JP5448972B2 - High frequency amplifier circuit - Google Patents

Description

  The present invention relates to a high-frequency amplifier circuit used for wireless communication, an automotive radar device, and the like, and more particularly to a high-frequency amplifier circuit using a quasi-millimeter wave band of approximately 10 GHz or more and a high-frequency transistor used in the millimeter wave band.

  In a high-frequency amplifier circuit using a high-frequency transistor such as a field effect transistor (FET), a negative voltage is supplied to the gate terminal and a positive voltage is supplied to the drain terminal in order to stably operate the high-frequency transistor at a high frequency. A device configured to control a signal flowing through the drain is conventionally known. However, such a high-frequency amplifier circuit has problems such as high cost because it requires two types of power supplies.

  Thus, for example, Patent Documents 1 to 3 disclose high-frequency amplifier circuits that can be operated with only one power source. The high-frequency amplifier circuits described in Patent Documents 1 to 3 all employ a self-bias method. A configuration example of a conventional high-frequency amplifier circuit to which the self-bias method is applied is shown in FIG. FIG. 13 shows an equivalent circuit of the high-frequency amplifier circuit 900 configured as shown in FIG. As shown in FIGS. 12 and 13, the high-frequency amplifier circuit 900 has an input terminal 905 connected to the gate terminal 902 of the FET 901 and an output terminal 906 connected to the drain terminal 903 of the FET 901.

  One end of a resistor 907 whose other end is grounded is connected between the input terminal 905 and the gate terminal 902, and a DC signal on the gate terminal 902 side is short-circuited. A positive power supply 911 is connected between the output terminal 906 and the drain terminal 903 via a bias circuit 910 including an inductor 908 and a capacitor 909, and a positive bias voltage is applied to the drain terminal 903. . In the high frequency amplifier circuit 900 to which the self bias method is applied, the source terminal 904 of the FET 901 is grounded via the self bias circuit 912. The self-bias circuit 912 has a configuration in which a resistor 913 and a capacitor 914 are grounded in parallel.

In the high-frequency amplifier circuit 900 using the self-bias circuit 912, a voltage drop occurs due to the drain current Id flowing through the resistor 913. As a result, the gate-source voltage Vgs is given by the following formula: Vgs = −Rs × Id
Given in. Here, Rs is a resistance component of the resistor 913. As a result, the gate potential is apparently a negative potential. By using such a self-bias circuit 912, the high-frequency amplifier circuit 900 can be operated with only one power source.

  The resistor 913 and the capacitor 914 of the self-bias circuit 912 use the land 915 for connection to the source terminal 904 of the FET 901 and connect the ground side to the land 916. The land 916 is connected to a predetermined ground plane through a through hole 917.

JP 11-195936 A JP 2001-094361 A JP 09-181541 A

  However, there are parasitic capacitances in the resistors and capacitors used in the self-bias circuit, and there are inductor components in lands (signal lines) for surface mounting the resistors and capacitors. FIG. 14 shows an equivalent circuit in which parasitic capacitance and an inductor component are added to the equivalent circuit of the self-bias circuit 912 illustrated in FIG. As shown in the figure, the resistor 913 is a series circuit in which a resistance component Rs and an inductor component (Lr) are connected in series, and the capacitor 914 is a capacitor component (Cs) and an inductor component (Lc). Parallel circuits connected in parallel, lands 915 and 916 are, from a distributed constant circuit theory, a series circuit in which a resistance component (R) and an inductor component (L) are connected in series. Each can be represented equivalently.

  The equivalent circuit shown in FIG. 14 forms a resonance circuit. When the resonant circuit is formed in this way, reflection of high-frequency current or the like occurs and stable grounding becomes impossible, and the operation of the amplifier circuit becomes unstable. For this reason, the self-bias circuit has not been used in the conventional high frequency band of about 10 GHz or more. In the quasi-millimeter wave band to the millimeter wave band of approximately 10 GHz or more, in order to operate the amplifier circuit stably using high-frequency transistors, a positive power source is connected to the drain side and a negative power source is connected to the gate side at the same time. It is used as. The conventional high-frequency amplifier circuit has a problem that the source terminal of the amplifier circuit including the self-bias circuit using only the positive power source cannot be stably grounded.

  The present invention has been made to solve the above problems, and provides a high-frequency amplifier circuit that operates stably using a single power source in a quasi-millimeter wave band of approximately 10 GHz or more and in the millimeter wave band or more. Objective.

