High frequency device and circuit board

Abstract

To miniaturize a high frequency amplifier having a second harmonic processing circuit.SOLUTION: The high-frequency device includes a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave in response to a high-frequency signal and a circuit substrate, and the circuit substrate includes a first transmission line 18a to one end of which the first voltage is applied, a second harmonic processing circuit including a second transmission line 118b one end of which is connected to the first transmission line, and a ground plane 38 disposed below the first transmission line and the second transmission line, and the second harmonic processing circuit suppresses generation of a second harmonic among harmonics in generation of the first voltage. The circuit substrate further includes a substrate 140 having a lower surface on which the ground plane is disposed, a first upper surface 44a which is located above the ground plane and on which the first transmission line is disposed, and a second upper surface 144b which is located above the ground plane, is closer to the ground plane than the first upper surface, and on which at least a part of the second transmission line is disposed.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a high-frequency device and a circuit board. [Background technology]

[0002] Gallium nitride high electron mobility transistors (GaN HEMTs) have a high breakdown voltage, allowing them to operate at high voltages. For this reason, GaN HEMTs are being developed as high-frequency amplifiers suitable for high-power applications.

[0003] High efficiency is important for high-power high-frequency amplifier elements. To increase the efficiency of high-frequency amplifier elements, it is effective to short-circuit the output electrode (e.g., drain electrode) of the high-frequency amplifier element with respect to even-order harmonics. Therefore, the output circuit of the high-frequency amplifier element is provided with a harmonic processing circuit that short-circuits even-order harmonics (see, for example, Patent Documents 1 and 2).

[0004] It should be noted that even devices that do not have high-frequency amplification elements exist that have circuits that process or generate second harmonics or frequency-doubled signals (see, for example, Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 64-47107 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-309198 [Patent Document 3] U.S. Patent No. 4,079,268 [Patent Document 4] US Patent Application Publication No. 2020 / 0280283 Summary of the Invention [Problem to be solved by the invention]

[0006] Even highly efficient high-frequency amplifier elements generate heat as their output power increases, resulting in a significant temperature rise. For this reason, high-power high-frequency amplifier elements are cooled to prevent performance degradation due to temperature rise.

[0007] A high-frequency amplifier element (e.g., GaN HEMT) is used as a device (hereinafter referred to as a high-frequency amplifier) ​​integrated with an input circuit and an output circuit. Therefore, when the high-frequency amplifier element is cooled, the entire high-frequency amplifier (i.e., the device including the input circuit, high-frequency amplifier element, and output circuit) is cooled.

[0008] Although the high-frequency amplifier element itself is small, the input and output circuits are not. Therefore, cooling the entire high-frequency amplifier consumes significant power. Therefore, miniaturizing the input and output circuits is important to reduce the energy consumption of systems equipped with high-frequency amplifiers.

[0009] As described above, in order to improve the efficiency of a high-frequency amplifier element (e.g., GaN HEMT), it is effective to place a harmonic processing circuit in the output circuit. However, placing a harmonic processing circuit in the output circuit increases the size of the output circuit. Therefore, an object of the present invention is to solve this problem. [Means for solving the problem]

[0010] In order to solve the above problem, in one embodiment, a high-frequency device includes: a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave in response to a high-frequency signal; and a circuit board, wherein the circuit board includes: a first transmission line to which the first voltage is applied at one end; a second transmission line having one end connected to the first transmission line; a ground plane arranged below the first transmission line and the second transmission line, and the second harmonic processing circuit is configured to suppress generation of a second harmonic among the harmonics in the generation of the first voltage; and the circuit board further includes a substrate having: a bottom surface on which the ground plane is arranged; a first top surface located above the ground plane and on which the first transmission line is arranged; and a second top surface located above the ground plane and closer to the ground plane than the first top surface, on which at least a portion of the second transmission line is arranged. [Effects of the Invention]

