JP2002314026A - Wide-band amplifier and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide-band amplifier that can amplify signal levels without deteriorating characteristics of signals, and to provide a method of manufacturing the amphfier. SOLUTION: The wide-band amplifier 100 is constituted by flip-chip mounting a field effect transistor 3 on a circuit pattern constituted of the strip conductors 2 of microstrip lines 50 so as to decide the characteristic impedance that decides an estimated band. The gain and group delay characteristic of the amphfier 100 constituted by flip-chip mounting the transistor 3 on the circuit pattern constituted of the strip conductors 2 in a band are adjusted by adjusting the characteristic impedance of the amplifier 100 by trimming the strip conductors 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-band amplifier and a wide-band amplifier for amplifying a signal level without deteriorating the characteristics of the signal in a transmission side system in a communication field which handles a wide band signal such as optical communication. It relates to a manufacturing method.

[0002]

2. Description of the Related Art To transmit a large amount of information in a communication field dealing with a wideband signal, particularly in optical communication, there is a method of transmitting an input signal on the transmission side into a wideband signal by using FM batch modulation and the like. Can be As an example, in the case of a fiber-to-the-home (FTTH) system shown in FIG. 11, an analog image signal and a digital image signal, which are electric signals of several tens of channels, are converted from a signal source 10 into an image signal of a cable television or the like. Be sent. The image signal from the signal source 10 is once FM-modulated in the optical transmission device 11, converted into an optical signal, and transmitted to each home 36 via the optical fiber 14.

FIG. 12 shows the configuration of the optical transmission device 11. The optical transmitter 11 includes an FM modulator 15, a broadband amplifier 16, an electro-optical converter 17, and an optical amplifier 1
8 is provided. The image signal from the signal source 10 in FIG.
12 is FM-modulated by the FM modulator 15 provided in the optical transmitter 11 of FIG.
At 6, the signal is amplified to a signal level required for conversion to an optical signal. The image signal amplified by the broadband amplifier 16 is converted from an electric signal to an optical signal by the electro-optical converter 17, and thereafter, until the intensity of light required to reach each home 36 shown in FIG. The above optical amplifier 1
8 and transmitted.

In order to transmit a signal without deteriorating, it is desirable that the wide-band amplifier 16 has a flat characteristic in which the gain and delay characteristics do not change with respect to the frequency of the signal within the band and take a certain value. It is. In the case of amplifying the FM-modulated signal, as shown in FIG. 13, when the deviation 43b of the group delay characteristic 41b, which is the delay characteristic with respect to frequency, in the band 44 increases, the output signal 42b from the broadband amplifier 16 is FM demodulated. However, reproduction is not performed according to the input signal 40. Therefore, the transmission characteristics of the entire system are significantly deteriorated. In the case of an FM signal used for optical communication, a wide band from about 1 GHz to a maximum of about 11 GHz is required.

Conventionally, a high-frequency amplifier including a wide-band amplifier 16 is constituted by a circuit having a field-effect transistor (FET). The band 44 of the wideband amplifier 16 is determined by the characteristic impedance of the wideband amplifier 16. A packaged FET as a widely used wideband amplifier 16
Those with chips are known. FIG. 14 shows a wideband amplifier 400 including the packaged FET chip 25. FET package 24
The lead 26 is connected to a circuit board 27 on which a circuit pattern is formed by the strip conductor 2 by soldering. In the FET package 24, the electrode of the FET chip 25, which is the main body, and the lead 26 are connected by a wire 29, and the length of the wire 29 and the length of the lead 26 correspond to the wavelength of the signal to be amplified. Therefore, the length is about one-seventh with respect to the wavelength of the signal, where the inductance component cannot be ignored. Therefore, when the wire 29 and the lead 26 are viewed as a transmission line,
A mismatch occurs in the characteristic impedance of the entire circuit that determines the band 44 required for the wideband amplifier 400.