  According to a first aspect of the high frequency amplifier circuit of the present invention, a high frequency transistor having a gate terminal connected to an input terminal and a drain terminal connected to an output terminal and operating in a high frequency band of about 10 GHz or more, one end of the high frequency transistor is provided. A first resistor connected to the source terminal and grounded at the other end to make the DC potential of the gate terminal apparently lower than the ground potential, and one end connected to the source terminal and the other end grounded to short the high-frequency current For driving the high-frequency transistor connected to the drain side, a second resistor having one end connected to the gate terminal side and the other end grounded, and a self-bias circuit in which capacitors for paralleling are arranged in parallel A positive DC power source, and a bias circuit for preventing a high frequency signal output from the drain terminal from leaking to the DC power source. The first resistor and the capacitor are connected to a land formed on one surface of a predetermined substrate and connected to a ground formed on the other surface of the substrate through a through hole, and the first resistor and the The self-bias circuit including the distance D from the connection point between the capacitor and the land to the through hole is adjusted so that the stability factor K of the high-frequency amplifier circuit is 1 or more at a predetermined operating frequency. To do.

  Another aspect of the high-frequency amplifier circuit according to the present invention is characterized in that the distance D is determined by substituting the use frequency into a linear expression of a frequency created in advance.

  In another aspect of the high-frequency amplifier circuit of the present invention, the capacitor is disposed on one surface of the substrate so that another land of a predetermined size electrically connected to the land faces the ground. It is characterized by being formed.

  In another aspect of the high frequency amplifier circuit of the present invention, the capacitor is electrically connected to the land and arranged on one surface of the substrate with another land having a predetermined size and a through hole. A metal plate of a predetermined size connected to the ground and built in the substrate is formed so as to face each other with a predetermined distance therebetween.

  In another aspect of the high frequency amplifier circuit of the present invention, another land connected to the ground by a through hole is disposed on one surface of the substrate in the vicinity of the land, and the capacitor is disposed on a side surface of the land. And a side surface of the another land are separated from each other by a predetermined distance and face each other by a predetermined area.

  Another aspect of the high-frequency amplifier circuit of the present invention is characterized in that a dielectric having a predetermined dielectric constant is disposed between a side surface of the land and a side surface of the other land.

  According to the present invention, it is possible to provide a high-frequency amplifier circuit that operates stably using only a positive power supply in a quasi-millimeter wave band of approximately 10 GHz or more and in the millimeter wave band or more.

1 is a configuration diagram of a high-frequency amplifier circuit according to a first embodiment of the present invention. It is an equivalent circuit diagram of the high frequency amplifier circuit of the first embodiment. It is a graph which shows the relationship of the frequency versus the stability coefficient K when changing the distance D. It is a graph which shows the relationship of the frequency vs. stability coefficient K when distance D is made still longer. It is a graph which shows the relationship of distance D versus stability factor K at the frequency of 10 GHz. It is a graph which shows the relationship between the distance D with respect to the frequency of 10 GHz or more versus the stability coefficient K. It is a graph which shows the result of having compared the relation of frequency versus distance D with a primary approximation formula. It is a graph which shows the relationship of the distance D between different high frequency transistors. It is a perspective view which shows the structure of the high frequency amplifier circuit 200 of 2nd Embodiment. It is sectional drawing which shows the structure of the capacitor | condenser of another embodiment. It is sectional drawing which shows the structure of the capacitor | condenser of another embodiment. It is a block diagram of the conventional high frequency amplifier circuit which applied the self bias system. It is an equivalent circuit diagram of a conventional high-frequency amplifier circuit. It is the equivalent circuit diagram which added the parasitic capacitance and the inductor component to the conventional self-bias circuit.

  A configuration of a high-frequency amplifier circuit and a method for manufacturing the high-frequency amplifier circuit according to a preferred embodiment of the present invention will be described in detail below with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

(First embodiment)
A preferred first embodiment of a high-frequency amplifier circuit according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a high-frequency amplifier circuit according to this embodiment. The high-frequency amplifier circuit 100 shown in the figure is configured using a high-frequency transistor 101 that can be used in a high-frequency band of 10 GHz or higher.

