High-frequency circuit

Abstract

To stabilize and suppress the deterioration in characteristic.SOLUTION: A high frequency circuit includes a transistor including an input electrode to which a high frequency signal is input and an output electrode from which the high frequency signal is output, a transmission line 18 connected to one of the input electrode and the output electrode and transmitting the high frequency signal, a coupling line 16 provided in an electrically separated manner from the transmission line to such a degree that electromagnetic field coupling with the transmission line is possible, and a resonance circuit 12 that is connected between a first end of the coupling line and a reference potential and minimizes the impedance between the first end and the reference potential at the resonance frequency.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a high-frequency circuit.

Background Art

[0002] It is known to connect the first end of an open stub to the main line through which a high-frequency signal is transmitted in a high-frequency circuit, bring a transmission line close to the open stub, and ground both ends of the transmission line through resistors. Ru( For example, Patent Document 1). It is known to provide a parallel resonance circuit in a bias circuit that supplies a bias voltage to a transistor (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Documents 1 and 2, the high-frequency circuit can be stabilized. However, when a stabilization circuit for stabilizing the high-frequency circuit is directly connected to the line through which the high-frequency signal is transmitted, it affects the characteristics of the high-frequency circuit and the characteristics deteriorate.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to stabilize and suppress characteristic deterioration.

Means for Solving the Problems

[0006] One embodiment of the present disclosure is a high-frequency circuit including a transistor having an input electrode to which a high-frequency signal is input and an output electrode from which a high-frequency signal is output, a transmission line connected to one of the input electrode and the output electrode through which the high-frequency signal is transmitted, a coupling line provided electrically separated from the transmission line to such an extent that electromagnetic field coupling is possible, and a resonance circuit connected between a first end of the coupling line and a reference potential and minimizing the impedance between the first end and the reference potential at a resonance frequency.

Advantages of the Invention

[0007] According to the present disclosure, stabilization and suppression of characteristic degradation can be achieved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0009] [Description of Embodiments of the Present Disclosure] First, the content of the embodiment of the present disclosure will be listed and described. (1) One embodiment of the present disclosure includes a transistor having an input electrode to which a high-frequency signal is input and an output electrode from which a high-frequency signal is output, a transmission line connected to either one of the input electrode and the output electrode through which the high-frequency signal is transmitted, a coupling line provided electrically separated from the transmission line to such an extent that electromagnetic field coupling is possible, and a resonance circuit connected between a first end of the coupling line and a reference potential and minimizing the impedance between the first end and the reference potential at a resonance frequency. By connecting the resonance circuit to the coupling line, stabilization and suppression of characteristic degradation can be achieved. (2) A resistance element is provided, a first end of the resistance element is connected to a second end of the coupling line, a second end of the resistance element is connected to the reference potential, and it is preferable that a resistance value of the resistance element is equal to or greater than 1 / 2 times and equal to or less than 2 times a characteristic impedance of the coupling line at a center frequency of an operating frequency band of the high-frequency circuit. (3) It is preferable to include an input terminal to which a high-frequency signal is input and a matching circuit that matches an input impedance of the input terminal and an input impedance of the input electrode, wherein a first end of the transmission line is connected to the matching circuit and a second end is connected to the input electrode. (4) It is preferable to include an output terminal from which a high-frequency signal is output and a matching circuit that matches an output impedance of the output electrode and an output impedance of the output terminal, wherein a first end of the transmission line is connected to the output electrode and a second end is connected to the output terminal. (5) It is preferable that the input electrode is a gate and the output electrode is a drain. (6) It is preferable that a stability factor of the high-frequency circuit when the coupling line and the resonance circuit are not provided is less than 1 at a resonance frequency of the resonance circuit. (7) It is preferable that the resonance frequency of the resonance circuit is lower than an operating frequency band of the high-frequency circuit. (8) It is preferable that the resonance circuit includes an inductor and a capacitor connected in series between a first end of the coupling line and the reference potential.

[0010] [Details of Embodiments of the Present Disclosure] A specific example of a high-frequency circuit according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0011] [Example 1] In Example 1, a high-frequency power amplifier used in a base station for mobile communication as a high-frequency circuit will be described as an example. FIG. 1 is a circuit diagram of the high-frequency circuit according to Example 1. As shown in FIG. 1, the high-frequency circuit 100 includes a stabilization circuit 10, an amplifier 20, matching circuits 26 and 28. The amplifier 20 includes a transistor 21. The transistor 21 is an FET (Field Effect Transistor) such as a GaN HEMT (Gallium Nitride High Electron Mobility Transistor), for example. The center frequency of the band of the high-frequency circuit 100 is, for example, 0.5 GHz to 10 GHz.

