As described above, the differential amplification type imaging device according to the fourth embodiment is the first horizontal connection wiring VSLRCNT and the differential amplification type imaging device according to the first embodiment for the purpose of reducing noise on the reference pixel 30 side. The second horizontal connection wiring LMCNT, the first horizontal connection switch SW ₁ and the second horizontal connection switch SW ₂ are provided in the column reading circuit unit 13.

Then, in the differential mode, the reference pixel 30 side is affected by the actions of the first horizontal connection wiring VSLRCNT, the second horizontal connection wiring LMCNT, and the first horizontal connection switch SW ₁ and the second horizontal connection switch SW _2. The noise on the reference pixel 30 side is averaged through the first horizontal connection wiring VSLRCNT and the second horizontal connection wiring LMCNT by horizontally connecting the two pixels to each other, so that the noise on the reference pixel 30 side can be reduced. Can be done.

[Example 5]
The fifth embodiment is a modification of the fourth embodiment, and is an example in which the column reading circuit unit 13 on the lower side and the upper side (so-called north-south) realizes horizontal connection for each pixel sequence.

FIG. 19 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the fifth embodiment, and a current path in the differential mode. As shown in FIG. 19, in the differential amplification type imaging device according to the fifth embodiment, the read pixels 20 and the read pixels 20 and each pixel row are electrically connected (horizontally connected) by the north-south column reading circuit unit 13. The VPX wiring connecting the reference pixel 30 and the constant current source 52 and the VSL wiring on the reference pixel 30 side are extended to extend to the north-south column readout circuit unit 13. Then, the first horizontal connection switch SW ₁ and the second horizontal connection switch SW ₂ are arranged for each pixel row, and the reference pixel 30 side is electrically connected between the pixel rows in the north-south column readout circuit unit 13. It is composed.

[Example 6]
The sixth embodiment is a modification of the fifth embodiment, and is an example in which each VPX wiring of two adjacent pixel rows is combined into one.

FIG. 20 is a block diagram showing an arrangement example of the current mirror circuit 51 and the constant current source 52 in the differential amplification type imaging device according to the sixth embodiment, and a current path in the differential mode. As shown in FIG. 20, in the differential amplification type imaging device according to the sixth embodiment, the wiring VPX connecting the pixels 20 (30) and the constant current source 52 is combined into one between two adjacent pixel rows. It is composed.

FIG. 21 shows the connection relationship between the horizontal connection wiring and the horizontal connection switch in the differential mode of the differential amplification type imaging device according to the sixth embodiment, and the horizontal connection wiring and the horizontal connection in the differential amplification type imaging device according to the sixth embodiment. FIG. 22 shows the connection relationship of the connection switch in the SF mode. In FIGS. 21 and 22, for the sake of simplification of the drawings, a pixel array of a total of 4 pixels, which is two rows of pixels adjacent to each other in two rows of pixels adjacent to each other, is shown. Then, in the circuit configuration in the differential mode shown in FIG. 21, the two pixels in the upper pixel row are the read pixels 20, and the two pixels in the lower pixel row are the reference pixels 30.

In FIG. 21, which shows the circuit configuration in the differential mode, the current path of the read pixel 20 is shown by a thick solid line, and the current path of the reference pixel 30 is shown by a thick dotted line. Further, in FIG. 22 showing the circuit configuration in the SF mode, the current paths of the two pixels 20 in the upper pixel row are shown by thick solid lines, and the current paths of the two pixel 20s in the lower pixel row are shown by thick dotted lines. It is shown by.

According to the differential amplification type imaging apparatus according to the sixth embodiment, the wiring VPX connecting the pixels 20 (30) and the constant current source 52 is integrated into one wire between two adjacent pixel rows, so that the second is The number of horizontal connection switches SW ₂ can be reduced to half that of the fifth embodiment. Thereby, the switch area and the wiring area can be reduced as compared with the case of the fifth embodiment.

<Modification example>
The technique according to the present disclosure has been described above based on the preferred embodiment, but the technique according to the present disclosure is not limited to the embodiment. The configuration and structure of the imaging device described in the above embodiment are examples, and can be changed as appropriate.

