KR100795692B1 - A light receiver - Google Patents

Abstract

A light receiver is provided to improve noise property by outputting a signal normally in case of a wanted signal and eliminating effectively a disturbance light in case of a disturbance light noise. A light receiver comprises a receiving & amplifying unit(210), an HPF(High Pass Filter,220), a signal processor(230) and a gain controller(240). The receiving & amplifying unit(210) converts a received light signal into a voltage signal and amplifies the voltage signal in response to a gain control signal. The HPF(220) passes only a high frequency component among the voltage signal outputted by the receiving & amplifying unit(210). The signal processor(230) generates a digital data signal by using the voltage signal outputted by the HPF unit(220). The gain controller(240) generates the gain control signal by using the amplified voltage signal outputted by the receiving & amplifying unit(210).

Description

Optical receiver {A light receiver}

1 shows a conventional optical receiver.

2 shows an embodiment of an optical receiving apparatus according to the present invention.

3 illustrates an embodiment of a receiving and amplifying unit of an optical receiving apparatus.

4 illustrates an embodiment of a signal processor of the optical receiver.

5 illustrates an embodiment of a gain control unit of the optical receiver.

6 illustrates an embodiment of a demodulator of the gain control unit.

7 illustrates an embodiment of the charge / discharge control unit of the gain control unit.

8 illustrates an embodiment of an interface unit of the gain control unit.

9 shows the relationship between the gain control signal and the gain of the amplifier according to an embodiment of the present invention.

10 illustrates waveforms of a signal processor according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100, 200: optical receiving device 210: receiving and amplifying unit

220: HPF unit 230: signal processing unit

240: gain control unit 310: conversion unit

311 photodiode 312 I-V converter

320: amplifier 320a: first amplifier

320b: second amplifier 410: first comparison

420: pulse shaping unit 430: receiving output unit

510: second comparison unit 520: demodulation unit

530: charge / discharge control unit 540: interface unit

610: first level converter 620: inverter

710: second level converting unit 720: first logic gate

730: second logical gate

The present invention relates to an optical receiving apparatus, and more particularly, to an optical receiving apparatus capable of effectively controlling disturbance light noise and receiving only a desired signal normally.

1 shows a conventional optical receiver.

Referring to FIG. 1, the conventional optical receiver 100 includes a photodiode 110 for receiving an optical signal, a current / voltage converter 120 for converting a current of the received optical signal into a voltage, and a weak voltage. Comparing two amplifiers 130a and 130b connected in two stages to amplify two stages, and comparing the amplified voltage with a reference voltage Vref and outputting a comparison signal V_Comp according thereto. The unit 140 includes a pulse shaping unit 150 for shaping the waveform of the comparison signal V_Comp, and a reception output unit 160 for outputting the shaping pulse to the outside.

However, the input signal input to the light receiving device from the outside is not only the desired components, but also unwanted unwanted light such as sunlight is usually input. These disturbances are considered noise components because they are not intended by the designer.

As an example of an infrared signal, a noise waveform of a fluorescent lamp of a general form represents a form of a signal modulated to a power source frequency, and a ballast frequency of the fluorescent lamp is present in a carrier form. The ballast frequency uses dozens of kHz, which overlaps the common infrared frequency band of 2.4 kHz to 115.2 kHz.

In general, in the case of infrared rays directly transmitting a carrier without modulation, it is very difficult to distinguish a normal signal from disturbance light noise.

The normal signal and the disturbance light have a common point in that the carrier frequency is several tens of kHz to 200 kHz. Therefore, a general band pass filter (BPF) does not effectively remove the disturbance light noise, and since the carrier transmission system is not modulated, there is a disadvantage that the disturbance light cannot be removed even by the demodulation method.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical receiving apparatus capable of removing disturbed light noise in a disturbance light environment and receiving only a desired signal normally.

An optical receiving apparatus according to an embodiment of the present invention for achieving the above technical problem includes a receiving and amplifying unit, an HPF unit, a signal processing unit and a gain control unit.