[0012] The input terminal Tin is connected to the gate G of the transistor 21 via the matching circuit 26, and the drain D of the transistor 21 is connected to the output terminal Tout via the matching circuit 28. The source S of the transistor 21 is connected to the ground potential (reference potential). The transistor 21 amplifies the high-frequency signal 50 input to the input terminal Tin and outputs it to the output terminal Tout. The frequency f1 of the high-frequency signal 50 amplified by the amplifier 20 is, for example, the center frequency of the operating band of the high-frequency circuit 100. The matching circuit 26 is a circuit that matches the input impedance seen from the input terminal Tin from an external circuit at the frequency f1 with the input impedance of the amplifier 20 seen from the gate G from the matching circuit 26. The matching circuit 28 is a circuit that matches the output impedance of the amplifier 20 seen from the drain D at the frequency f1 with the output impedance seen from the output terminal Tout to an external circuit. A transmission line 18 is provided between the matching circuit 26 and the gate G.

[0013] The stabilization circuit 10 includes a resonance circuit 12, a resistance element 14, and a coupling line 16. The coupling line 16 extends in the extending direction of the transmission line 18, and the transmission line 18 is provided at a certain distance from the coupling line 16. The coupling line 16 is electromagnetically coupled to the transmission line 18. The 2 end of the coupling line 16 is connected to the reference potential via the resistance element 14. The resistance value of the resistance element 14 is the characteristic impedance of the coupling line 16 at the frequency f1. The 1 end of the coupling line 16 is connected to the reference potential via the resonance circuit 12. The resonance circuit 12 is a series resonance circuit including an inductor L1 and a capacitor C1. At the resonance frequency fr of the resonance circuit 12, the impedance between the coupling line 16 and the reference potential becomes extremely small. The resonance frequency fr is, for example, the frequency at which the high-frequency circuit 100 is likely to oscillate (i.e., the high-frequency circuit 100 is likely to become unstable) when the stabilization circuit 10 is not provided.

[0014] The stability coefficient K of the high-frequency circuit 100 is given by the following mathematical formula 1.

Equation

[0015] When the stability coefficient K is 1 or less, the high-frequency circuit 100 becomes unstable and is prone to oscillation. The high-frequency circuit is designed using matching circuits 26 and 28 such that the stability coefficient K is greater than 1 in the operating band of the high-frequency circuit 100. However, when the high-frequency circuit 100 operates, the high-frequency circuit 100 also performs a non-linear operation. For this reason, signals of frequencies outside the operating frequency band in which the high-frequency circuit 100 operates are generated inside the high-frequency circuit 100. And when the stability coefficient K becomes 1 or less at frequencies outside the band in which the high-frequency circuit 100 operates, the high-frequency circuit 100 becomes prone to oscillation. Since the high-frequency signal 52 having a frequency f2 near the resonance frequency fr flows from the transmission line 18 to the ground via the coupling line 16, the S21 of the high-frequency circuit 100 at the frequency f2 decreases. From Equation 1, when the S21 of the high-frequency circuit 100 decreases, the stability coefficient K increases. Therefore, the stability coefficient K near the frequency f2 can be increased. Since the impedance of the resonance circuit 12 is large at the frequency f1, the high-frequency signal 50 does not pass through the resonance circuit 12. The second end of the coupling line 16 is terminated by the resistance element 14. For this reason, the isolation between the transmission line 18 and the coupling line 16 increases at the frequency f1. Therefore, at the frequency f1, the stabilization circuit 10 hardly affects the transmission line 18, and the gain of the high-frequency circuit 100 at the frequency f1 hardly changes with the presence or absence of the stabilization circuit 10. The resistance value of the resistance element 14 is the characteristic impedance of the coupling line 16 and is, for example, 50 Ω.

