JP2001345606A - Mmic amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem raised in a conventional MMIC that the conductor widths of lines realizing the same impedance become broader and peripheral circuits widely occupy a semiconductor substrate, because the dielectric substrate related to the peripheral circuits excluding an element section is formed thicker. SOLUTION: An MMIC amplifier is provided with the dielectric substrate 6, an amplifier 2 formed on the substrate 6, a matching circuit composed of an input matching circuit 4 and output matching circuit 5, and formed on the substrate 6. The MMIC amplifier is also provided with a recessed section 7 which is formed by removing the part of the substrate 6 under the whole or partial area of the matching circuit, and a grounding conductor 8 formed on the back side of the substrate 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an MMIC amplifier used in a microwave or millimeter wave band.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a cross-sectional view illustrating a configuration of a conventional MMIC (monolithic microwave IC) described in Japanese Patent Publication No. FIG.
FIG. 2 is a plan view showing the same configuration of the MMIC as in FIG.
11 and 12, reference numeral 101 denotes an input line;
2 is an input matching stub, 103 is a first stage FET, 10
4 is a substrate thin layer portion, 105 is a matching stub between steps, 10
6 is a capacitor, 107 and 108 are bias terminals, 10
9 is an interstage line, 110 is a latter-stage FET, 111 is a substrate thin layer portion, 112 is an output matching stub, 113 is an output line, 114 is a semiconductor substrate, 115 is a gate electrode, 116
Is a source electrode, 117 is a drain electrode, 118 is an active layer, and 119 is a back surface conductor.

Next, the operation will be described. Input line 10
1 is input to the first-stage FET 103 via the input matching circuit having the matching stub 102, and the signal is transmitted to the first-stage FET 103 and the second-stage FET 110 having the inter-stage matching stub 105 and the like. The amplified signal is then output to the output line 113.

[0004] As shown in FIG.
In this method, the entire MMIC is formed of a semiconductor substrate having a thickness of 100 μm or more, and only the substrate of the element portion is reduced to a thickness of several tens μm or less by partial etching or the like. Thereafter, the back surface conductor is filled by plating or the like to form the entire circuit. By forming the entire MMIC with a semiconductor having a thickness of 100 μm or more, circuit loss is reduced. On the other hand, by making the substrate thickness of the peripheral circuit larger than the substrate thickness of the element portion, the conductor width of the line does not become extremely thin, and an increase in the line loss can be suppressed. Further, the back conductor 119 is located very close to the heating region of the FET.
, A good heat sink is formed.

FIG. 13 shows, for example, Japanese Patent Application Laid-Open No. 6-2371.
FIG. 5 is a cross-sectional view illustrating a configuration of a conventional MMIC described in Japanese Patent Publication No. 05-2005. In FIG. 13, 121 is a metal case, 1
Reference numeral 21a denotes a protrusion formed at the center of the bottom surface of the metal case 121, 122 denotes a dielectric substrate, 123 denotes a concave portion formed in the dielectric substrate 122, and 124 denotes an active element mounted on the protrusion 121a. A high dielectric constant dielectric substrate 122 entirely formed of the same material is soldered to a metal substrate portion on the inner bottom surface of the metal case 121. In the dielectric substrate 122, the characteristic impedance of the microstrip line formed on the upper surface of the dielectric substrate 122 above the portion where the concave portion 123 is formed is the characteristic impedance of the dielectric substrate 122 where the concave portion 123 is not formed. Compared with the characteristic impedance of the microstrip line formed on the upper surface, the line width can be increased even if the line width is the same.

[0006]

SUMMARY OF THE INVENTION For example, Japanese Patent Application Laid-Open No. 62-8 / 1987
The conventional MMIC described in Japanese Patent No. 6850 has a configuration in which the thickness of the substrate other than the element portion is set to 100 μm or more and the thickness of the substrate of the element portion is set to a thickness of several tens μm or less. The increase is suppressed. However, although the loss is reduced, the conductor width of the line for realizing the same impedance is increased, so that there is a problem that an expensive semiconductor substrate is occupied widely as compared with the case where the substrate thickness is small.