The receiving and amplifying unit converts the received optical signal into a voltage signal and amplifies the voltage signal in response to the gain control signal. The HPF unit passes only a high frequency component among voltage signals output from the receiving and amplifying unit. The signal processor generates a digital data signal using the voltage signal output from the HPF unit. The gain control unit generates the gain control signal using the amplified voltage signal output from the receiving and amplifying unit.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 shows an embodiment of an optical receiving apparatus according to the present invention.

Referring to FIG. 2, the optical receiver 200 includes a receiver and amplifier 210, an HPF unit 220, a signal processor 230, and a gain controller 240.

The receiving and amplifying unit 210 converts an optical signal received from the outside into a voltage signal and amplifies the voltage signal. In this case, the amplification is amplified in response to the gain control signal V_AGC output from the gain control unit 240 which will be described later.

The optical signal received from the outside may be an infrared signal.

The HPF unit 220 passes only a high frequency component of the voltage signal V_G output from the receiving and amplifying unit 210.

The signal processor 230 generates a digital data signal Rx_Data using the voltage signal V_F output from the HPF unit 220 and outputs the digital data signal Rx_Data to the outside of the optical receiver 200.

The gain controller 240 generates a gain control signal V_AGC using the voltage signal V_G amplified by the receiver and amplifier 210 to control the gain of the receiver and amplifier 210.

3 illustrates a receiving and amplifying unit 210 of the optical receiving apparatus 200.

Referring to FIG. 3, the receiving and amplifying unit 210 includes a converter 310 and an amplifier 320.

The converter 310 includes an photodiode 311 for converting an optical signal received from the outside into a current signal and an IV converter 312 for converting the current signal converted in the photodiode 311 into a voltage signal. The signal received from the outside is converted into a voltage signal.

The amplifier 320 includes at least two amplifiers 320a and 320b to amplify the voltage signal output through the converter 310.

In the embodiment of FIG. 3, the amplifier includes a first amplifier 320a for amplifying the voltage signal output through the converter 310 and a second amplifier 320b for amplifying the output signal of the first amplifier 320a. do. Here, the second amplifier 320b amplifies the output signal of the first amplifier 320a with a gain value corresponding to the gain control signal V_AGC.

4 illustrates a signal processor 230 of the optical receiver 200.

Referring to FIG. 4, the signal processor 230 includes a first comparator 410, a pulse shaping unit 420, and a reception output unit 430.

The first comparison unit 410 generates a first comparison signal V_Comp1 by comparing the voltage signal V_F output from the HPF unit 220 with the first reference voltage V_Ref1.

The pulse shaping unit 420 generates a pulse Rx_out corresponding to the first comparison signal V_Comp1 to shape the waveform of the first comparison signal V_Comp1.

The reception output unit 430 outputs the shaped pulse Rx_out output from the pulse shaping unit 420 to the outside of the optical reception device 200.

5 illustrates a gain control unit 240 of the optical receiver 200.

Referring to FIG. 5, the gain controller 240 includes a second comparator 510, a demodulator 520, a charge / discharge controller 530, and an interface 540. do.

The second comparator 510 generates a second comparison signal V_Comp2 by comparing the voltage signal V_G output from the receiving and amplifying unit 210 with the second reference voltage V_Ref2.

Here, the second reference voltage V_Ref2 input to the second comparator 510 may be lower than the first reference voltage V_Ref1 input to the first comparator 410. In this case, the occurrence frequency of the comparison signal V_Comp2 output from the second comparison unit 510 may be higher than the occurrence frequency of the comparison signal V_Comp1 output from the first comparison unit 410.

Although the gain control unit 240 including the second comparator 510 directly uses the voltage signal V_G amplified by the reception and amplification unit 210, the signal processor 230 includes the first comparator 410. In FIG. 2, the voltage signal V_F passed through the HPF unit 220 is used instead of directly using the voltage signal V_G amplified by the receiving and amplifying unit 210.

The demodulator 520 outputs a demodulation signal V_Demo corresponding to the second comparison signal V_Comp2 output from the second comparator 510.

The charge / discharge control unit 530 receives the charge / discharge signals Ch and Dis in response to the demodulation signal V_Demo and the second comparison signal V_Comp2 output from the demodulator 520 and the second comparator 510. Generate.