[0016] [Stabilization Circuit] FIG. 2 is a plan view of the stabilization circuit 10 in the first embodiment. FIGS. 3 and 4 are a cross-sectional view taken along line A-A and a cross-sectional view taken along line B-B of FIG. 2, respectively. As shown in FIGS. 2 to 4, a metal layer 32 is provided on the upper surface of the dielectric substrate 30, and a metal layer 34 is provided on the lower surface. The dielectric substrate 30 is a dielectric substrate such as a resin such as FR-4 (Flame Retardant Type 4) or a ceramic. The metal layers 32 and 34 are, for example, a copper layer or a gold layer. The metal layer 34 is provided over the entire lower surface of the dielectric substrate 30, and a reference potential such as a ground potential is supplied. The metal layer 32 forms patterns 32a to 32g.

[0017] Pattern 32a is the signal line of transmission line 18. A microstrip line is formed by pattern 32a and metal layer 32. Pattern 32b is the signal line of coupling line 16. Patterns 32a and 32b are substantially parallel. A microstrip line is formed by pattern 32b and metal layer 32. The widths of patterns 32a and 32b are W1 and W2, respectively. The distance between patterns 32a and 32b is W3. The length of pattern 32b is L1. The thickness of dielectric substrate 30 is T1. The widths W1, W2, and thickness T1 are designed such that the characteristic impedances of transmission line 18 and coupling line 16 become desired values at frequency f1. The distance W3 and length L1 are set such that the coupling amount between transmission line 18 and coupling line 16 becomes a desired value that does not affect the insertion loss of transmission line 18.

[0018] Pattern 32c is connected to the first end of pattern 32b. Pattern 32d is provided away from pattern 32c, and pattern 32e is provided away from pattern 32d. Both ends of electronic component 38a are joined onto patterns 32c and 32d respectively using bonding material 35. Both ends of electronic component 38b are joined onto patterns 32d and 32e respectively using bonding material 35. Pattern 32e is electrically connected and short-circuited to metal layer 34 by via electrode 36 that penetrates dielectric substrate 30. Electronic component 38a is a coil component and corresponds to inductor L1. Electronic component 38b is a capacitor component and corresponds to capacitor C1. Resonant circuit 12 is formed by electronic components 38a and 38b.

[0019] Pattern 32f is connected to the second end of pattern 32b. Pattern 32g is provided away from pattern 32f. Both ends of electronic component 38c are joined onto patterns 32f and 32g respectively using bonding material 35. Pattern 32g is electrically connected and short-circuited to metal layer 34 by via electrode 36 that penetrates dielectric substrate 30. Electronic component 38c is a resistor component and corresponds to resistor R1.

[0020] Although an example has been described in which electronic components 38a to 38c are used as the inductor L1, the capacitor C1, and the resistor R1, the inductor L1 may be a circuit pattern formed by the metal layer 32. The capacitor C1 may be a MIM (Metal Insulator Metal) capacitor provided on the dielectric substrate 30. The resistor R1 may be a resistor thin film provided on the dielectric substrate 30.

[0021] [Comparative Example] FIG. 5 is a circuit diagram of a high-frequency circuit according to Comparative Example 1. As shown in FIG. 5, in the high-frequency circuit 110 in Comparative Example 1, a resonance circuit 12 is shunt-connected to the transmission line between the matching circuit 26 and the gate G. In Comparative Example 1, similar to Example 1, by setting the resonance frequency fr of the resonance circuit 12 to be near the frequency f2 of the high-frequency signal 52, the stability factor K of the high-frequency circuit 110 at the frequency f2 can be increased. On the other hand, the band of the high-frequency circuit 110 is different from the resonance frequency of the resonance circuit 12. Therefore, the impedance of the resonance circuit 12 becomes high near the frequency f1 of the high-frequency signal 50. Thus, a decrease in the gain of the high-frequency circuit 110 at the frequency f1 is suppressed.

[0022] However, although the impedance of the resonance circuit 12 is high at the frequency f1, it is not infinite. Therefore, a part of the high-frequency signal 50 leaks to the reference potential through the resonance circuit 12. As a result, the loss at the frequency f1 increases. Also, the inductor L1 and the capacitor C1 of the resonance circuit 12 affect the transmission line 18. For example, the resonance circuit 12 affects the impedance matching between the input terminal Tin and the gate G. Thereby, the impedance matching by the matching circuit 26 changes from the optimal state, and the high-frequency characteristics of the high-frequency circuit 110 deteriorate.

[0023] As Comparative Example 2 referring to Patent Document 1, it is also conceivable to connect an open stub having a length of λ / 4 to the transmission line 18 and couple a coupling line to the open stub. Here, λ is the wavelength at the frequency at which it is desired to increase the stability factor K. However, since a λ / 4 open stub is used, the circuit area becomes large. Since the open stub is connected to the transmission line 18, the open stub affects impedance matching.