[0011] According to one aspect of the present invention, a high-frequency amplifier with high efficiency achieved by a second harmonic processing circuit can be miniaturized. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a plan view of an example 2 of a high-frequency device (hereinafter referred to as a microwave amplifier) ​​according to a first embodiment. [Figure 2] FIG. 2 is an example of a circuit diagram of the microwave amplifier 2. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a diagram showing a part of a cross section taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a diagram illustrating an example of a large-amplitude operation of a transistor. [Figure 6] FIG. 6 is a cross-sectional view of a microstrip line illustrating the variables in equation (3). [Figure 7] FIG. 7 is an enlarged plan view of a second harmonic wave processing section 12c and its vicinity in the comparative example 6c. [Figure 8] FIG. 8 is an enlarged plan view of second harmonic processing section 12 and its vicinity according to the first embodiment. [Figure 9] FIG. 9 is a table comparing the total line width a3 in the comparative example 6c with the total line width b3 in the output-side circuit board 6 of the first embodiment. [Figure 10] FIG. 10 is a plan view of an example of a high-frequency device according to the second embodiment. [Figure 11] FIG. 11 is a diagram showing a part of a cross section taken along line XI-XI in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and their equivalents. Parts having the same structure even in different drawings will be given the same reference numerals, and their description will be omitted.

[0014] (Embodiment 1) (1) Structure Fig. 1 is a plan view of an example 2 of a high-frequency device (hereinafter referred to as a microwave amplifier) ​​according to the first embodiment. Fig. 2 is an example of a circuit diagram of microwave amplifier 2. Fig. 2 also shows peripheral circuits of microwave amplifier 2 (specifically, DC voltage sources 36, 72 and transmission lines 15, 16).

[0015] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. In the plan view shown in Fig. 1, several portions of the microwave amplifier 2 (portions sandwiched between wavy lines) are omitted. The same applies to the cross-sectional view shown in Fig. 3.

[0016] The microwave amplifier 2 has a transistor 4 (e.g., a GaN HEMT) and a circuit board 6 (hereinafter referred to as an output-side circuit board: see FIGS. 1-3) connected to an output electrode D (e.g., a drain electrode of a GaN HEMT: see FIG. 2) of the transistor 4. The microwave amplifier 2 further has another circuit board 8 (hereinafter referred to as an input-side circuit board) connected to an input electrode G (e.g., a gate electrode of a GaN HEMT) of the transistor 4, and a conductive carrier 10 (hereinafter referred to as a conductive carrier).

[0017] From now on, the input electrode G will be called the gate electrode, and the output electrode D will be called the drain electrode.

[0018] (1-1) Transistor 4 The transistor 4 (see FIG. 2) generates a voltage Vd (hereinafter referred to as a first voltage or drain voltage) containing a fundamental wave and its harmonics in response to a high-frequency signal 26b input to the transistor 4 via the input-side circuit board 8. The high-frequency signal 26b (hereinafter referred to as a second high-frequency signal or input signal) is a high-frequency signal whose voltage and current vary at a specific frequency f1. The input signal 26b is typically a high-frequency signal (i.e., a sine wave) that does not contain harmonics.

[0019] The frequency f1 of the input signal 26b is, for example, 300 MHz or more and 300 GHz or less (the same applies to the first and third high-frequency signals, etc., described later). That is, the input signal 26b is, for example, a microwave. The frequency of the fundamental wave of the drain voltage Vd is the same as the frequency f1 of the input signal 26b.

[0020] The transistor 4 has a drain electrode D connected to the output circuit board 6 and a gate electrode G connected to the input circuit board 8. Furthermore, the transistor 4 has a source electrode S connected to the ground plane 38 of the output circuit board 6 and the ground plane 62 of the input circuit board 8, for example, via a conductive carrier 10 (see FIG. 3). The ground planes 38 and 62 are conductive films (for example, copper foil).

[0021] The drain voltage Vd (i.e., the first voltage) is the voltage between the source electrode S and the drain electrode D. That is, the drain voltage Vd is the potential Φ D and the potential Φ of the source electrode S S potential difference (=Φ D -Φ S )

[0022] The transistor 4 is, for example, a GaN HEMT having a multi-finger structure in which a plurality of small GaN HEMTs are arranged in parallel. The GaN HEMT is a high electron mobility transistor in which the electron transit layer is made of GaN and the electron supply layer is made of AlGaN.