Also, for example, the conventional MMIC described in Japanese Patent Application Laid-Open No. Hei 6-237105 has a structure in which a concave portion is provided in a dielectric substrate to partially increase the characteristic impedance of a microstrip line. . However, since the space of the concave portion of the dielectric substrate is a cavity, solder or the like enters the concave portion of the dielectric substrate when the dielectric substrate is bonded, so that there is a problem that the characteristic impedance fluctuates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a miniaturized MMIC by reducing the thickness of a peripheral circuit board.

It is another object of the present invention to obtain an MMIC in which a concave portion of a dielectric substrate is filled with a filling material so that the characteristic impedance and the like do not fluctuate.

[0010]

An MMIC according to the present invention is provided.
The amplifier includes a dielectric substrate, an amplifier formed on the dielectric substrate, a matching circuit including an input matching circuit and an output matching circuit formed on the dielectric substrate, and an entire region or a partial region below the matching circuit. One or more concave portions formed by removing a part of the dielectric substrate below the entire region or the partial region of the matching circuit so as to reduce the substrate thickness of the dielectric substrate;
And a ground conductor provided on the back side of the dielectric substrate at least in a region other than the region where the concave portion is formed.

An MMIC amplifier according to the present invention is formed by removing a part of the dielectric substrate below the stub so as to selectively reduce the thickness of the dielectric substrate below the stub constituting the matching circuit. And one or more concave portions having a ground conductor on the outer surface.

The MMIC amplifier according to the present invention is formed by removing a part of the dielectric substrate below the microstrip lines so as to reduce the thickness of the dielectric substrate below the microstrip lines constituting the matching circuit. And one or more recesses having a ground conductor on the outer surface.

In the MMIC amplifier according to the present invention, the thickness of the dielectric substrate below a part of the microstrip lines constituting the matching circuit is reduced so as to reduce the thickness of the dielectric substrate. It is formed by removing a part of the dielectric substrate, and has one or a plurality of concave portions having a ground conductor on an outer surface portion.

The MMIC amplifier according to the present invention is formed by removing a part of the dielectric substrate below the capacitor so as to reduce the thickness of the dielectric substrate below the capacitor constituting the matching circuit, and includes a ground conductor. One or more concave portions are provided.

The MMIC amplifier according to the present invention uses an interdigital capacitor as a capacitor.

The MMIC amplifier according to the present invention is formed by removing a part of the dielectric substrate below the inductor so as to reduce the thickness of the dielectric substrate below the inductor constituting the matching circuit, and includes a ground conductor. One or more concave portions are provided.

In the MMIC amplifier according to the present invention, the concave portion is filled with an insulating filler having a lower dielectric constant than the dielectric substrate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a plan view and a sectional view showing an MMIC amplifier according to a first embodiment of the present invention. FIG.
, 1 is an input terminal, 2 is a transistor, 3 is an output terminal, 4 is an input matching stub, 5 is an output matching stub, 6 is a dielectric substrate, and 7 is formed by removing a part of the dielectric substrate 6. The recessed portion 8 is a ground conductor provided on the back surface of the dielectric substrate 6. As a schematic configuration,
An input matching circuit including the input matching stub 4, an amplifier including the transistor 2, and an output matching circuit including the output matching stub 5 are provided. The output matching circuit is arranged on the concave portion 7 and is provided on the dielectric substrate 6 which is thinner than the portion where the input matching circuit and the amplifier are arranged.

FIG. 2 is a diagram showing the relationship between the substrate thickness of a dielectric substrate and the line width of a microstrip line formed on the substrate. FIG. 2 shows the line width of the 50 ohm line calculated according to the substrate thickness. As shown in FIG. 2, the line width of the 50-ohm line increases in proportion to the substrate thickness of the dielectric substrate. Therefore, by reducing the thickness of the dielectric substrate at the position where the matching circuit is disposed, the width of the line that achieves the same impedance is reduced, and a plurality of stubs can be disposed close to each other. Further, by reducing the thickness of the substrate, the electric field generated between the microstrip line and the ground conductor on the back surface can be confined in a narrow range, so that the coupling between the lines arranged in parallel is reduced, The isolation between lines can be increased.

As described above, according to the first embodiment, since the thickness of the dielectric substrate at the portion where the matching circuit is disposed is reduced, the microstrip lines constituting the matching circuit are the same. Since the width of the line for realizing the impedance can be reduced and the isolation between the lines can be increased, there is an effect that the circuit area can be reduced and the circuit can be downsized by high-density mounting. In addition, in the case of the same circuit area, there is an effect that the degree of freedom of mounting can be increased by reducing the width of the line.