  The high-frequency transistor 101 has a gate terminal 102, a drain terminal 103, and a source terminal 104. In FIG. 1, as an example, the high-frequency transistor 101 has two source terminals 104. The high-frequency transistor 101 is not limited to this, and may have only one source terminal 104 or a plurality having three or more. An input terminal 105 for inputting a high frequency signal (RF signal) of the input signal is connected to the gate terminal 102 side, and an output terminal 106 for outputting the signal amplified by the high frequency transistor 101 is connected to the drain terminal 103 side. ing.

  A resistor 111 and a capacitor 112 are connected to the two source terminals 104 via lands 107. The other ends of the resistor 111 and the capacitor 112 are grounded through lands 108a and 108b and through holes 109a and 109b, respectively. The resistor 111 and the capacitor 112 form a self-bias circuit 110.

  The configuration of the high-frequency amplifier circuit 100 will be described in more detail using the equivalent circuit of the high-frequency amplifier circuit 100 shown in FIG. FIG. 2 shows an equivalent circuit of the high-frequency amplifier circuit 100 shown in FIG. In the high frequency amplifier circuit 100 of the present embodiment, a resistor 113 is connected between the input terminal 105 and the gate terminal 102, and the other end of the resistor 113 is grounded via the land 114 and the through hole 115.

  A positive DC power supply 116 is connected between the output terminal 106 and the drain terminal 103 via a bias circuit 117. The positive DC power supply 116 supplies a positive DC voltage for driving to the drain terminal 103 side. The bias circuit 117 is configured by a parallel circuit of an inductor 118 and a capacitor 119 so that a high frequency signal does not leak to the power supply 116 side. A matching circuit (not shown) for impedance matching is connected to each of the gate terminal 102 side, the drain terminal 103 side, and the source terminal 104 side of the high-frequency transistor 101.

  By connecting the self-bias circuit 110 to the source terminal 104 side, the high-frequency transistor 101 can be operated as an amplifier circuit without connecting a bias power source to the gate terminal 102 side. That is, with the circuit configuration as shown in the equivalent circuit of FIG. 2, a drain current Id flows between the drain terminal 103 and the source terminal 104, and a voltage drop occurs due to the drain current flowing through the resistor 111. As a result, the potential of the gate terminal 102 apparently becomes lower than the ground potential 0V. Further, the high-frequency signal can be short-circuited by connecting the capacitor 112 whose other end is grounded in parallel.

  In the high-frequency amplifier circuit 100 configured as described above, a chip resistor and a chip capacitor are used as the resistor 111 and the capacitor 112 constituting the self-bias circuit 110, respectively. Therefore, the resistor 111 and the capacitor 112 have parasitic capacitance. The lands 107 and 108 (108a and 108b) on which the resistor 111 and the capacitor 112 are surface-mounted have an inductor component. In the equivalent circuit of the high-frequency amplifier circuit 100 shown in FIG. 2, the inductor components are indicated by inductors 121 to 123. The lands 107 and 108 are collectively represented by an equivalent circuit in which a resistor 124 and an inductor 123 are connected in series.

  When inductor components 121 to 123 as shown in the equivalent circuit of FIG. 2 are generated, the self-bias circuit 110 becomes a resonance circuit. As a result, for a high frequency of about 10 GHz or more, the high frequency signal is reflected without being short-circuited from the capacitor 112, and the amplifier circuit does not operate stably at the operating frequency.

  Therefore, in the high-frequency amplifier circuit 100 of the present embodiment, the above-described inductor component is applied to the self-bias circuit 110 formed in the above-described resonant circuit so that the resonance point is a stable region of the high-frequency amplifier circuit 100. adjust. Among the inductor components 121 to 123, the sizes of the inductor components 121 and 122 included in the resistor 111 and the capacitor 112 cannot be easily adjusted. Therefore, in the present embodiment, the inductor component 123 included in the lands 107 and 108 is adjusted.

  In this embodiment, in order to adjust the inductor component 123, a distance D (hereinafter referred to as self-bias) from a connection point between the resistor 111 and the capacitor 112 on the land 108 shown in FIG. 1 to the through hole 109 (109a, 109b). The distance D to the through hole 109 of the circuit 110 is adjusted. When the distance D is changed, the inductor component 123 changes. Therefore, by adjusting the inductor component 123 by changing the distance D, the resonance point of the self-bias circuit 110 becomes a stable region of the high-frequency amplifier circuit 100.