[0023] When the transistor 4 has a multi-finger structure, the gate electrode G is, for example, an electrode to which the gate of each small GaN HEMT is connected, the drain electrode D is an electrode to which the drain of each small GaN HEMT is connected, and the source electrode S is, for example, an electrode to which the source of each small GaN HEMT is connected.

[0024] For clarity, a high frequency signal (eg, input signal 26b) is a wave of voltage and current propagating through a transmission line (eg, a microstrip line).

[0025] (1-2) Output side circuit board 6 -First transmission line 18a and drain connection pad 20d- The output-side circuit board 6 has a transmission line 18a (hereinafter referred to as a first transmission line) (see FIGS. 1 and 2), one end (hereinafter referred to as a left end) of which is applied a drain voltage Vd generated by the transistor 4. The output-side circuit board 6 further has a conductive pad 20d (hereinafter referred to as a drain connection pad) connected to the left end of the first transmission line 18a.

[0026] The output-side circuit board 6 further includes a conductive wire 22d (e.g., an Au wire) that connects the drain electrode D of the transistor 4 to the drain connection pad 20d. The drain voltage Vd is applied to the left end of the first transmission line 18a via the wire 22d and the drain connection pad 20d.

[0027] The first transmission line 18a is, for example, a microstrip line (the same applies to the second transmission line 18b, etc., described later). The characteristic impedance of the first transmission line 18a is, for example, 50 Ω. The characteristic impedance of the first transmission line 18a may be a value other than 50 Ω (for example, 25 Ω or 75 Ω). The same applies to the characteristic impedances of the second to fifth transmission lines 18b-18e, described later.

[0028] -2nd harmonic processing circuit 12- The output-side circuit board 6 further includes a second harmonic processing circuit 12 having a second transmission line 18b connected at one end to the first transmission line 18a. The second harmonic processing circuit 12 is configured to suppress the occurrence of a second harmonic when generating the drain voltage Vd.

[0029] The "double wave" is the harmonic with the lowest frequency among the harmonics of the drain voltage Vd. In other words, the "double wave" is a frequency component of the drain voltage Vd whose voltage changes at twice the frequency f1 of the fundamental wave of the drain voltage Vd (i.e., 2f1).

[0030] In the following description, unless otherwise specified, the double wave means the double wave of the drain voltage Vd. The detailed function of the double wave processing circuit 12 will be described later (see "(2) Operation").

[0031] The second harmonic processing circuit 12 is preferably an open stub having one end connected to the first transmission line 18a. In this case, the second harmonic processing circuit 12 is a second transmission line 18b having the other end open. The second transmission line 18b is, for example, a microstrip line having the same characteristic impedance (e.g., 50Ω) as the first transmission line 18a.

[0032] When the second transmission line 18b is an open stub, its length is preferably equal to the wavelength λ of a sine wave whose voltage and current change at a frequency 2f1 that is a double of the drain voltage Vd while propagating through the second transmission line 18b. 2f1 1 / 4 of (i.e., λ 2f1 / 4), but the wavelength λ 2f1 " is the wavelength of the sine wave while it is propagating through the second transmission line 18b (the same applies below).

[0033] The impedance of an open stub having the above length has an absolute value of 0Ω or approximately 0Ω at a frequency of 2f1. 2f1 The impedance of an open stub having a length 1 / 4 of that of the stub is 0 Ω (i.e., a short circuit) at frequency 2f1.

[0034] -Ground Plane 38- The output side circuit board 6 further includes a ground plane 38 (see FIGS. 2 and 3) disposed below the first transmission line 18a and the second transmission line 18b.

[0035] - Output section 24 - The output-side circuit board 6 further includes an output unit 24 (see FIGS. 1-3). The output unit 24 outputs a high-frequency signal 26a (hereinafter referred to as a first high-frequency signal) that is a high-frequency signal (e.g., microwave) propagating through the first transmission line 18a and that is generated by applying a drain voltage Vd to the left end of the first transmission line 18a (see FIGS. 1 and 2). The output unit 24 is, for example, a conductive pad.