[0006] The mismatch in the characteristic impedance causes peaks in the gain and group delay characteristics at a certain frequency of the wideband amplifier 400. Therefore, in order to compensate for the characteristic impedance mismatch, a chip component 28 such as a chip resistor, a chip capacitor, or a chip coil is mounted on the circuit board 28 so that the characteristic impedance is matched. However, since it is impossible to match the characteristic impedance over a wide band only by mounting the chip component 28, the amount and shape of the solder are changed at the soldering portion such as the lead 26, and the wide band amplifier 400 The characteristic impedance was adjusted so that the band 44 required in the above was obtained.

In the case of the configuration shown in FIG. 14, in the adjustment by soldering, the amount of solder used for the adjustment cannot be quantified, and the adjustment requires time. In addition, since the adjustment method is based on an empirical rule, it cannot be defined, and there is a problem that the adjustment can be made only by a specific person. As a configuration for solving the above problem, as shown in FIG. 15, there is known a wideband amplifier 500 whose circuit is formed by connecting a bare chip FET 30 to an input substrate 7, an output substrate 8 and a chip component 6 by wire bonding. I have. In the broadband amplifier 500 shown in FIG. 15, a bare chip FET 30 is provided on the upper surface of the housing 9 serving as a ground.
The chip component 6, the input board 7, and the output board 8, respectively,
It is mounted by bonding with solder or a conductive adhesive. The FET 30 and the chip component 6 have electrodes only on the upper surface, and the input substrate 7 and the output substrate 8
Are each provided with a strip conductor 2 and are grounded on the upper surface of the housing 9 by a ground conductor 5. Then, the FET 30
The chip component 6, the input board 7, and the output board 8 are connected by wire bonding with wires 35, respectively.

[0008]

In the case of the structure shown in FIG. 15, the length of the wire 35 connecting the components 6, 7, 8, and 30 including the FET 30 is provided in the FET package 24 shown in FIG. The length can be relatively shorter than the sum of the length of the wire 35 and the length of the lead 26. However, also in the configuration shown in FIG. 15, each of the components 6, 7, 8,
The length of the wire 35 connecting the 30 parts is required to be about 1 to 2 mm when there is a difference in height between adjacent parts, and about 0.3 mm even when the height between adjacent parts is the same.
Therefore, the inductance component of the wire 35 cannot be ignored. In the chip resistor 34, which is a kind of the chip component 6 shown in FIG. 16, only the portion 19a of the electrode 19 that sandwiches the resistor 20 functions as a resistor, and other than the portion 19a that sandwiches the resistor 20. The portion 19b to be wire-bonded functions as a coil. This is not limited to the chip resistor 34, and is the same even when the portion corresponding to the resistor 20 is a dielectric in the case of a chip capacitor. Therefore, in addition to the inductance component of the wire 35, the electrode 19 of each component chip 6
Is added to the characteristic impedance of the broadband amplifier 500. When the inductance component is added to the characteristic impedance, peaks may occur in gain and group delay characteristics at a certain frequency. If a peak occurs in the band 44 of the wideband amplifier 500, the characteristic of the signal is degraded when the input signal is amplified.

In the chip resistor 34, since the electrode 19 is disposed only on the upper surface, a potential difference occurs between the electrode 19 and the ground plane 32, and the floating capacitance 33 is formed by the insulator 31 functioning as a dielectric. Occurs. The length in the long axis direction is 1.0 mm,
In the case of a chip resistor having a length in the short axis direction of 0.5 mm and a thickness of 0.35 mm, a stray capacitance of 0.17 pF is present in the calculation. Stray capacitance 33 of chip resistor 34, especially FET
The stray capacitance 33 in the chip resistor 34 for providing feedback from the gate to the drain of 30 not only narrows the band 44 of the broadband amplifier 500, but also results in a peak at a certain frequency for group delay characteristics.