For example, in the above embodiment, a differential amplifier / read mode (differential mode) by a differential amplifier circuit and a read mode (SF mode) by a source follower circuit are provided, and both modes can be switched. Although the above image pickup device has been described as an example, the technique of the present disclosure can be applied to an image pickup device having only a differential amplification / readout mode.

Further, in the above embodiment, the reference pixel 30 has been described by taking as an example a case where the reference pixel 30 is applied to an image pickup device for following a reference pixel that moves following a read pixel 20 that moves with selective scanning. The technique of the present disclosure can also be applied to a so-called fixed reference pixel imaging device in which the reference pixel 30 is fixedly arranged in a specific region of the unit 11.

<Application example>
The imaging device according to the present embodiment described above can be used for various devices that sense light such as visible light, infrared light, ultraviolet light, and X-ray, as shown in FIG. 23, for example. Specific examples of various devices are listed below.

・ Devices that take images for viewing, such as digital cameras and portable devices with camera functions. ・ For safe driving such as automatic stop and recognition of the driver's condition, in front of the car Devices used for traffic, such as in-vehicle sensors that photograph the rear, surroundings, and interior of vehicles, surveillance cameras that monitor traveling vehicles and roads, and distance measurement sensors that measure distance between vehicles, etc. Equipment used in home appliances such as TVs, refrigerators, and air conditioners to take pictures and operate the equipment according to the gestures ・ Endoscopes, devices that perform angiography by receiving infrared light, etc. Equipment used for medical and healthcare ・ Equipment used for security such as surveillance cameras for crime prevention and cameras for person authentication ・ Skin measuring instruments for taking pictures of the skin and taking pictures of the scalp Equipment used for beauty such as microscopes ・ Equipment used for sports such as action cameras and wearable cameras for sports applications ・ Cameras for monitoring the condition of fields and crops, etc. Equipment used for agriculture

<Application example of the technology according to the present disclosure>
The technology according to the present disclosure can be applied to various products. A more specific application example will be described below.

[Electronic device of the present disclosure]
Here, a case where it is applied to an imaging system such as a digital still camera or a video camera, a mobile terminal device having an imaging function such as a mobile phone, or an electronic device such as a copier using an imaging device for an image reading unit will be described.

(Example of imaging system)
FIG. 24 is a block diagram showing a configuration example of an imaging system which is an example of the electronic device of the present disclosure.

As shown in FIG. 24, the image pickup system 100 according to this example includes an image pickup optical system 101 including a lens group and the like, an image pickup unit 102, a DSP (Digital Signal Processor) circuit 103, a frame memory 104, a display device 105, and a recording device 106. , Operation system 107, power supply system 108, and the like. The DSP circuit 103, the frame memory 104, the display device 105, the recording device 106, the operation system 107, and the power supply system 108 are connected to each other via the bus line 109.

The imaging optical system 101 captures incident light (image light) from the subject and forms an image on the imaging surface of the imaging unit 102. The imaging unit 102 converts the amount of incident light imaged on the imaging surface by the optical system 101 into an electric signal in pixel units and outputs it as a pixel signal. The DSP circuit 103 performs general camera signal processing, for example, white balance processing, demosaic processing, gamma correction processing, and the like.

The frame memory 104 is appropriately used for storing data in the process of signal processing in the DSP circuit 103. The display device 105 includes a panel-type display device such as a liquid crystal display device or an organic EL (electroluminescence) display device, and displays a moving image or a still image captured by the imaging unit 102. The recording device 106 records the moving image or still image captured by the imaging unit 102 on a portable semiconductor memory, an optical disk, a recording medium such as an HDD (Hard Disk Drive), or the like.

The operation system 107 issues operation commands for various functions of the image pickup apparatus 100 under the operation of the user. The power supply system 108 appropriately supplies various power supplies that serve as operating power supplies for the DSP circuit 103, the frame memory 104, the display device 105, the recording device 106, and the operation system 107 to these supply targets.

In the image pickup system 100 having the above configuration, the image pickup apparatus according to the above-described embodiment can be used as the image pickup unit 102. According to the imaging device, the occurrence of streaking can be suppressed, so that a high-quality captured image without noise such as streaking can be obtained.

[Application example to mobile]
The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure includes any type of movement such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility, airplanes, drones, ships, robots, construction machines, agricultural machines (tractors), and the like. It may be realized as an image pickup device mounted on the body.