Embodiment 2 FIG. FIG. 3 is a plan view and a sectional view showing an MMIC amplifier according to a second embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. 5 ₁ and 5 ₂ correspond to the output matching stubs (stubs) formed separately, and 7 ₁ and 7 ₂ correspond to the output matching stubs 5 ₁ and 5 ₂ , respectively, and a part of the dielectric substrate 6 is removed. This is a concave portion formed by doing so. Incidentally, as shown in FIG. 3, the outer surface of the recess 7 _1, 7 ₂ is grounded conductor 8 is provided.

[0022] As described above, in the dielectric substrate 6, the output matching stub 5 _1, 5 ₂ by forming the recesses 7 _1, 7 ₂ at a site is located, to reduce the substrate thickness of the output matching stub bottom Thus, the line width can be reduced, and the lines can be prevented from overlapping each other.
In other parts, the line width can be kept large, so that loss can be suppressed.

As described above, according to the second embodiment, since the thickness of the dielectric substrate at the portion where the output matching stub is arranged is selectively reduced, the impedance of the output matching stub is the same. It is possible to reduce the line width of the microstrip line that realizes the above, and it is possible to increase the degree of freedom relating to the arrangement of the output matching stub, and to maintain the line width of other parts as large, This has the effect of suppressing loss.

In the second embodiment, the concave portion is formed below the portion where the output matching stub is arranged. However, the concave portion is formed so as to reduce the thickness of the dielectric substrate between the microstrip lines. May be formed. FIG. 4 is a block diagram showing M according to the second embodiment of the present invention.
FIG. 11 is a cross-sectional view illustrating a modified example of the MIC amplifier. In FIG. 4, reference numeral 11 denotes a microstrip line, 12 denotes a concave portion formed so as to be located between the microstrip lines 11, and E denotes a line of electric force.

As described above, by reducing the substrate thickness between the microstrip lines, the microstrip line 1
Since the electric field generated between the first and the ground conductors 8 on the back side can be confined in a narrow range, the coupling between the microstrip lines can be reduced, and the effect of increasing the isolation between the lines can be obtained. Play.

Embodiment 3 FIG. FIG. 5 is a plan view and a sectional view showing an MMIC amplifier according to a third embodiment of the present invention. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. 21 is a microstrip line formed in a meandering shape on the dielectric substrate 6,
Reference numeral 22 denotes a concave portion formed by removing a part of the dielectric substrate 6 below the partial region so as to correspond to the partial region of the microstrip line 21 divided into a strip. As shown in FIG. 5, the ground conductor 8 is provided on the outer surface of the recess 22.

Since the substrate thickness of the dielectric substrate 6 is reduced on the concave portion 22, the characteristic impedance of the microstrip line formed above the concave portion 22 is reduced. The same electrical characteristics as when the line width of the microstrip line in the region is increased can be obtained.

As described above, according to the third embodiment, since the concave portion 22 is formed so as to correspond to the partial region of the microstrip line 21, the microstrip line formed in the partial region is formed. Since the same electrical characteristics as those obtained by widening the line width can be obtained, there is an effect that a filter circuit can be formed by using the electrical characteristics.

Embodiment 4 FIG. 6 is a plan view and a sectional view showing an MMIC amplifier according to a fourth embodiment of the present invention. 6, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. 31 is an MIM capacitor (capacitor) formed on the dielectric substrate 6,
Reference numeral 32 denotes a concave portion formed by removing a part of the dielectric substrate 6 so as to correspond to the MIM capacitor 31.

The dielectric substrate 6 below the MIM capacitor 31
Is removed to form the recess 32 having no ground conductor 8, the distance between the lower electrode portion of the MIM capacitor 31 and the ground conductor 8 can be increased. Furthermore, since the space below the MIM capacitor 31 is filled with air having a relative dielectric constant lower than that of the dielectric substrate 6, the parasitic capacitance of the MIM capacitor 31 is reduced.

As described above, according to the fourth embodiment, a part of the dielectric substrate 6 below the MIM capacitor 31 is removed to form the recess 32 without the ground conductor 8. The parasitic capacitance of the MIM capacitor 31 can be reduced, and the effect of improving the reliability of the circuit operation of the MMIC can be obtained.