In the structure shown in FIG.
When a plurality of are mounted, if the distance between the components 6, 7, 8, and 30 including the FET 30 is shortened in order to shorten the length of the wire 35, a part of the energy of the signal of the adjacent FET 30 is reduced. Is propagated as an electromagnetic wave to the wire 35 on the input side of the other FET 30, which may cause signal oscillation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a broadband amplifier capable of amplifying a signal level without deteriorating characteristics of a signal in a transmitting system. And a method for manufacturing the wideband amplifier.

[0012]

According to a first aspect of the present invention, there is provided a wide-band amplifier for amplifying a wide-band signal, comprising: a dielectric substrate having a ground conductor; and the ground conductor sandwiching the substrate. A microstrip line formed of a strip conductor forming a circuit pattern, and a field-effect transistor flip-chip mounted on the circuit pattern. A characteristic impedance that determines an assumed band of the broadband amplifier is determined by an inductance component of the field effect transistor.

The line characteristic impedance can be determined by the width of the strip conductor, the thickness and the dielectric constant of the substrate.

The inductance component can be determined by the height of the bump connecting the field effect transistor and the strip conductor.

[0015] The height of the bumps may be such that the characteristic impedance is constituted only by the line characteristic impedance with respect to the wavelength of the high-frequency signal in the broadband signal.

When a plurality of the field-effect transistors are flip-chip mounted on the microstrip line, the connection length between the bumps in the field-effect transistor connection conductor that cascade-connects each of the adjacent field-effect transistors is equal to the second electric field. The energy of the output signal from the effect transistor can be set to a length that does not propagate as electromagnetic waves to the first field-effect transistor.

[0017] A chip resistor for adjusting electric characteristics of the broadband amplifier by being surface-mounted on a circuit pattern formed by the strip conductor may be further provided.

[0018] A resistor portion formed by applying a resistive material on the substrate and connecting the strip conductor to adjust electric characteristics of the wideband amplifier may be further provided.

According to a second aspect of the present invention, there is provided a method of manufacturing a broadband amplifier, comprising: a strip conductor formed of a conductor on a dielectric substrate having a ground conductor and opposed to the ground conductor with the substrate interposed therebetween. Form the circuit pattern of the microstrip line with and determine the characteristic impedance of the wideband amplifier that determines the band of the wideband amplifier,
A field effect transistor is flip-chip mounted on the circuit pattern.

In forming the circuit pattern, the strip conductor is formed on the substrate whose thickness and permittivity are determined so that the line characteristic impedance of the microstrip line becomes the characteristic impedance of the wide band amplifier. be able to.

Before flip-chip mounting the field-effect transistor, the height of the bump connecting the strip conductor and the field-effect transistor is determined by the inductance component added to the line characteristic impedance with respect to the wavelength of a high-frequency signal. Can be formed to have a negligible height.

After the field effect transistor is flip-chip mounted to form the broadband amplifier, the strip conductor may be trimmed to change the width and shape to adjust the characteristic impedance of the wideband amplifier.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wide-band amplifier and a method of manufacturing a wide-band amplifier according to embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same members are denoted by the same reference numerals. 1 and 2 show a configuration of a wideband amplifier 100 according to a first embodiment of the present invention. The broadband amplifier 100 is formed on a dielectric substrate 1 having a ground conductor 5 on its lower surface, and is a flat strip conductor 2 parallel to the ground conductor 5, and a field effect transistor (FET) 3 as a bare chip. And The substrate 1, the strip conductor 2, and the ground conductor 5 form a microstrip line 50. The FET 3 is flip-chip mounted on a circuit pattern formed by the strip conductor 2, and as shown in FIG. 10, a bump 4 formed on an electrode surface 3 c of the FET 3 and the strip conductor 2 It is mounted by bonding with a conductive adhesive 45 or the like.
In addition, a generally used square chip resistor 21 is surface-mounted on the circuit pattern as a resistor required to adjust the electrical characteristics of the circuit constituting the wideband amplifier 100. The broadband amplifier 100 is used for optical communication, and has a frequency of about 1 GHz to a maximum of 11 GHz.
The characteristic impedance of the wideband amplifier 100 is determined so that a wideband signal up to a high frequency signal of about z can be amplified. The characteristic impedance of the broadband amplifier 100 is defined by the line characteristic impedance which is the characteristic impedance of the microstrip line 50 and the bump 4 of the FET 3 mounted on the flip chip.
And the inductance component.