The interface unit 540 generates the gain control signal V_AGC in response to the charge / discharge signals Ch and Dis output from the charge / discharge control unit 530.

6 illustrates an embodiment of a demodulator 520 of the gain control unit 240.

Referring to FIG. 6, the demodulator 520 includes a first current source I1, a second current source I2, a first switching means SW1, a second switching means SW2, a first capacitor C1, and a first current source I1. The first level converter 610 and the inverter 620 are provided.

One terminal of the first current source I1 is connected to the first power supply voltage VCC, and one terminal of the second current source I2 is connected to the second power source voltage GND.

The first current source I1 and the second current source I2 may be constant current sources. In addition, the first current source I1 may supply a current two to three times larger than the second current source I2.

The first switching means SW1 has one terminal connected to the other terminal of the first current source I1, and the second switching means SW2 has one terminal connected to the other terminal of the first switching means SW1. The other terminal is connected to the other terminal of the second current source I2. Here, the first switching means SW1 and the second switching means SW2 are turned on exclusively of each other.

One terminal of the first capacitor C1 is connected to the common node of the first switching means SW1 and the second switching means SW2, and the other terminal of the first capacitor C1 is connected to the second power supply voltage GND.

The first level converting unit 610 converts a logic level of the signal V_C1 output from the common node of the first switching means SW1 and the second switching means SW2 to convert the demodulation signal V_Demo. Output

The inverter 620 generates a signal for controlling on / off of the first switching means SW1 and the second switching means SW2 in response to the second comparison signal V_Comp2.

An example of the operation of the inverter 620 is as follows.

When the second comparison signal V_Comp2 is "HIGH", a signal for turning on only the first switching means SW1 is generated to charge the first capacitor C1, and the second comparison signal V_Comp2 is generated. In the case of "LOW", a signal for turning on only the second switching means SW2 is generated so that the first capacitor C1 is discharged.

7 illustrates an embodiment of the charge / discharge control unit 530 of the gain control unit 240.

Referring to FIG. 7, the charge / discharge control unit 530 may include a third current source I3, a third switching unit SW3, a second capacitor C2, a second level converter 710, and a first logic gate 720 and a second logic gate 730.

The third current source I3 may be a constant current source, and one terminal is connected to the first power supply voltage VCC.

The third switching means SW3 operates in response to the demodulation signal V_Demo output from the demodulator 520, and one terminal is connected to the other terminal of the third current source I3, and the other terminal is connected to the second terminal. It is connected to the power supply voltage GND.

One terminal of the second capacitor C2 is connected to the common node of the third current source I3 and the third switching means SW3, and the other terminal of the second capacitor C2 is connected to the second power supply voltage GND.

The second level converter 710 converts the logic level of the signal V_C2 output from the common node of the third current source I3 and the third switching means SW3. When the voltage V_C2 of the second capacitor C2 becomes equal to or greater than the threshold voltage of the second level converter 710, the output NOSIG of the second level converter 710 is generated.

The first logic gate 720 generates a discharge signal Dis in response to the output NOSIG of the second level converter 710 and the second comparison signal V_Comp2 output from the second comparator 510. .

The second logic gate 730 generates a charging signal Ch in response to the second comparison signal V_Comp2 output from the second comparator 510 and the demodulation signal V_Demo output from the demodulator 520. . Here, the first logic gate 720 and the second logic gate 730 may be an AND gate.

Therefore, referring to FIG. 7, when the third switching means SW3 is turned off, the second capacitor C2 is charged. On the contrary, when the third switching means SW3 is turned on, the third switching means SW3 is turned on. The second capacitor C2 is discharged.

For example, if the first logic gate 720 and the second logic gate 730 are AND gates, the output NOSIG of the second level converter 710 is "HIGH", and the second comparison signal V_Comp2 is If "LOW", the discharge (DIS) signal is generated by the first logic gate 720. On the other hand, when the second comparison signal V_Comp2 is "HIGH" and the demodulation signal V_Demo is "HIGH", the charging (CH) signal is generated by the second logic gate 730.

8 illustrates an embodiment of the interface unit 540 of the gain control unit 240.