[0036] -Output side matching circuit 14a- The output-side circuit board 6 (see FIG. 2) further includes a first matching circuit 14a (hereinafter referred to as the output-side matching circuit) including a part of the first transmission line 18a and the second harmonic processing circuit 12.

[0037] The output-side matching circuit 14a is a circuit configured to bring the impedance Zout of the microwave amplifier 2 as viewed from the right end of the output unit 24 at the frequency f1 of the fundamental wave of the drain voltage Vd closer to the characteristic impedance Z0 (for example, 50 Ω) of the transmission line 15. The transmission line 15 (see FIG. 2) is a transmission line connected to the output unit 24.

[0038] The "right end of the output section 24" is the boundary between the output section 24 and the transmission line 15. Since impedance is an imaginary number, "bringing the impedance Zout closer to the characteristic impedance Z0 (e.g., 50 Ω) of the transmission line 15" means reducing the absolute value of Zout - Z0.

[0039] In other words, the output-side matching circuit 14a is a circuit that suppresses the generation of reflected waves that occur when the third high-frequency signal 26c enters the output unit 24 from the transmission line 15 when the transmission line 15 has a specific characteristic impedance and is connected to the output unit 24. However, the third high-frequency signal 26c (see FIG. 2) is a sine wave whose voltage and current change at frequency f1 (i.e., a high-frequency signal that does not contain harmonics). The configuration of the output-side matching circuit 14a can vary depending on the circuit (including the transmission line 16) connected to the input unit 50, which will be described later.

[0040] The characteristic impedance of the transmission line 15 may be a value other than 50Ω (for example, 25Ω or 75Ω). The same applies to the transmission line 16 connected to the input unit 50.

[0041] The output-side matching circuit 14a includes, for example, an inductor 27 having one end connected to the right end of the first transmission line 18a (see FIG. 2), and a transmission line 18c (hereinafter referred to as a third transmission line) connected to the other end of the inductor 27. The output-side matching circuit 14a further includes a capacitor 28 having one end connected to the third transmission line 18c (see FIGS. 1 and 2) and the other end connected to a ground plane 38.

[0042] - Coupling Capacitor 29 - The output-side circuit board 6 further includes a coupling capacitor 29, one electrode of which is connected to the output section 24 and the other electrode of which is connected to one end 30 (hereinafter referred to as the right end) of the output-side matching circuit 14a. The coupling capacitor 29 passes the first high-frequency signal 26a (see FIG. 2) propagating through the first transmission line 18a, and blocks the bias voltage Vdb (hereinafter referred to as the output-side bias voltage) applied to the drain electrode D of the transistor 4.

[0043] The output-side circuit board 6 further includes a conductive wire 32 (e.g., an Au wire) that connects the "other electrode" of the coupling capacitor 29 to a right end 30 of the output-side matching circuit 14a. The right end 30 of the output-side circuit board 6 is, for example, one end of the third transmission line 18c to which the inductor 27 is connected.

[0044] - Output side bias circuit 34 - The output-side circuit board 6 further includes a bias circuit 34 (hereinafter referred to as the output-side bias circuit) having one end connected to the drain electrode D of the transistor 4 and the other end to which an output-side bias voltage Vdb is applied (see FIG. 2). In FIG. 1, the area occupied by the bias circuit 34 is indicated by a dashed line, and electronic components and the like included in the bias circuit 34 are not shown (the same applies to the bias circuit 70 and the input-side matching circuit 14b).

[0045] The output bias voltage Vdb is generated by a DC voltage source 36 (hereinafter referred to as a bias voltage source) and applied to the drain electrode D of the transistor 4 via an output bias circuit 34. The output bias circuit 34 is, for example, a decoupling inductor. The same applies to an input bias circuit 70 (see FIG. 2) described later.

[0046] The output side bias circuit 34 is a circuit that substantially shorts the drain electrode D of the transistor 4 and the bias voltage source 36 for direct current, and substantially opens the drain electrode D for high frequency signals (e.g., microwaves). The same applies to the input side bias circuit 70.