The wideband amplifier 100 has a maximum of 11 GHz.
In order to amplify a wideband signal up to a high frequency signal of about z, the substrate 1 uses a high frequency substrate such as a ceramic substrate. The width 2 a of the strip conductor 2, the thickness 1 a of the substrate 1, and the permittivity are such that the line characteristic impedance, which is the characteristic impedance of the microstrip line 50, is 1 GHz.
It is designed to take the characteristic impedance of the broadband amplifier 100 from about z up to about 11 GHz. The width 2a of the strip conductor 2 is designed to keep a constant value so that the line characteristic impedance does not change on the way.

The height 4a of the bump 4 connecting the FET 3 and the strip conductor 2 shown in FIG.
Is about 50-60 μm, and is 10 GHz
Is about 1/150 with respect to the wavelength of the high-frequency signal. Conversely, the height 4a of the bump 4 is such that the inductance component can be sufficiently ignored for a high-frequency signal.

Further, since the chip resistor 21 is surface-mounted on the circuit pattern formed by the strip conductor 2, almost no potential difference occurs between the electrodes of the chip resistor 21. Therefore, the stray capacitance 33 can be suppressed more than the chip resistor 34 having the electrode 19 only on the upper surface shown in FIG.

The line characteristic impedance is substantially determined by the width 2a of the strip conductor 2, the thickness 1a of the substrate 1, and the dielectric constant of the substrate 1. Therefore, in the microstrip line 50, the change in the signal transmittance and the delay due to the change in the signal frequency hardly occurs. Further, since the inductance component of the bump 4 added to the line characteristic impedance is sufficiently negligible, mismatching of the characteristic impedance in the wideband amplifier 100 hardly occurs. Therefore, in the wideband amplifier 100, factors that impair the flatness of the gain and group delay characteristics in the band are almost eliminated. In addition, by regarding the line characteristic impedance as the characteristic impedance of the wideband amplifier 100, the wideband amplifier 100 having a band from about 1 GHz to a maximum of about 11 GHz can be easily configured. In addition, since the stray capacitance generated in the chip resistor 21 can be suppressed, the band of the broadband amplifier 100 can be widened, and the occurrence of a peak in the group delay characteristic can be suppressed. Therefore, the wideband amplifier 1
In the case of 00, the signal level in the band can be amplified without deteriorating the characteristics of the signal.

FIG. 3 shows a strip conductor 2 according to the first embodiment.
Broadband amplifier 1 with flip chip mounted FET3
00 and FE by the conventional wire bonding shown in FIG.
It is a comparison of the simulation result of the gain with the wideband amplifier 500 to which T3 is connected. Also, FIG.
Simulation results of group delay characteristics of the wideband amplifier 100 in which the FET 3 is flip-chip mounted on the strip conductor 2 of the first embodiment and the conventional wideband amplifier 500 to which the FET 3 is connected by wire bonding shown in FIG. It is. As shown in FIG. 3, in the conventional wideband amplifier 500, a peak occurs in the gain near 12 GHz, but in the wideband amplifier 100 according to the first embodiment of the present invention, no peak occurs in the gain. In addition, as shown in FIG.
, The group delay characteristic shows an increase from around 6 GHz,
A peak occurs around GHz. However, in the broadband amplifier 100 according to the first embodiment of the present invention, 1 GHz
In a wide band from about z to about 11 GHz, the group delay characteristic becomes flat. Accordingly, it is understood that the wideband amplifier 100 according to the first embodiment of the present invention can amplify a signal in a band required for optical communication without deteriorating the characteristics of the signal.