FIG. 25 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technique according to the present disclosure can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via the communication network 12001. In the example shown in FIG. 25, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside information detection unit 12030, an in-vehicle information detection unit 12040, and an integrated control unit 12050. Further, as a functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are shown.

The drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 provides a driving force generator for generating the driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism for adjusting and a braking device for generating a braking force of a vehicle.

The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, blinkers or fog lamps. In this case, the body system control unit 12020 may be input with radio waves transmitted from a portable device that substitutes for the key or signals of various switches. The body system control unit 12020 receives inputs of these radio waves or signals and controls a vehicle door lock device, a power window device, a lamp, and the like.

The vehicle exterior information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, the image pickup unit 12031 is connected to the vehicle exterior information detection unit 12030. The vehicle outside information detection unit 12030 causes the image pickup unit 12031 to capture an image of the outside of the vehicle and receives the captured image. The vehicle exterior information detection unit 12030 may perform object detection processing or distance detection processing such as a person, a vehicle, an obstacle, a sign, or a character on the road surface based on the received image.

The imaging unit 12031 is an optical sensor that receives light and outputs an electric signal according to the amount of the light received. The image pickup unit 12031 can output an electric signal as an image or can output it as distance measurement information. Further, the light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

The vehicle interior information detection unit 12040 detects information in the vehicle. For example, a driver state detection unit 12041 that detects the driver's state is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether the driver is dozing.

The microcomputer 12051 calculates the control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit. A control command can be output to 12010. For example, the microcomputer 12051 realizes ADAS (Advanced Driver Assistance System) functions including vehicle collision avoidance or impact mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, and the like. It is possible to perform cooperative control for the purpose of.

Further, the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform coordinated control for the purpose of automatic driving, etc., which runs autonomously without depending on the operation.

Further, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the vehicle exterior information detection unit 12030. For example, the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the external information detection unit 12030, and performs coordinated control for the purpose of anti-glare such as switching the high beam to the low beam. It can be carried out.

The audio-image output unit 12052 transmits an output signal of at least one of audio and an image to an output device capable of visually or audibly notifying the passenger of the vehicle or the outside of the vehicle. In the example of FIG. 25, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an onboard display and a heads-up display.

FIG. 26 is a diagram showing an example of the installation position of the imaging unit 12031.

In FIG. 26, the vehicle 12100 has image pickup units 12101, 12102, 12103, 12104, 12105 as the image pickup unit 12031.

The imaging units 12101, 12102, 12103, 12104, 12105 are provided at positions such as, for example, the front nose, side mirrors, rear bumpers, back doors, and the upper part of the windshield in the vehicle interior of the vehicle 12100. The image pickup unit 12101 provided on the front nose and the image pickup section 12105 provided on the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100. The imaging units 12102 and 12103 provided in the side mirrors mainly acquire images of the side of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or the back door mainly acquires an image of the rear of the vehicle 12100. The images in front acquired by the imaging units 12101 and 12105 are mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

Note that FIG. 26 shows an example of the photographing range of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and the imaging range 12114 indicates the imaging range of the imaging units 12102 and 12103. The imaging range of the imaging unit 12104 provided on the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 as viewed from above can be obtained.

At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image pickup units 12101 to 12104 may be a stereo camera composed of a plurality of image pickup elements, or may be an image pickup element having pixels for phase difference detection.

For example, the microcomputer 12051 has a distance to each three-dimensional object within the imaging range 12111 to 12114 based on the distance information obtained from the imaging units 12101 to 12104, and a temporal change of this distance (relative velocity with respect to the vehicle 12100). By obtaining can. Further, the microcomputer 12051 can set an inter-vehicle distance to be secured in front of the preceding vehicle in advance, and can perform automatic brake control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. In this way, it is possible to perform coordinated control for the purpose of automatic driving or the like in which the vehicle travels autonomously without depending on the operation of the driver.

For example, the microcomputer 12051 converts three-dimensional object data related to a three-dimensional object into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, electric poles, and other three-dimensional objects based on the distance information obtained from the imaging units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that can be seen by the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microphone 12061 or the display unit 12062 is used. By outputting an alarm to the driver and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving support for collision avoidance can be provided.