Referring to FIG. 8, the interface unit 540 includes a fourth current source I4, a fifth current source I5, a fourth switching means SW4, a fifth switching means SW5, and a third capacitor C3. do.

One terminal of the fourth current source I4 is connected to the first power supply voltage VCC, and one terminal of the fourth current source I4 is connected to the second power source voltage GND.

The fourth current source I4 and the fifth current source I5 may be constant current sources. In addition, the fourth current source I4 is a charging current source and may supply a larger current than the fifth current source I5 which is a discharge current source.

One terminal of the fourth switching means SW4 is connected to the other terminal of the fourth current source I4. One terminal of the fifth switching means SW5 is connected to the other terminal of the fourth switching means SW4, and the other terminal is connected to the other terminal of the fifth current source I5.

The fourth switching means SW4 and the fifth switching means SW5 may be different types of MOS switches. For example, the fourth switching means SW4 may use a PMOS switch, and the fifth switching means SW5 may use an NMOS switch.

The fourth switching means SW4 operates in response to the charging signal Ch output from the charge / discharge control unit 530, while the fifth switching means SW5 discharges the output from the charge / discharge control unit 530. It operates in response to the signal Dis. Here, the fourth switching means SW4 and the fifth switching means SW5 are turned on exclusively with each other.

One terminal of the third capacitor C3 is connected to the common node of the fourth switching means SW4 and the fifth switching means SW5, and the other terminal of the third capacitor C3 is connected to the second power supply voltage GND.

When the charging signal Ch is output from the charge / discharge control unit 530, the current is charged in the third capacitor C3 through the fourth current source I4. On the other hand, when the discharge signal Dis is output from the charge / discharge control unit 530, the current is discharged to the third capacitor C3 through the fifth current source I5.

As the current is charged / discharged, a voltage corresponding thereto is generated across the third capacitor C3, and the voltage is used as the gain control signal V_AGC of the receiving and amplifying unit 210.

9 illustrates a relationship between a gain control signal V_AGC and a gain of the amplifier 320 according to an embodiment of the present invention.

9, when the voltage across the third capacitor C3 increases, the gain of the amplifier 320 decreases. Therefore, when the disturbance light noise is strong, the gain of the amplifier 320 is reduced to remove the disturbance light noise. On the contrary, it is apparent to those skilled in the art that the control signal can be changed.

10 shows waveforms of the signal processor 230 according to an embodiment of the present invention.

Referring to FIG. 10, in the case of a normal signal, there is almost no difference between the amplifying unit output signal V_G and the HPF unit 220 output signal V_F, and in the case of disturbance light noise, the HPF unit 220 output signal V_F. It can be seen that the waveform of the first comparison signal V_Comp1 output from the first comparison unit 410 is completely different from that of the normal signal due to the decrease in the size of.

Therefore, if the cutoff frequency is appropriately selected by applying the appropriate HPF 220, there is almost no attenuation in the case of the normal signal, and attenuation is increased in the case of the disturbance light noise, thereby effectively removing the disturbance light.

The technical spirit of the present invention has been described above with reference to the accompanying drawings. However, the present invention has been described by way of example only, and is not intended to limit the present invention. In addition, it is apparent that any person having ordinary knowledge in the technical field to which the present invention belongs may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

As described above, the optical receiving apparatus according to the present invention has an advantage in that it normally outputs a signal in the case of a desired signal, and effectively removes the disturbing light in the case of disturbance light noise, thereby improving the noise characteristic of the optical receiving device. .

Claims (18)