The microstrip line 50 is
The strip conductor 2 and the ground conductor 5 may be formed facing each other with the substrate 1 interposed therebetween.
May be arranged on the upper surface of the substrate 1, and the strip conductor 2 may be arranged on the lower surface of the substrate 1. In addition, the broadband amplifier 100 can be used as an amplifier circuit in a high-frequency measuring device such as an oscilloscope other than the optical communication, and the width 2a of the strip conductor 2, the thickness 1a of the substrate 1, and the dielectric The ratio may be designed according to the band of the signal to be used. Also, the height 4a of the bump 4
Is not limited to about 50 to 60 μm as long as the inductance component can be negligible with respect to the wavelength of the signal. Further, the bump 4 may be formed on the strip conductor 2 side. In addition, the above chip resistor 21
Is sufficient as long as it can suppress the generation of stray capacitance, so long as it can be surface-mounted on the circuit pattern formed by the strip conductor 2. Also, if a resistor is not required in the circuit configuring the wideband amplifier 100,
The chip resistor 21 need not be provided.

As a modification of the broadband amplifier 100 of the first embodiment, a resistor material is applied on the substrate 1 as shown in FIGS. 5 and 6 instead of the chip resistor 21 shown in FIGS. May be provided.
Since the resistor portion 22 is formed as a part of a circuit pattern formed by the strip conductor 2, the resistor portion 22 functions as a resistor necessary for a circuit in order to adjust electric characteristics of the broadband amplifier 200. The resistor section 22 has the same effect on the stray capacitance as the chip resistor 21 shown in FIGS. Further, by forming the resistor portion 22 before mounting, it is not necessary to mount the chip resistor 21, and it is possible to reduce the number of components at the time of mounting.

Next, a method of manufacturing the wideband amplifier 100 shown in FIGS. 1 and 2 will be described below. First,
The band of the signal to be amplified by the broadband amplifier 100 is 1
The broadband amplifier 1 determines the band from about GHz to about 11 GHz, and determines the band of the broadband amplifier 100.
The characteristic impedance of 00 is determined. Next, the thickness 1a and the dielectric constant of the substrate 1 provided with the ground conductor 5 are determined so that the line characteristic impedance takes the characteristic impedance of the broadband amplifier 100. A circuit pattern is formed by the strip conductor 2 so as to correspond to the dielectric constant. Next, the FET 3 of a bare chip, formed so that the height 4a of the bump 4 is unified to about 50 to 60 μm, is flip-chip mounted on the circuit pattern. During the mounting operation, the chip resistor 21 is also surface-mounted. As described above, the FET is placed on the circuit pattern formed by the strip conductor 2 of the microstrip line 50 so as to determine the characteristic impedance of the broadband amplifier 100 which determines the assumed band of the wideband amplifier 100.
The mounting method for flip-chip mounting 3 is referred to as characteristic impedance determining mounting. Further, in the microstrip line 50 on which the mounting for determining the characteristic impedance is performed, each value of the thickness, the dielectric constant, and the width 2a of the strip conductor 2 is set to a value that satisfies the characteristic impedance. Therefore, the elements controlled to satisfy the characteristic impedance determination mounting are the bumps 4
Height 4a.

Since the line characteristic impedance is determined by the width 2a of the strip conductor 2, the thickness 1a of the substrate 1, and the dielectric constant, the strip conductor 2 is trimmed by a laser trimming device 23 shown in FIG. By changing the width 2a and the shape of the strip conductor 2, the line characteristic impedance can be adjusted. Further, since the inductance component of the bump 4 is sufficiently negligible and the stray capacitance generated in the chip resistor 21 is suppressed, the gain and group delay characteristics in the band of the broadband amplifier 100 are determined by the line characteristics. Mostly determined by impedance. Therefore, by adjusting the line characteristic impedance, it is possible to adjust the gain and group delay characteristics within the band of the wideband amplifier 100.