上式において、Ｓ１１、Ｓ１２、Ｓ２１、Ｓ２２は、Ｓパラメータである。Ｓ１１、Ｓ２２は、それぞれ入力端子側、出力端子側から見た反射係数を表し、Ｓ１２、Ｓ２１は、それぞれ出力側から入力側への逆方向の通過係数、及び入力側から出力側への順方向の通過係数を表している。 The knurled stability coefficient K can be used to determine whether the high-frequency amplifier circuit 100 is stable in the used frequency band. It is known that the knurled stability coefficient K decreases when unstable at a predetermined frequency. The knurled stability coefficient K is defined as:

In the above equation, S11, S12, S21, and S22 are S parameters. S11 and S22 represent reflection coefficients as viewed from the input terminal side and the output terminal side, respectively. S12 and S21 respectively represent a passage coefficient in the reverse direction from the output side to the input side, and the forward direction from the input side to the output side. Represents the pass coefficient.

  When the knurled stability coefficient K is used, an unconditional stable region when the value of K in the above expression is 1 or more (K ≧ 1), and a conditional stable region when greater than 0 and less than 1 (0 <K <1) When 0 or less (K ≦ 0), the region becomes unstable. When the inductor component 123 is generated in the resistor 111 and the capacitor 112 of the self-bias circuit 110 and the lands 107 and 108, a resonance circuit is generated, and the reflection coefficient S11 on the input side and the reflection coefficient S22 on the output side are increased. As a result, the value of K changes to the negative side from Equation (1).

  Therefore, in the method of manufacturing the high frequency amplifier circuit according to the present embodiment, the distance D to the through hole 109 of the self-bias circuit 110 is changed so that the stability coefficient K of the equation (1) is 1 or more. Adjust the value. Specifically, when the distance D is a predetermined value, the S parameter at that time can be obtained by measuring a traveling wave and a reflected wave of a predetermined high-frequency signal. From the obtained S parameter, the stability coefficient K is calculated using Equation (1). Similarly, the distance D is changed until the stability coefficient K becomes 1 or more.

  As an example, FIG. 3 shows a change in the stability coefficient K when the distance D is gradually increased from 0.35 mm which is the minimum value in manufacturing. In FIG. 3, the horizontal axis represents the frequency f [GHz] of the high-frequency signal input to the high-frequency amplifier circuit 100, and the vertical axis represents the stability coefficient K on a logarithmic scale. Further, changes in the stability coefficient K when D = 0.35, 1.35, 3.85, 4.855.6.85 mm are indicated by reference numerals 11 to 15, respectively. In the figure, the high frequency amplifier circuit 100 is in the unconditional stable region when K ≧ 1 above the line K = 1 (indicated by reference numeral 10). From the figure, it can be seen that when the distance D = 6.85 mm (reference numeral 15), K ≧ 1 with respect to a high-frequency signal having a frequency of approximately 10 GHz or more, and the operation is stable.

  FIG. 4 shows an example of a change in the stability coefficient K when the distance D is further increased from 6.85 mm to 9.85 mm. Here, changes of the stability coefficient K when D = 7.85, 8.85, and 9.85 mm are indicated by reference numerals 16 to 18. As shown in the figure, when the length is further increased beyond 6.85 mm, the stability coefficient K again enters the unstable region in the vicinity of about 10 GHz. FIG. 5 shows a graph showing the change of the stability coefficient K with respect to the distance D for a high-frequency signal having a frequency of 10 GHz based on such a result. From the figure, the range of the distance D where the stability coefficient K ≧ 1 is 4 mm <D <8 mm for a high-frequency signal having a frequency of 10 GHz. The distance D having the largest stability coefficient K and high stability is about 7 mm.

  Next, a graph showing the change of the stability coefficient K with respect to the distance D for different frequencies of 10 GHz or more is shown in FIG. In the figure, the change of the stability coefficient K when the matching circuit is adjusted and the frequency is changed by 1 GHz from 10 GHz to 16 GHz is indicated by reference numerals 20 to 26. From the figure, it can be seen that the distance D when the stability coefficient K enters the stable region decreases as the frequency increases.

  For a high-frequency amplifier circuit using two types of high-frequency transistors (TR1 and TR2) of different manufacturers, the relationship between the distance D for each frequency and the stability coefficient K as shown in FIG. 6 is obtained. FIG. 7 shows the result of comparison of the relationship between the frequency and the distance D when the stability coefficient K enters the stable region. Here, reference numerals 31 and 32 indicate the results when the high-frequency transistors TR1 and TR2 are used, respectively. FIG. 7 shows that there is a substantially linear relationship between the frequency and the distance D. In the figure, reference numeral 30 indicates a result obtained by approximating a linear relationship between the frequency of the high-frequency transistor TR1 and the distance D by a linear expression. By approximating the linear relationship of frequency vs. distance D with a linear expression, a suitable distance D can be uniquely determined from the linear expression based on the frequency of the high-frequency signal.