At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured image of the imaging units 12101 to 12104. Such pedestrian recognition includes, for example, a procedure for extracting feature points in an image captured by an imaging unit 12101 to 12104 as an infrared camera, and pattern matching processing for a series of feature points indicating the outline of an object to determine whether or not the pedestrian is a pedestrian. It is done by the procedure to determine. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 outputs a square contour line for emphasizing the recognized pedestrian. The display unit 12062 is controlled so as to superimpose and display. Further, the audio image output unit 12052 may control the display unit 12062 so as to display an icon or the like indicating a pedestrian at a desired position.

The example of the vehicle control system to which the technique according to the present disclosure can be applied has been described above. The technique according to the present disclosure can be applied to, for example, the imaging unit 12031 among the configurations described above. Then, by applying the technique according to the present disclosure to the imaging unit 12031 or the like, magnetic field noise at the time of differential readout can be suppressed, so that a high-quality captured image with low noise can be obtained.

<Structure that can be taken by this disclosure>
The present disclosure may also have the following configuration.

≪A. Imaging device ≫
[A-1] A pixel array unit in which a read pixel in which a signal is read and a reference pixel in which a signal is not read are arranged.
A constant current source connected to each source electrode of the amplification transistor of the read pixel and the amplification transistor of the reference pixel, and
A current mirror circuit that supplies a signal current corresponding to the reference current output from the reference pixel to the read pixel.
With
The amplifier transistor of the read pixel and the amplifier transistor of the reference pixel form a differential amplifier circuit together with a constant current source and a current mirror circuit.
The current mirror circuit and the constant current source are arranged to face each other on both sides in the pixel array direction with the pixel array portion interposed therebetween for each pixel array.
Imaging device.
[A-2] The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of a plurality of pixel trains.
The imaging device according to the above [A-1].
[A-3] The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of two pixel sequences adjacent to each other.
The imaging device according to the above [A-2].
[A-4] The arrangement relationship between the current mirror circuit and the constant current source with respect to the pixel array unit is alternately inverted for each pixel sequence.
The imaging device according to the above [A-3].
[A-5] The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of four pixel sequences adjacent to each other.
The imaging device according to the above [A-2].
[A-6] It has a horizontal connection wiring and a horizontal connection switch that electrically connect the reference pixel side between pixel rows.
The imaging device according to any one of the above [A-1] to the above [A-5].
[A-7] Column readout circuit units are provided on both sides in the pixel row direction with the pixel array unit in between.
Wiring and vertical signal lines connecting the pixels and the constant current source are provided extending to the column readout circuits on both sides.
The horizontal connection wiring and the horizontal connection switch electrically connect the reference pixel side between the pixel rows in the column readout circuits on both sides.
The imaging device according to the above [A-6].
[A-8] One wiring for connecting the pixel and the constant current source is provided together between adjacent pixel rows.
The imaging device according to the above [A-7].
[A-9] It has a differential type amplifier / read mode by a differential amplifier circuit and a read mode by a source follower circuit, and both modes can be switched.
The imaging device according to any one of the above [A-1] to the above [A-8].

≪B. Electronic equipment ≫
[B-1] A pixel array unit in which a read pixel in which a signal is read and a reference pixel in which a signal is not read are arranged.
A constant current source connected to each source electrode of the amplification transistor of the read pixel and the amplification transistor of the reference pixel, and
A current mirror circuit that supplies a signal current corresponding to the reference current output from the reference pixel to the read pixel.
With
The amplifier transistor of the read pixel and the amplifier transistor of the reference pixel form a differential amplifier circuit together with a constant current source and a current mirror circuit.
The current mirror circuit and the constant current source are arranged to face each other on both sides in the pixel array direction with the pixel array portion interposed therebetween for each pixel array.
An electronic device having an imaging device.
[B-2] The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of a plurality of pixel trains.
The electronic device according to the above [B-1].
[B-3] The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of two pixel sequences adjacent to each other.
The electronic device according to the above [B-2].
[B-4] The arrangement relationship between the current mirror circuit and the constant current source with respect to the pixel array unit is alternately inverted for each pixel sequence.
The electronic device according to the above [B-3].
[B-5] The current mirror circuit and the constant current source are arranged facing each other with a pixel array portion in between, in units of four pixel sequences adjacent to each other.
The electronic device according to the above [B-2].
[B-6] It has a horizontal connection wiring and a horizontal connection switch that electrically connect the reference pixel side between pixel rows.
The electronic device according to any one of the above [B-1] to the above [B-5].
[B-7] Column readout circuit units are provided on both sides in the pixel row direction with the pixel array unit in between.
Wiring and vertical signal lines connecting the pixels and the constant current source are provided extending to the column readout circuits on both sides.
The horizontal connection wiring and the horizontal connection switch electrically connect the reference pixel side between the pixel rows in the column readout circuits on both sides.
The electronic device according to the above [B-6].
[B-8] One wiring for connecting the pixel and the constant current source is provided together between adjacent pixel rows.
The electronic device according to the above [B-7].
[B-9] It has a differential type amplifier / read mode by a differential amplifier circuit and a read mode by a source follower circuit, and both modes can be switched.
The electronic device according to any one of the above [B-1] to the above [B-8].