Embodiment 5 FIG. 7 is a plan view and a sectional view showing an amplifier according to a fifth embodiment of the present invention.
7, the same reference numerals as those in FIG. 6 denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 41 denotes an insulating filler filled in the recess 32 having no ground conductor 8 and having a lower relative dielectric constant than the dielectric substrate 6.

By filling the concave portion 32 formed in the dielectric substrate 6 with the insulating filler 41, it is possible to prevent solder, adhesive or the like from entering the concave portion 32 when the dielectric substrate 6 is mounted. be able to.

As described above, according to the fifth embodiment, the relative permittivity is lower than that of the dielectric substrate 6 in the concave portion 32 formed by removing a part of the dielectric substrate 6 below the MIM capacitor 31. Since the configuration is such that the low insulating filler 41 is filled, the parasitic capacitance of the MIM capacitor 31 can be reduced, and the variation of the characteristic impedance can be suppressed by preventing the penetration of the solder or the like into the recess 32. This has the effect that it can be performed.

Embodiment 6 FIG. FIG. 8 is a plan view and a sectional view showing a configuration of an MMIC amplifier according to a sixth embodiment of the present invention. 8, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 51 denotes an interdigital capacitor (capacitor) formed on the dielectric substrate 6. Reference numeral 52 denotes a concave portion formed by removing a part of the dielectric substrate 6 so as to correspond to the interdigital capacitor 51.

By removing a part of the dielectric substrate 6 below the interdigital capacitor 51 to form a concave portion 52 having no ground conductor 8, the distance between the electrode portion of the interdigital capacitor 51 and the ground conductor 8 is reduced. Can be increased. Further, the interdigital capacitor 51
Since the lower space is filled with air having a relative dielectric constant lower than that of the dielectric substrate 6, the parasitic capacitance of the interdigital capacitor 51 is reduced. Further, by increasing the distance between the electrode portion of the interdigital capacitor 51 and the ground conductor 8, the electric field generated between the microstrip line forming the interdigital capacitor 51 and the ground conductor 8 is opened to a wide range. Therefore, a larger coupling amount of the interdigital capacitor 51 can be obtained.

As described above, according to the sixth embodiment, a part of the dielectric substrate 6 below the interdigital capacitor 51 is removed to form the recess 52 having no ground conductor 8. This has the effect of reducing the parasitic capacitance of the interdigital capacitor 51 and obtaining a larger coupling amount for the interdigital capacitor.

Embodiment 7 FIG. 9 is a plan view and a sectional view showing a configuration of an amplifier according to a seventh embodiment of the present invention. 9, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. Reference numeral 61 denotes a spiral inductor (inductor) formed on the dielectric substrate 6, and reference numeral 62 denotes a recess formed by removing a part of the dielectric substrate 6 so as to correspond to the spiral inductor 61.

A part of the dielectric substrate 6 below the spiral inductor 61 is removed to form a recess 62 having no ground conductor 8.
Is formed, the distance between the spiral inductor 61 and the ground conductor 8 can be increased. further,
Since the space below the spiral inductor 61 is filled with air having a relative dielectric constant lower than that of the dielectric substrate 6, the parasitic capacitance of the spiral inductor 61 is reduced.

As described above, according to the seventh embodiment, a part of the dielectric substrate 6 below the spiral inductor 61 is removed to form the recess 62 having no ground conductor 8. Since the parasitic capacitance related to the spiral inductor 61 can be reduced, a larger inductance can be obtained for the spiral inductor 61 and the self-resonant frequency can be increased.

Embodiment 8 FIG. FIG. 10 is a plan view and a sectional view showing a configuration of an MMIC amplifier according to an eighth embodiment of the present invention. 10, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. 71
Is a meander line (inductor) formed on the dielectric substrate 6, and 72 is a recess formed by removing a part of the dielectric substrate 6 so as to correspond to the meander line 71.

By removing a part of the dielectric substrate 6 below the meander line 71 to form a concave portion 72 having no ground conductor 8, the distance between the meander line 71 and the ground conductor 8 can be increased. it can. Further, the space below the meander line 71 is filled with air whose relative dielectric constant is lower than that of the dielectric substrate 6, so that the parasitic capacitance of the meander line 71 is reduced.