[0024] According to Example 1, as shown in FIG. 1, the transmission line 18 through which the high-frequency signal 50 is transmitted is connected to the gate G (input electrode to which the high-frequency signal is input) of the transistor 21. The coupling line 16 is provided electrically separated from the transmission line 18 to such an extent that electromagnetic coupling with the transmission line 18 through which the high-frequency signal 50 is transmitted is possible. As a result, a part of the high-frequency signal transmitted through the transmission line 18 branches off to the coupling line 16. The resonance circuit 12 is connected between the first end of the coupling line 16 and the ground (reference potential), and minimizes the impedance between the first end and the ground at the resonance frequency fr. As a result, the high-frequency signal 52 having the frequency f2 among the high-frequency signals branched off to the coupling line 16 flows to the ground through the resonance circuit 12. Therefore, at the frequency f2, it is possible to stabilize the high-frequency circuit 110.

[0025] The first end of the resistance element 14 is connected to the second end of the coupling line 16, and the second end is connected to the ground. The resistance value of the resistance element 14 is the characteristic impedance of the coupling line 16 at the center frequency f1 of the operating frequency band of the high-frequency circuit 100. Thereby, the isolation at the frequency f1 between the transmission line 18 and the coupling line 16 can be increased. Therefore, it is possible to suppress the leakage of the high-frequency signal 50 having the frequency f1 into the stabilization circuit 10 and suppress the decrease in gain at the frequency f1. Since the second end of the coupling line 16 is terminated using the resistance element 14, the resistance value of the resistance element 14 is preferably 1 / 2 times or more and 2 times or less, more preferably 2 / 3 times or more and 1.5 times or less, and even more preferably 3 / 4 times or more and 1.3 times or less of the characteristic impedance of the coupling line 16 at the frequency f1.

[0026] The first end of the transmission line 18 is connected to a matching circuit 26 that matches the input impedance of the input terminal Tin and the input impedance of the gate G, and the second end is connected to the gate G of the transistor. When the stabilization circuit 10 is provided between the matching circuit 26 and the transistor 21, if the resonance circuit 12 is directly connected to the transmission line 18 as in Comparative Example 1, resonant circuit 12 the impedance matching will deviate from the optimum value due to this. Therefore, as in the first embodiment, it is preferable to provide the coupling line 16.

[0027] The resonance circuit 12 includes an inductor L1 and a capacitor C1 connected in series between the first end of the coupling line 16 and the ground. Thereby, the resonance circuit 12 becomes short at the resonance frequency fr, and the high-frequency signal 52 having a frequency f2 near the resonance frequency fr can be passed to the ground, increasing the stability factor K at the frequency f2. The connection order of the inductor L1 and the capacitor C1 may be reversed from that of the first embodiment.

[0028] [Modification Example 1 of the First Embodiment] FIG. 6 is a circuit diagram of a high-frequency circuit according to Modification Example 1 of the first embodiment. As shown in FIG. 6, in the high-frequency circuit 102 of Modification Example 1 of the first embodiment, the first end of the transmission line 18 is connected to the drain D of the transistor 21, and the second end is connected to the matching circuit 28. Other configurations are the same as those of the first embodiment and the description thereof is omitted. As in Modification Example 1 of the first embodiment, the transmission line 18 is connected to the drain D (output electrode from which the high-frequency signal is output) of the transistor 21. The first end of the transmission line 18 may be connected to the drain D (output electrode) of the transistor 21, and the second end may be connected to a matching circuit 28 that matches the output impedance of the drain D and the output impedance of the output terminal Tout.

[0029] When the transistor 21 is an amplifier 20, a high-frequency signal with a large amount of power is output to the drain D. For this reason, in Modification 1 of Example 1, each electronic component (electronic components 38a to 38c in FIGS. 2 to 4) in the stabilization circuit 10 becomes a high-voltage-resistant and expensive component. Therefore, it is preferable that the stabilization circuit 10 is provided between the matching circuit 26 and the gate G as in Example 1. When the transistor 21 functions as a multiplier or a mixer, as in Modification 1 of Example 1, the stabilization circuit 10 may be provided between the drain D and the matching circuit 28.