The resistor 22 shown in FIG. 5 and FIG.
Trimming with the laser trimming device 23 shown in
By changing the width and shape of the resistor section 22, it is also possible to widen the range of adjusting the gain and group delay characteristics within the band in the wideband amplifier 100. Further, by automating the trimming of the strip conductor 2 or the trimming of the resistor portion 22 shown in FIGS. 5 and 6, the time required for adjusting the broadband amplifier 100 can be reduced. The trimming process may be performed by using a device other than the laser trimming device 23. However, even when the width 2a and the shape of the strip conductor 2 change very little, the line characteristic impedance greatly changes. It is desirable to use the above-mentioned laser trimming device 23 capable of performing a perfect trimming.

[0034] Broadband amplifier 100 in the first embodiment
Then, one FET3 amplifies the wideband signal,
A wideband signal may be amplified using a plurality of FETs 3.
FIGS. 8 and 9 show the structure of the broadband amplifier 300 according to the second embodiment of the present invention. 8 and 9
As shown in FIG. 2, in the wideband amplifier 300, two adjacent FETs 3 are cascaded via the strip conductor 2. Here, first, a wideband signal is input.
The first-stage FET 3 is defined as a first FET 3 a, and the first FET 3 a
2nd stage FET to which the wideband signal amplified by is input
3 is a second FET 3b. The strip conductor 2b connecting the first FET 3a and the second FET 3b is a field effect transistor (FET) connection conductor. still,
The height 4a of the bump 4, the width 2a of the strip conductor 2, and the thickness 1 of the substrate 1 of the broadband amplifier 300 in the second embodiment.
Other configurations such as a, dielectric constant, signal band, and the like are the same as those of the broadband amplifier 100 in the first embodiment.

The first FE in the FET connection conductor 2b
The length 2c from the connection point of the bump 4 of T3a to the connection point of the bump 4 of the second FET 3B is set to 2 mm or more.
By providing a sufficient distance between the FET 3a and the second FET 3b, part of the energy of the output signal amplified by the second FET 3b is converted into electromagnetic waves by the first FET 3a.
The bump 4 and the microstrip line 50 on the input side of FIG.
Transmission lines 40a and 40b, in particular, the first FET
Oscillation of a signal caused by propagation to the transmission line 40b connected to the gate of 3a can be suppressed. Hereinafter, the length 2c between the connection point of the bump 4 of the first FET 3a and the connection point of the bump 4 of the second FET 3B in the FET connection conductor 2b is referred to as a connection length between bumps.

The number of FETs 3 provided in the wideband amplifier 300 is not limited to two. That is, more FETs 3 may be cascaded in series to further amplify the output signal. Further, a plurality of FETs 3 may be connected in cascade to one FET 3. Further, the inter-bump connection length 2c in the FET connection conductor 2b connecting the plurality of FETs 3 must be a length such that part of the energy of the signal of each adjacent FET 3 does not propagate as an electromagnetic wave to each other. If the amplification factor of the output signal in each FET 3 increases, the energy of the output signal also increases, and the electromagnetic wave that is a part of the energy of the output signal also increases. Therefore, the inter-bump connection length 2c of the FET connection conductor 2b is longer than 2 mm. When a plurality of FETs 3 are provided, the chip resistor 21 shown in FIGS. 1 and 2 is mounted on a circuit pattern formed by the strip conductor 2 as a necessary resistor in the circuit of the broadband amplifier 300. Alternatively, the strip conductor 2 may be connected to the resistor 22 shown in FIGS. Further, the gain and group delay characteristics within the band of the wideband amplifier 300 may be adjusted by trimming the strip conductor 2 and adjusting the characteristic impedance. The wideband amplifier 400 according to the second embodiment may also be used to amplify a wideband signal other than optical communication, similarly to the wideband amplifier 100 according to the first embodiment.