[0047] - Substrate 40 - The output-side circuit board 6 further has an insulating substrate 40 (see FIG. 3). FIG. 4 is a diagram showing a portion of a cross section taken along line IV-IV in FIG. 1. However, in FIG. 4, the conductive carrier 10 (e.g., a metal plate) is not shown. The substrate 40 is, for example, an insulating resin substrate, an alumina substrate, or a glass epoxy substrate. The same applies to a substrate 64 of the input-side circuit board 8, which will be described later.

[0048] The substrate 40 (see FIG. 4) has a bottom surface 42 on which the ground plane 38 is disposed, and a first top surface 44a located above the ground plane 38 and on which the first transmission line 18a is disposed. The substrate 40 further has a second top surface 44b located above the ground plane 38 and closer to the ground plane 38 than the first top surface 44a, and on which a portion of the second transmission line 18b is disposed. The substrate 40 further has a slope 46 located between the first top surface 44a and the second top surface 44b and forming an obtuse angle with the second top surface 44b.

[0049] The second transmission line 18b has a connection portion 48 that is in contact with the first transmission line 18a and has at least a portion disposed on the slope 46, and a portion 47 that is disposed on the second upper surface 44b. The connection portion 48 may extend onto either or both of the first and second upper surfaces 44a, 44b.

[0050] (1-3) Input side circuit board 8 The input side circuit board 8 transmits the input signal 26 b to the transistor 4 .

[0051] --Fourth transmission line 18d and gate connection pad 20g-- The input-side circuit board 8 has a transmission line 18d (hereinafter referred to as a fourth transmission line) that transmits the input signal 26b to the gate electrode G of the transistor 4 (see FIGS. 1 and 2). The input-side circuit board 8 further has a conductive pad 20g (hereinafter referred to as a gate connection pad) connected to one end of the fourth transmission line 18d.

[0052] The input-side circuit board 8 further includes a conductive wire 22g (for example, an Au wire) that connects the gate connection pad 20g and the gate electrode G. The input signal 26b is transmitted to the gate electrode G via the wire 22g and the gate connection pad 20g.

[0053] The fourth transmission line 18d is, for example, a microstrip line, and has a characteristic impedance of, for example, 50Ω.

[0054] -Ground Plane 62- The input-side circuit board 8 further includes a ground plane 62 (see FIGS. 2 and 3) disposed below the fourth transmission line 18d.

[0055] -Input section 50- The input-side circuit board 8 further includes an input section 50 to which the input signal 26b is incident. The input section 50 is, for example, a conductive pad (see FIGS. 1-3).

[0056] -Input side matching circuit 14b- The input-side circuit board 8 (see FIG. 2) further includes a second matching circuit 14b (hereinafter referred to as the input-side matching circuit) that includes a part of the fourth transmission line 18d.

[0057] The input-side matching circuit 14b is a circuit configured to bring the impedance Zin of the microwave amplifier 2 as viewed from the left end of the input section 50 at the frequency f1 of the fundamental wave of the drain voltage Vd closer to the characteristic impedance Z0 (for example, 50 Ω) of the transmission line 16. The transmission line 16 is a transmission line connected to the input section 50.

[0058] The "left end of the input section 50" is the boundary between the input section 50 and the transmission line 16. Since impedance is an imaginary number, "bringing the impedance Zin closer to the characteristic impedance Z0 (e.g., 50 Ω) of the transmission line 16" means reducing the absolute value of Zin - Z0.

[0059] In other words, the input-side matching circuit 14b is a circuit that suppresses the generation of reflected waves when the transmission line 16 having a specific characteristic impedance is connected to the input unit 50 and the input signal 26b not containing harmonics enters the input unit 50 from the transmission line 16. However, the configuration of the input-side matching circuit 14b may vary depending on the circuit (including the transmission line 15) connected to the output unit 24.