As described above, according to the eighth embodiment, a portion of the dielectric substrate 6 below the meander line 71 is removed to form the concave portion 72 having no ground conductor 8. Since the parasitic capacitance of the meander line 71 can be reduced, it is possible to obtain a larger inductance for the meander line 71 and to increase the self-resonant frequency.

The sixth and seventh embodiments described above.
Also, in the eighth embodiment, the concave portions 52, 62, and 72 can be configured to be filled with an insulating filler having a relative dielectric constant lower than that of the dielectric substrate 6, respectively. As in the fifth embodiment, there is an effect that it is possible to prevent solder or the like from entering into the concave portion and suppress fluctuations in the characteristic impedance.

[0045]

As described above, according to the present invention, the matching comprising the dielectric substrate, the amplifier formed on the dielectric substrate, and the input matching circuit and the output matching circuit formed on the dielectric substrate. A circuit and at least one formed by removing a part of the dielectric substrate under the entire region or the partial region of the matching circuit so as to reduce the thickness of the dielectric substrate under the entire region or the partial region of the matching circuit; And a ground conductor provided on the back side of the dielectric substrate at least in a region other than the region where the concave portion is formed. Since the width of the line that realizes the same impedance can be reduced and the isolation between lines can be increased, the circuit area can be reduced by high-density mounting. An effect that can mold of. In addition, in the case of the same circuit area, there is an effect that the degree of freedom of mounting can be increased by reducing the width of the line.

According to this invention, a part of the dielectric substrate below the stub is formed so as to selectively reduce the thickness of the dielectric substrate below the stub constituting the matching circuit. Since one or more concave portions having a ground conductor are provided in the portion, the line width of the microstrip line that realizes the same impedance for the stub can be reduced, and the degree of freedom related to the arrangement of the stub can be increased. In addition to this, there is an effect that the line width can be maintained large for other portions, and the loss can be suppressed.

According to the present invention, the lower dielectric substrate between the microstrip lines is partially removed so as to reduce the thickness of the dielectric substrate between the microstrip lines constituting the matching circuit. Since one or more concave portions having a ground conductor are provided on the outer surface, the electric field generated between the microstrip line and the ground conductor can be more efficiently confined to a narrow range. The effect that the coupling between lines can be reduced and the isolation between lines can be further improved can be achieved.

According to the present invention, the lower part of the dielectric material of the microstrip line constituting the matching circuit is reduced so that the thickness of the dielectric substrate below the part of the microstrip line is reduced. Since it was formed by removing a part of the substrate and provided with one or more concave portions having a ground conductor on the outer surface portion, the electrical width was increased in the same manner as the line width of the part of the microstrip line was increased. Since characteristics can be obtained, there is an effect that a filter circuit can be formed by using the electric characteristics.

According to the present invention, the matching circuit is formed by removing a part of the dielectric substrate under the capacitor so as to reduce the thickness of the dielectric substrate under the capacitor.
Since one or a plurality of recesses having no ground conductor are provided, the distance between the electrode constituting the capacitor and the ground conductor can be increased, and air having a lower relative dielectric constant than the dielectric substrate is provided in the recesses. Is satisfied, the parasitic capacitance of the capacitor can be reduced, and the MMI
There is an effect that the reliability of the circuit operation of C can be improved.

According to the present invention, since the capacitor is configured to be an interdigital capacitor, the distance between the electrode portion of the interdigital capacitor and the ground conductor is increased, so that the microstrip constituting the interdigital capacitor is formed. The electric field generated between the line and the ground conductor can be released to a wide range, and an effect that a larger coupling amount can be obtained for the interdigital capacitor can be obtained.

According to the present invention, the matching circuit is formed by removing a part of the dielectric substrate below the inductor so as to reduce the thickness of the dielectric substrate below the inductor,
Since one or more concave portions having no ground conductor are provided, the parasitic capacitance of the inductor can be reduced, so that a larger inductance can be obtained for the inductor and the self-resonant frequency can be increased. It has the effect of being able to.

According to the present invention, since the recess is filled with the insulating filler having a lower dielectric constant than the dielectric substrate, the penetration of the solder or the adhesive into the recess is prevented, and the characteristic impedance is reduced. The effect is obtained that the fluctuation can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view illustrating a configuration of an MMIC amplifier according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a substrate thickness of a dielectric substrate and a line width of a microstrip line formed on the substrate.