[0037]

According to the wide-band amplifier according to the first aspect of the present invention and the method of manufacturing the wide-band amplifier according to the second aspect of the present invention, a microstrip line having a circuit pattern formed by strip conductors, a field effect transistor, Constitutes the wideband amplifier. At this time, the field effect transistor is placed on the circuit pattern so that the characteristic impedance of the wide band amplifier that determines the band of the wide band amplifier is determined by the line characteristic impedance of the microstrip line and the inductance component of the field effect transistor. Flip chip mounting. Therefore, since the gain and group delay characteristics are flat in the band determined by the characteristic impedance, the wideband amplifier manufactured using the method described above does not deteriorate the characteristics of the signal in the band. Can be amplified.

Further, the width of the strip conductor is set so that the line characteristic impedance of the microstrip line takes the characteristic impedance of the wide band amplifier.
By determining the thickness and dielectric constant of the substrate on which the strip conductor is provided, it is possible to eliminate changes in signal transmittance and delay due to changes in signal frequency in the microstrip line. Further, the wideband amplifier can be easily configured by regarding the line characteristic impedance as the characteristic impedance of the wideband amplifier. Further, since the inductance component is determined by the height of the bump connecting the field-effect transistor and the strip conductor, the height of the bump is determined by the characteristic impedance with respect to the wavelength of the high-frequency signal in the broadband signal. By setting the height to be constituted only by the line characteristic impedance, it is possible to make the characteristic impedance mismatch in the broadband amplifier hardly occur. Therefore, by using the above-described configuration, it becomes easy to configure a wideband amplifier capable of amplifying without deteriorating characteristics of a signal in the band.

When a plurality of the field effect transistors are flip-chip mounted on the strip conductor,
The connection length between the bumps in the field-effect transistor connection conductor that cascade-connects the adjacent first and second field-effect transistors is set to a length that does not allow the electromagnetic waves generated by the second field-effect transistor to propagate to the first field-effect transistor. Thus, oscillation of the broadband signal can be suppressed.

Further, by mounting a chip resistor for adjusting the electrical characteristics of the broadband amplifier on the surface of the circuit pattern, it is possible to suppress the generation of stray capacitance in the chip resistor. Therefore, it is possible to widen the band in the wideband amplifier, and it is possible to suppress the occurrence of a peak in the group delay characteristic. Further, the same effect as the above-described chip resistor can be obtained even if the resistor portion is formed of a resistor material applied on the substrate as a part of the circuit pattern instead of the above-described chip resistor.

Also, by adjusting the characteristic impedance of the wide band amplifier by trimming the strip conductor, the gain and group delay characteristics within the band of the wide band amplifier can be adjusted.

[Brief description of the drawings]

FIG. 1 is a perspective view of a broadband amplifier according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of the broadband amplifier shown in FIG.

3 is a graph showing gain simulation results of the wideband amplifier shown in FIG. 1 and the conventional wideband amplifier shown in FIG.

4 is a graph showing simulation results of group delay characteristics of the wideband amplifier shown in FIG. 1 and the conventional wideband amplifier shown in FIG.

FIG. 5 is a perspective view of a modification of the broadband amplifier shown in FIG. 1;

6 is a sectional view taken along line VI-VI of a modification of the wideband amplifier shown in FIG.

FIG. 7 is a perspective view of the broadband amplifier showing a method of adjusting the wideband amplifier shown in FIG. 1;

FIG. 8 is a perspective view of a broadband amplifier according to a second embodiment of the present invention.

FIG. 9 is a sectional view taken along line IX-IX of the broadband amplifier shown in FIG.

FIG. 10 is an enlarged sectional view of a bump of a field-effect transistor provided in the broadband amplifier shown in FIG. 2;

FIG. 11 is a process chart showing a signal transmission process in the FTTH system.