[0030] [Example 2] Example 2 is a specific example of Example 1. FIG. 7 is a circuit diagram of a high-frequency circuit according to Example 2. As shown in FIG. 7, in the high-frequency circuit 104, a transmission line S3, a capacitor C7, a transmission line S4, and a CR filter 27 are connected between the input terminal Tin and the matching circuit 26. A bias circuit 22 is connected between the transmission line 18 and the amplifier 20. A bias circuit 24 is connected between the amplifier 20 and the matching circuit 28. A transmission line S5, a capacitor C8, and a transmission line S6 are connected between the matching circuit 28 and the output terminal Tout. The transmission lines S3 to S6 are lines through which high-frequency signals propagate. The capacitors C7 and C8 are DC cut capacitors that allow high-frequency signals to pass through and cut DC (Direct Current) components.

[0031] The CR filter 27 includes a capacitor C6 and a resistor R2 connected in parallel. The CR filter 27 is a high-pass filter that allows high-frequency signals in the band amplified by the amplifier 20 to pass through and suppresses signals with low frequencies and a low stability coefficient K. The bias circuit 22 includes a transmission line S1 and a capacitor C4. The transmission line S1 is connected between the gate G of the transistor 21 and the bias terminal 23 and has a length of, for example, λ / 4. The capacitor C4 is connected between the bias terminal 23 and the ground. The bias circuit 22 supplies the gate bias voltage Vg supplied to the bias terminal 23 to the gate G and suppresses the passage of high-frequency signals through the bias terminal 23.

[0032] The bias circuit 24 includes a transmission line S2 and a capacitor C5. The transmission line S2 is connected between the drain D of the transistor 21 and the bias terminal 25, and has a length of, for example, λ / 4. The capacitor C5 is connected between the bias terminal 25 and the ground. The bias circuit 24 supplies the drain bias voltage Vd supplied to the bias terminal 25 to the drain D and suppresses the passage of the high-frequency signal through the bias terminal 25. The matching circuit 26 includes an inductor L2 connected in series and a capacitor C2 connected in shunt. The matching circuit 28 includes an inductor L3 connected in series and a capacitor C3 connected in shunt. The matching circuits 26 and 28 can be appropriately formed using inductors and capacitors such as an LCL-T type circuit and a CLC-π type circuit. The matching circuits 26 and 28 may be formed using a distributed constant circuit. Other configurations are the same as those in FIG. 1 of the first embodiment, and the description thereof is omitted.

[0033] [Simulation] The high-frequency circuit 104 in the second embodiment was simulated. Simulations were performed on circuit A provided with the stabilization circuit 10 and circuit B not provided with the stabilization circuit 10. The simulation conditions are as follows. Operating frequency band: 3.4 GHz to 3.8 GHz Transistor 21: GaN HEMT R1: 50 Ω L1 (nH), C1 (pF): The values of the elements were selected so that the resonance frequency of the series resonance circuit composed of L1 and C1 was included within the frequency band where the stability factor K < 1 in circuit B not provided with the stabilization circuit 10.

[0034] FIG. 8 is a diagram showing S21 with respect to the frequency in circuit A. As shown in FIG. 8, S21 at frequencies of 3.4 GHz, 3.6 GHz, and 3.8 GHz are 15.358 dB , 15.636 dB and 14.971 dB respectively. Thus, in the operating band 54 of 3.4 GHz to 3.8 GHz, S21 is about 15 dB.

[0035] FIG. 9 is a diagram showing the stability coefficient K with respect to the frequency in circuit A. As shown in FIG. 9, the stability coefficient K becomes small near the operating band 54. This is because S21 is large near the operating band 54. Also, the stability coefficient K is small when the frequency is near 1 GHz. The stability coefficient K is 1 or more when the frequency is in the range of 1 GHz to 8 GHz. Accordingly, the high-frequency circuit 104 operates stably in the range of 1 GHz to 8 GHz.

[0036] Table 1 is a table showing the stability coefficient K and S21 in circuit A and circuit B. The stability coefficient K is the lowest K in the range of 1 GHz to 8 GHz, and S21 is the lowest S21 in the operating band of 3.4 GHz to 3.8 GHz.

Table 1

[0037] As shown in Table 1, in circuit B without the stabilization circuit 10, the stability coefficient K is 0.789. The stability coefficient K becomes the smallest near 1 GHz. The S21 of circuit B is 14.66 dB. In circuit A with the stabilization circuit 10, the stability coefficient K becomes 1.046. The stability coefficient K becomes the smallest at 3.6 GHz, and the stability coefficient K is 1 or more near 1 GHz. As described above, in circuit A, the gain S21 can be made to be 1 or more with almost no change in the stability coefficient K.