[0060] The input-side matching circuit 14b includes, for example, an inductor 52 having one end connected to the left end of the fourth transmission line 18d (see FIG. 2), and a transmission line 18e (hereinafter referred to as a fifth transmission line) connected to the other end of the inductor 52. The input-side circuit board 8 further includes a capacitor 54 having one end connected to the fifth transmission line 18e and the other end connected to the ground plane 62.

[0061] -Coupling Capacitor 56- The input-side circuit board 8 (see FIGS. 1-2) further includes a coupling capacitor 56, one electrode of which is connected to the input section 50 and the other electrode of which is connected to one end 58 (hereinafter referred to as the left end) of the input-side matching circuit 14b. The coupling capacitor 56 passes the input signal 26b (see FIG. 2) incident on the input section 50 and blocks the bias voltage Vgb (hereinafter referred to as the input-side bias voltage) applied to the gate electrode G of the transistor 4.

[0062] The input-side circuit board 8 (see FIG. 1) further includes a conductive wire 60 (e.g., an Au wire) that connects the "other electrode" of the coupling capacitor 56 to a left end 58 of the input-side matching circuit 14b. The left end 58 of the input-side circuit board 8 is, for example, one end of the fifth transmission line 18e to which the inductor 52 (see FIG. 2) is connected.

[0063] - Input side bias circuit 70 - The input-side circuit board 8 further includes a bias circuit 70 (hereinafter referred to as the input-side bias circuit) having one end connected to the input electrode G of the transistor 4 and the other end to which an input-side bias voltage Vgb is applied (see FIG. 2). The input-side bias voltage Vgb is generated by a DC voltage source 72 and applied to the gate electrode G of the transistor 4 via the input-side bias circuit 70.

[0064] - Substrate 64 - The input-side circuit board 8 further includes an insulating substrate 64 (see FIG. 3). The substrate 64 has a lower surface on which the ground plane 62 is disposed, and an upper surface located above the ground plane 62 and on which the fourth and fifth transmission lines 18d, 18e are disposed.

[0065] (2) Operation An input signal 26b incident on the input section 50 (see FIG. 2) passes through the input-side matching circuit 14b and is incident on the gate electrode G of the transistor 4. After passing through the coupling capacitor 56, the input-side bias voltage Vgb is superimposed on the input signal 26b incident on the gate electrode G.

[0066] An output bias voltage Vdb is applied to the drain electrode D of the transistor 4 via the first transmission line 18a. Because the impedance of the output bias circuit 34 is high in high frequency bands (e.g., microwave bands), the load impedance of the transistor 4 in high frequency bands is independent of the output bias circuit 34. Therefore, the load impedance of the transistor 4 is determined by the impedance of the output matching circuit 14a (more precisely, a circuit including the coupling capacitor 29, etc.).

[0067] Now consider a case where the voltage of the input signal 26b incident on the gate electrode G of the transistor 4 increases, causing the transistor 4 to operate in a large amplitude state. In this case, in response to the input signal 26b incident on the gate electrode G, the transistor 4 generates a drain voltage Vd that includes a fundamental wave and its harmonics.

[0068] The second harmonic processing circuit 12 has an impedance Z 2f1 The absolute value of the impedance Z at the frequency f1 of the fundamental wave of the drain voltage Vd f1 The absolute value of the impedance Z 2f1 " and "Impedance Z f1 ' is the impedance of the second harmonic processing circuit 12.

[0069] The magnitude of each frequency component of the drain voltage Vd is affected by the impedance of the second harmonic processing circuit 12 for each frequency component. The smaller the absolute value of the impedance for each frequency component, the greater the effect.

[0070] For example, if the absolute value of the impedance to the fundamental wave is sufficiently greater than 0Ω and the impedance to the second harmonic wave is 0Ω, the second harmonic processing circuit 12 has a limited effect on the generation of the fundamental wave but a large effect on the generation of the second harmonic wave. In other words, the second harmonic wave is not generated. This is because when the impedance of the second harmonic processing circuit 12 to the second harmonic wave is 0Ω, the drain electrode D is grounded to the second harmonic wave.