FIG. 12 is a process chart showing a signal conversion process in the optical transmission device provided in the FTTH system shown in FIG. 11;

FIG. 13 is an explanatory diagram illustrating a relationship between a group delay characteristic, an input signal, and an output signal.

FIG. 14 is a sectional view of a conventional wideband amplifier.

15 is a cross-sectional view of a conventional wide-band amplifier, which is an improved example of the wide-band amplifier shown in FIG.

FIG. 16 is a perspective view of a chip resistor, which is a kind of chip component provided in the broadband amplifier shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... Substrate thickness, 2 ... Strip conductor, 2
a: width of strip conductor, 2b: field effect transistor connection conductor, 2c: length of field effect transistor connection conductor, 3: field effect transistor, 3a: upper field effect transistor, 3b: lower field effect transistor, 4,
... Bumps, 5 ground conductors, 21 chip resistors, 22 resistance sections, 50 microstrip lines, 100 broadband amplifiers.

Continuation of front page (72) Inventor Katsuya Oda 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] A wide band amplifier (1) for amplifying a wide band signal.
00), a substrate (1), which is a dielectric having a ground conductor (5), and a strip conductor (2) which is opposed to the ground conductor with the substrate interposed therebetween and which forms a circuit pattern. A strip line (50), and a field effect transistor (3) flip-chip mounted on the circuit pattern, wherein a line characteristic impedance of the microstrip line and an inductance component of the field effect transistor
A wide-band amplifier, which determines a characteristic impedance that defines an assumed band of the wide-band amplifier. 2. The line characteristic impedance is defined by a width (2a) of the strip conductor and a thickness (1a) of the substrate.
The wideband amplifier according to claim 1, wherein the wideband amplifier is determined by: 3. The wideband amplifier according to claim 1, wherein said inductance component is determined by a height (4a) of a bump (4) connecting said field effect transistor and said strip conductor. 4. The wide band amplifier according to claim 3, wherein the height of the bump is such that the characteristic impedance is constituted only by the line characteristic impedance with respect to the wavelength of the high frequency signal in the wide band signal. . 5. A field effect transistor which cascade-connects adjacent first and second field effect transistors when a plurality of the field effect transistors are flip-chip mounted on the strip conductor. The connection length between bumps (2c) in the connection conductor (2b) is a length that does not allow energy of an output signal from the second field-effect transistor to propagate as electromagnetic waves to the first field-effect transistor. The wideband amplifier according to any one of the above. 6. The device according to claim 1, further comprising a chip resistor (21) that is surface-mounted on a circuit pattern formed by the strip conductor to adjust an electrical characteristic of the broadband amplifier. The wide-band amplifier according to 1. 7. A resistor part (22) formed as a part of the circuit pattern by applying a resistive material on the substrate and adjusting an electrical characteristic of the broadband amplifier. The wideband amplifier according to any one of the above. 8. A strip conductor (2) of a microstrip line (50) formed on a dielectric substrate (1) having a ground conductor (5) and facing the ground conductor with the substrate interposed therebetween. Forming a circuit pattern with the circuit pattern, and flip-chip mounting a field effect transistor (3) on the circuit pattern so as to determine a characteristic impedance of the wide band amplifier (100). . 9. When forming the circuit pattern, the microstrip line has a characteristic impedance of the broadband amplifier on the substrate whose thickness (1a) and permittivity are determined. The method for manufacturing a broadband amplifier according to claim 8, wherein a strip conductor is formed. 10. The bump (4) connecting the strip conductor and the field effect transistor before the field effect transistor is flip-chip mounted.
The method according to claim 8 or 9, wherein a) is formed such that an inductance component added to the line characteristic impedance has a negligible height with respect to a wavelength of a high-frequency signal. 11. The wide-band amplifier is formed by flip-chip mounting the field-effect transistor, and then the strip conductor is trimmed to change the width (2a) and shape, thereby adjusting the characteristic impedance of the wide-band amplifier. The method for manufacturing a broadband amplifier according to claim 8, wherein