A receiving and amplifying unit converting the received optical signal into a voltage signal and amplifying the voltage signal in response to a gain control signal; An HPF unit for passing only a high frequency component among voltage signals output from the receiving and amplifying unit; A signal processor for generating a digital data signal using the voltage signal output from the HPF unit; And And a gain control unit configured to generate the gain control signal using the amplified voltage signal output from the reception and amplification unit. The method of claim 1, wherein the received optical signal, An optical reception device, characterized in that the infrared signal. The method of claim 1, The signal processor includes a first comparator for comparing a voltage signal output from the HPF unit with a first reference voltage, The gain control unit includes a second comparison unit comparing the voltage signal output from the reception and amplification unit with a second reference voltage, And the first reference voltage is higher than the second reference voltage. The method of claim 1, wherein the receiving and amplifying unit, A converting unit converting the received optical signal into a voltage signal; And And an amplifier configured to amplify the voltage signal outputted through the converter by providing at least two amplifiers. The method of claim 4, wherein the conversion unit, A photodiode for converting a received signal into a current signal; And And a current-voltage converter for converting the current signal converted by the photodiode into a voltage signal. The method of claim 4, wherein the amplifying unit, A first amplifier for amplifying the voltage signal output through the converter; And And a second amplifier for amplifying the output signal of the first amplifier with a gain value corresponding to the gain control signal. The method of claim 1, wherein the signal processing unit, A first comparator configured to generate a first comparison signal by comparing the voltage signal output from the HPF unit with a first reference voltage; A pulse shaping unit generating a pulse corresponding to the first comparison signal; And And a reception output unit for buffering the pulse. The method of claim 1, wherein the gain control unit, A second comparison unit configured to generate a second comparison signal by comparing a voltage signal output from the reception and amplification unit with a second reference voltage; A demodulator for outputting a demodulated signal corresponding to the second comparison signal; A charge / discharge controller configured to generate a charge / discharge signal in response to the demodulation signal and the second comparison signal; And And an interface unit generating the gain control signal in response to the charge / discharge signal. The method of claim 8, wherein the demodulation unit, A first current source having one terminal connected to the first power supply voltage; First switching means connected to one terminal of the other terminal of the first current source; A second current source having one terminal connected to the second power supply voltage; Second switching means connected to one terminal of the other terminal of the first switching means, the other terminal of the second current source to the other terminal of the second current source, and exclusively turned on with the first switching means; A first capacitor having one terminal connected to a common node of the first switching means and the second switching means, and the other terminal connected to the second power supply voltage; A first level converting unit converting a logic level of a signal output from a common node of the first switching unit and the second switching unit to output the demodulated signal; And And an inverter for generating a signal for controlling on / off of the first switching means and the second switching means in response to the second comparison signal. The method of claim 9, wherein the first current source, An optical receiving device, characterized in that capable of supplying a current two to three times larger than the second current source. The method of claim 9, wherein the first current source and the second current source, An optical receiving device, characterized in that the constant current source. The method of claim 8, wherein the charge / discharge control unit, A third current source having one terminal connected to the first power supply voltage; Third switching means operable in response to the demodulation signal, one terminal being connected to the other terminal of the third current source, and the other terminal being connected to the second power supply voltage; A second capacitor having one terminal connected to a common node of the third current source and the third switching means, and the other terminal connected to the second power supply voltage; A second level converting unit converting a logic level of a signal output from the common node of the third current source and the third switching means; A first logic gate configured to generate a discharge signal in response to an output of the second level converter and the second comparison signal; And And a second logic gate configured to generate a charging signal in response to the second comparison signal and the demodulation signal. The method of claim 12, wherein the first logic gate and the second logic gate, And an AND gate. The method of claim 12, wherein the third current source, An optical receiving device, characterized in that the constant current source. The method of claim 8, wherein the interface unit, A fourth current source having one terminal connected to the first power supply voltage; Fourth switching means operable in response to the charging signal and having one terminal connected to the other terminal of the fourth current source; A fifth current source having one terminal connected to the second power supply voltage; Operate in response to the discharge signal, one terminal being connected to the other terminal of the fourth switching means, the other terminal being connected to the other terminal of the fifth current source, and exclusively turned to the fourth switching means. Fifth switching means being turned on; And And a third capacitor having one terminal connected to the common node of the fourth switching means and the fifth switching means, and the other terminal being connected to the second power supply voltage. The method of claim 15, wherein the fourth current source, And a current larger than the fifth current source can be supplied. The method of claim 15, wherein the fourth current source and the fifth current source, An optical receiving device, characterized in that the constant current source. The method of claim 15, wherein the fourth switching means and the fifth switching means, Optical receiving device, characterized in that the different type of MOS switch.

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