Further, FIG. 8 shows the result of obtaining the correlation between the relationship between the frequency vs. distance D of the high frequency transistor TR1 and the relationship between the frequency vs. distance D of the high frequency transistor TR2 of another manufacturer. The correlation coefficient (R ² ) between the high-frequency transistors TR1 and TR2 is about 98%, which indicates that the characteristics are almost the same regardless of the manufacturer. Therefore, regardless of the type of high-frequency transistor or the manufacturer, the relationship between the frequency of the high-frequency signal and the distance D can be approximated by a linear expression. Can be determined uniquely.

  By using the high-frequency amplifier circuit of the present embodiment described above, the source side can be stably grounded using a self-bias circuit in a quasi-millimeter wave band and a millimeter wave band of 10 GHz or more. It is possible to provide a stable high-frequency amplifier circuit. Since it is possible to use the self-bias method for a high-frequency band of 10 GHz or higher, a high-frequency amplifier circuit that can operate with only one power source can be realized, and the high-frequency circuit can be reduced in size, saved in energy, and reduced in cost. realizable. Further, a self-bias circuit can be configured by a resonance circuit using the inductor component of the source terminal regardless of the type of the high-frequency transistor.

  A high-frequency amplifier circuit according to another embodiment of the present invention will be described below with reference to FIG. FIG. 9 is a perspective view showing the configuration of the high-frequency amplifier circuit 200 of the present embodiment. The figure shows a state where the high frequency amplifier circuit 200 is mounted on a predetermined substrate 202. The substrate 202 is a substrate mounted on, for example, a mobile phone.

Conventionally, a resistor that can be surface-mounted and a capacitor that can be surface-mounted have been used as the resistor and the capacitor constituting the self-bias circuit. Therefore, a resonance circuit is formed by each parasitic capacitance, and there is a problem that high-frequency signals are reflected and cannot be stably grounded. Therefore, in this embodiment, the self-bias circuit is configured without using a surface-mountable capacitor. Thereby, the influence of parasitic capacitance can be reduced.

  In this embodiment, the surface mount capacitor 112 shown in FIG. 1 used in the first embodiment is not used, and a capacitor is directly formed using a predetermined substrate. In FIG. 9, a capacitor 212 a corresponding to the capacitor 112 of the first embodiment is formed using a substrate 202, and a self-bias circuit 210 is formed by this and a resistor 111. The capacitor 212a has a land 213 having a predetermined size on the substrate 202, and is statically placed between the land 213 and a ground 203 (not shown) formed on the back surface of the substrate 202 with the substrate 202, air, or the like interposed therebetween. It is formed to have electric capacity. As the land 213, for example, the land 107 can be used.

  Since the capacitor 212 a formed in this way has a very small parasitic capacitance, the self-bias circuit 210 is only affected by the parasitic capacitance of the resistor 111. As a result, since the influence of the parasitic capacitance can be greatly reduced, the high-frequency amplifier circuit 100 having the self-bias circuit 210 using the resonance circuit can be easily and stably grounded in a high-frequency band of approximately 10 GHz or more. It can be operated.

  Another embodiment of the capacitor used in the self-bias circuit 210 will be described with reference to FIG. FIG. 10 is a cross-sectional view showing the structure of a capacitor according to another embodiment. The capacitor 212b shown in the figure has another metal plate 214 built in the substrate 202. The metal plate 214 is connected to the ground 203 through the through hole 215, and is formed so as to have a capacitance between the land 213 and the metal plate 214.

で与えられる。ここで、εｒは基板２０２の比誘電率、Ｓは金属板２１４の面積（ランド２１３より小さいとしている）、ｄはランド２１３と金属板２１４との距離、を表している。金属板２１４を用いた場合には、式（２）に示すように、金属板２１４の寸法や内蔵位置を変更することで、寄生容量を非常に小さくしながらコンデンサ２１２ｂの容量Ｃを容易に設定することができる。 The capacitance C of the capacitor 212b is given by

Given in. Here, εr represents the relative dielectric constant of the substrate 202, S represents the area of the metal plate 214 (which is smaller than the land 213), and d represents the distance between the land 213 and the metal plate 214. When the metal plate 214 is used, the capacitance C of the capacitor 212b can be easily set while changing the dimensions and the built-in position of the metal plate 214 as shown in the equation (2) while making the parasitic capacitance very small. can do.