[0038] When the coupling line 16, the resonance circuit 12, and the resistance element 14 are not provided at the resonance frequency of the resonance circuit 12 as in circuit B, the stability coefficient K of the high-frequency circuit is less than 1. By providing the coupling line 16, the resonance circuit 12, and the resistance element 14 as in circuit A in such a high-frequency circuit, the stability coefficient K can be increased. The stability coefficient K at the resonance frequency of the resonance circuit 12 when the coupling line 16, the resonance circuit 12, and the resistance element 14 are not provided in the high-frequency circuit is 0.95 to When it is below or 0.9 or less, it is preferable to provide the coupling line 16, the resonance circuit 12, and the resistance element 14.

[0039] In a circuit like Circuit B, at frequencies lower than the band of the high-frequency circuit, the gain increases and the stability factor K tends to decrease. Therefore, it is preferable that the resonance frequency of the resonance circuit 12 is lower than the operating frequency band of the high-frequency circuit, more preferably 1 / 2 or less of the band, and even more preferably 1 / 3 or less of the band.

[0040] In Examples 1 and 2, an example of an FET such as a GaN HEMT was described as the transistor 21, but the transistor 21 may be a bipolar transistor. n When the transistor 21 is an FET, the input electrode is the gate, and the output electrode is the drain, the stability factor K tends to occur at frequencies lower than the operating band. Therefore, it is preferable to provide the stabilization circuit 10.

[0041] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the above meaning but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0042] 10 Stabilization circuit 12 Resonance circuit 14 Resistance element 16 Coupling line 18 Transmission line 20 Amplifier 21 Transistor 22, 24 Bias circuit 23, 25 Bias terminal 26, 28 Matching circuit 27 CR filter 30 Dielectric substrate 32, 34 Metal layer 32a~32g Pattern 35 Bonding material 36 Through electrode 38a~38c Electronic component 50, 52 High-frequency signals 54 Operating band 100, 102, 104, 110 High-frequency circuits S Source G Gate (input electrode) D Drain (output electrode)

Claims

**Claim 1**: A high-frequency circuit comprising: A transistor having an input electrode for inputting a high-frequency signal and an output electrode for outputting a high-frequency signal; A transmission line connected to either one of the input electrode and the output electrode and through which a high-frequency signal is transmitted; A coupling line provided electrically separated from the transmission line to such an extent that electromagnetic field coupling is possible with the transmission line; A resonance circuit connected between a first end of the coupling line and a reference potential and minimizing the impedance between the first end and the reference potential at a resonance frequency; Comprising A high-frequency circuit, wherein the resonance frequency of the resonance circuit is lower than the operating frequency band of the high-frequency circuit. **Claim 2**: Comprising a resistance element, The first end of the resistance element is connected to the second end of the coupling line, the second end of the resistance element is connected to a reference potential, and the resistance value of the resistance element is not less than 1 / 2 times and not more than 2 times the characteristic impedance of the coupling line at the center frequency of the operating frequency band of the high-frequency circuit. The high-frequency circuit according to Claim 1. **Claim 3**: An input terminal for inputting a high-frequency signal; A matching circuit for matching the input impedance of the input terminal and the input impedance of the input electrode. The high-frequency circuit according to Claim 1 or Claim 2, wherein the first end of the transmission line is connected to the matching circuit and the second end is connected to the input electrode. **Claim 4**: An output terminal for outputting a high-frequency signal; A matching circuit for matching the output impedance of the output electrode and the output impedance of the output terminal. The high-frequency circuit according to Claim 1 or Claim 2, wherein the first end of the transmission line is connected to the output electrode and the second end is connected to the matching circuit. **Claim 5**: The high-frequency circuit according to any one of Claims 1 to 4, wherein the input electrode is a gate and the output electrode is a drain. **Claim 6**: The high-frequency circuit according to any one of Claims 1 to 5, wherein the stability factor of the high-frequency circuit when the coupling line and the resonance circuit are not provided at the resonance frequency of the resonance circuit is less than 1. **Claim 7**: The high-frequency circuit according to any one of Claims 1 to 6, wherein the resonance circuit comprises an inductor and a capacitor connected in series between the first end of the coupling line and a reference potential. ​ ​

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