FIG. 3 is a plan view and a cross-sectional view illustrating a configuration of an MMIC amplifier according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration of a modification of the MMIC amplifier according to the second embodiment of the present invention;

FIGS. 5A and 5B are a plan view and a cross-sectional view illustrating a partial configuration of an MMIC amplifier according to a third embodiment of the present invention.

FIG. 6 is a plan view and a cross-sectional view showing a partial configuration of an MMIC amplifier according to a fourth embodiment of the present invention.

FIG. 7 is a plan view and a cross-sectional view showing a partial configuration of an MMIC amplifier according to a fifth embodiment of the present invention.

FIGS. 8A and 8B are a plan view and a cross-sectional view showing a partial configuration of an MMIC amplifier according to a sixth embodiment of the present invention.

FIG. 9 is a plan view and a cross-sectional view showing a partial configuration of an MMIC amplifier according to a seventh embodiment of the present invention.

FIG. 10 is a plan view and a cross-sectional view showing a partial configuration of an MMIC amplifier according to an eighth embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a configuration of a conventional MMIC.

FIG. 12 shows an MM identical to the MMIC shown in FIG.
FIG. 3 is a plan view showing an IC.

FIG. 13 is a cross-sectional view showing the configuration of another conventional MMIC.

[Explanation of symbols]

1 input terminal, 2 transistor, 3 output terminal, 4
Input matching stub, 5 Output matching stub, 5
_{1, 5 2} output matching stub () 6 dielectric _substrate, 7,7 _1, 7 2, 12,22,32,52,6
2,72 recess, 8 ground conductor, 11,21 microstrip line, 31 MIM capacitor (capacitor), 41 insulating filler, 51 interdigital capacitor (capacitor), 61 spiral inductor (inductor), 71 meander line (inductor) .

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Hiroaki Nakahan 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 5J067 AA01 AA04 CA00 CA92 FA16 HA09 HA29 HA33 KA29 KA66 KA68 KS11 LS12 QA04 QS02 QS04 TA02

Claims (8)

[Claims] 1. A matching circuit comprising a dielectric substrate, an amplifier formed on the dielectric substrate, an input matching circuit and an output matching circuit formed on the dielectric substrate, and an entire area of the matching circuit. Or one or more recesses formed by removing a part of the dielectric substrate below the entire region or the partial region of the matching circuit so as to reduce the thickness of the dielectric substrate below the partial region; A ground conductor provided on the back side of the dielectric substrate in a region other than the region where the concave portion is formed. 2. A grounding conductor is formed by removing a part of the dielectric substrate under the stub so as to selectively reduce the thickness of the dielectric substrate under the stub constituting the matching circuit. 2. The MMIC amplifier according to claim 1, further comprising one or more recesses having the following. 3. A part of a lower dielectric substrate between microstrip lines is formed so as to reduce a thickness of a lower dielectric substrate between microstrip lines constituting a matching circuit. The MMIC of claim 1, comprising one or more recesses having conductors.
amplifier. 4. A method for reducing the thickness of the dielectric substrate below a part of the microstrip lines so as to reduce the thickness of the dielectric substrate below the part of the microstrip lines constituting the matching circuit. 2. The MMIC amplifier according to claim 1, further comprising one or more concave portions formed by removing the portion and having a ground conductor on an outer surface portion. 5. One or a plurality of dielectric substrates formed under a capacitor by removing a part of the dielectric substrate under the capacitor so as to reduce the thickness of the dielectric substrate under the capacitor constituting the matching circuit. 2. The MMIC amplifier according to claim 1, further comprising a concave portion. 6. The MMIC amplifier according to claim 5, wherein the capacitor is an interdigital capacitor. 7. One or a plurality of dielectric substrates formed under a lower part of the inductor by removing a part of the dielectric substrate so as to reduce the thickness of the dielectric substrate under the inductor constituting the matching circuit, and having no ground conductor. 2. The MMIC amplifier according to claim 1, further comprising a concave portion. 8. The MMIC amplifier according to claim 5, wherein the recess is filled with an insulating filler having a dielectric constant lower than the dielectric constant of the dielectric substrate.