  Still another embodiment of the capacitor used in the self-bias circuit 210 will be described with reference to FIG. FIG. 11 is a cross-sectional view showing the structure of a capacitor according to still another embodiment. The capacitor 212c shown in the figure is formed by disposing another land 216 in the vicinity of the land 107. The land 216 is connected to the ground 203 through a through hole 217. By setting the area of the opposing side surfaces of the lands 107 and 216 and the distance between them, the capacitance of the capacitor 212c can be set while making the parasitic capacitance very small. Capacitance can be increased by flowing a predetermined dielectric 218 between the opposing side surfaces of the lands 107 and 216.

  The parasitic capacitance of the self-bias circuit 210 can be reduced by using any of the capacitors 212a, 212b, and 212c of the above embodiment. As a result, since the influence of the parasitic capacitance can be greatly reduced, the high frequency signal can be stably grounded. On the other hand, the direct current does not pass even if any of the capacitors 212a, 212b, and 212c of the above embodiment is used, and the resistor 111 can make the apparent direct current potential of the gate appear lower than the ground potential.

  Note that the description in the present embodiment shows an example of the high-frequency amplifier circuit according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the high-frequency amplifier circuit in this embodiment can be changed as appropriate without departing from the spirit of the present invention.

100, 200 High-frequency amplifier circuit 101 High-frequency transistor 102 Gate terminal 103 Drain terminal 104 Source terminal 105 Input terminal 106 Output terminal 107, 108a, 108b, 114, 213, 216 Land 109a, 109b, 115, 217 Through-hole 110, 210 Self-bias Circuit 111, 113, 124 Resistor 112, 119, 212a, 212b Capacitor 116 Power supply 117 Bias circuit 118, 121-123 Inductor 202 Substrate 203 Ground 214 Metal plate 215 Through hole 218 Dielectric

Claims (6)

A high frequency transistor operating in a high frequency band with a gate terminal connected to an input terminal and a drain terminal connected to an output terminal;
One end is connected to the source terminal of the high-frequency transistor and the other end is grounded so that the DC potential of the gate terminal is apparently lower than the ground potential, and one end is connected to the source terminal and the other end is grounded A self-bias circuit in which capacitors for short-circuiting the high-frequency current are arranged in parallel;
A second resistor having one end connected to the gate terminal side and the other end grounded;
A positive DC power source connected to the drain side for driving the high-frequency transistor;
A bias circuit for preventing a high-frequency signal output from the drain terminal from leaking to the DC power supply ;
And a land connected by through holes to a predetermined formed on one surface of the substrate ground formed on the other surface of the substrate,
The first resistor and the capacitor are directly connected to the land and grounded,
The first resistor and the capacitor are connected from the connection point with the land to the through hole so that the high-frequency transistor operates only with the DC power source and the stability coefficient K is 1 or more at a predetermined use frequency . A high-frequency amplifier circuit which is connected to the land by adjusting a distance D. The high-frequency amplifier circuit according to claim 1, wherein the distance D is determined by substituting the used frequency into a linear expression of a frequency created in advance. The capacitor is formed by disposing another land of a predetermined size electrically connected to the land on one surface of the substrate so as to face the ground. Item 3. The high frequency amplifier circuit according to Item 1 or 2. The capacitor is electrically connected to the land and another land of a predetermined size disposed on one surface of the substrate, and a predetermined capacitor that is connected to the ground via a through hole and is embedded in the substrate. 4. The high-frequency amplifier circuit according to claim 1, wherein the high-frequency amplifier circuits are formed so as to face each other with a predetermined distance from each other. Another land connected to the ground by a through hole is disposed on one surface of the substrate in the vicinity of the land, and the capacitor has a predetermined distance between a side surface of the land and a side surface of the other land. 4. The high-frequency amplifier circuit according to claim 1, wherein the high-frequency amplifier circuit is formed so as to be opposed to each other by a predetermined area. 6. The high frequency amplifier circuit according to claim 5, wherein a dielectric having a predetermined dielectric constant is disposed between a side surface of the land and a side surface of the other land.

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