10A ... One-sided readout type imager, 10B ... Double-sided readout type imager, 11 ... Pixel array unit, 12 ... Vertical drive unit, 13 ... Column readout circuit unit, 14 ... -Column signal processing unit, 15 ... horizontal drive unit, 16 ... system control unit, 20 ... selected pixel, 30 ... reference pixel, 50 ... differential amplifier circuit, 51 ... current Mirror circuit, 52 ... constant current source, 53 ... analog-to-digital converter (ADC), VCOM ... common wiring, VSLRCNT ... first horizontal connection wiring, LMCNT ... second horizontal Connection wiring, SW ₁ ... 1st horizontal connection switch, SW ₂ ... 2nd horizontal connection switch

Claims (10)

A pixel array unit in which a read pixel in which a signal is read and a reference pixel in which a signal is not read are arranged.
A constant current source connected to each source electrode of the amplification transistor of the read pixel and the amplification transistor of the reference pixel, and
A current mirror circuit that supplies a signal current corresponding to the reference current output from the reference pixel to the read pixel.
With
The amplifier transistor of the read pixel and the amplifier transistor of the reference pixel form a differential amplifier circuit together with a constant current source and a current mirror circuit.
The current mirror circuit and the constant current source are arranged facing each other on both sides in the pixel row direction with the pixel array portion in between.
Imaging device. The current mirror circuit and the constant current source are arranged face-to-face with a pixel array unit in units of a plurality of pixel trains.
The imaging device according to claim 1. The current mirror circuit and the constant current source are arranged facing each other with the pixel array portion in between, in units of two pixel sequences adjacent to each other.
The imaging device according to claim 2. The arrangement relationship between the current mirror circuit and the constant current source with respect to the pixel array unit is alternately inverted for each pixel sequence.
The imaging device according to claim 3. The current mirror circuit and the constant current source are arranged face-to-face with the pixel array portion in the unit of four pixel sequences adjacent to each other.
The imaging device according to claim 2. It has a horizontal connection wiring and a horizontal connection switch that electrically connect the reference pixel side between pixel rows.
The imaging device according to claim 1. It has column readout circuits on both sides of the pixel array in the pixel row direction.
Wiring and vertical signal lines connecting the pixels and the constant current source are provided extending to the column readout circuits on both sides.
The horizontal connection wiring and the horizontal connection switch electrically connect the reference pixel side between the pixel rows in the column readout circuits on both sides.
The imaging device according to claim 6. One wiring connecting the pixels and the constant current source is provided together between adjacent pixel rows.
The imaging device according to claim 7. It has a differential amplifier / read mode using a differential amplifier circuit and a read mode using a source follower circuit, and both modes can be switched.
The imaging device according to claim 1. A pixel array unit in which a read pixel in which a signal is read and a reference pixel in which a signal is not read are arranged.
A constant current source connected to each source electrode of the amplification transistor of the read pixel and the amplification transistor of the reference pixel, and
A current mirror circuit that supplies a signal current corresponding to the reference current output from the reference pixel to the read pixel.
With
The amplifier transistor of the read pixel and the amplifier transistor of the reference pixel form a differential amplifier circuit together with a constant current source and a current mirror circuit.
The current mirror circuit and the constant current source are arranged facing each other on both sides in the pixel row direction with the pixel array portion in between.
An electronic device having an imaging device.

Images