[0071] As this example shows, the second harmonic processing circuit 12 suppresses the occurrence of a second harmonic in the drain voltage Vd, resulting in high efficiency of the transistor 4 (see "--Suppression of second harmonic and high efficiency--").

[0072] As described above, the drain voltage Vd, in which the generation of the second harmonic is suppressed, is applied to the left end of the first transmission line 18a. As a result, a first high-frequency signal 26a, in which the generation of the second harmonic is suppressed, is generated. This first high-frequency signal 26a is output from the microwave amplifier 2 via the output-side matching circuit 14a and the like.

[0073] Impedance Z of the second harmonic processing circuit 12 for the second harmonic 2f1 The absolute value of the impedance Z of the second harmonic processing circuit 12 with respect to the fundamental wave is preferably f11 is less than 1 / 5 of the absolute value of

[0074] More preferably, the impedance Z of the second harmonic processing circuit 12 for the second harmonic 2f1 The absolute value of the impedance Z of the second harmonic processing circuit 12 with respect to the fundamental wave is preferably f11 is less than 1 / 10 of the absolute value of

[0075] Most preferably, the impedance Z of the second harmonic processing circuit 12 for the second harmonic 2f1 The absolute value of the impedance Z of the second harmonic processing circuit 12 with respect to the fundamental wave is preferably f11 is less than 1 / 20 of the absolute value of

[0076] If these conditions are met, the amplitude of the double wave voltage at the drain voltage Vd is 2f1 and the amplitude of the fundamental voltage V f1 Ratio to (= V 2f1 / V f1 ) becomes sufficiently small (for example, 1 / 10 or less).

[0077] To confirm, impedance Z 2f1 is the impedance of the second harmonic processing circuit 12 at the second harmonic frequency 2f1. Impedance Z f1 is the impedance of the second harmonic processing circuit 12 at the fundamental frequency f1.

[0078] -Length (physical length) and impedance of second transmission line 18b- As described above, when the second harmonic processing circuit 12 is an open stub, the length of the second transmission line 18b is preferably equal to or less than the wavelength λ of the sine wave whose voltage and current change at a frequency 2f1 while propagating through the second transmission line 18b. 2f1 However, the wavelength λ is between 0.9 and 1.1 times the wavelength λ. 2f1 is the wavelength of the sine wave while it is propagating through the second transmission line 18b.

[0079] In this case, the absolute value of the impedance of second harmonic processing circuit 12 (here, open stub) at frequency 2f1 is 0.19 times or less the absolute value of the impedance of second harmonic processing circuit 12 at frequency f1 (ie, the frequency of the fundamental wave).

[0080] More preferably, the length of the second transmission line 18b is set to a value equal to or larger than the wavelength λ of the sinusoidal wave whose voltage and current change at a frequency 2f1 while propagating through the second transmission line 18b. 2f1 1 / 4 of (i.e., λ 2f1 / 4). In this case, the absolute value of the impedance of second harmonic processing circuit 12 (here, an open stub) at frequency 2f1 is 0.09 times or less the absolute value of the impedance of second harmonic processing circuit 12 at frequency f1.

[0081] Most preferably, the length of the second transmission line 18b is equal to or less than the wavelength λ of the sinusoidal wave whose voltage and current change at a frequency 2f1 while propagating through the second transmission line 18b. 2f1 1 / 4 of (i.e., λ 2f1 / 4). In this case, the absolute value of the impedance of second harmonic processing circuit 12 (i.e., the open stub) at frequency 2f1 is 0.05 or less times the absolute value of the impedance of second harmonic processing circuit 12 at frequency f1.

[0082] There are various types of transistor operation, such as class A, class B, class AB, and class F. The operation of the transistor 4 is not limited to any of these multiple operations.

[0083] Class B, Class AB, and Class F are large signal operation modes. On the other hand, Class A operation mode is small signal operation mode. However, even in small signal operation, the operation of the transistor 4 is not completely linear. Therefore, even in Class A operation, the microwave amplifier 2 can be made highly efficient by using the second harmonic processing device 12.

[0084] - Suppression of second harmonic waves and high efficiency - Power added efficiency (PAE) is an index that indicates the efficiency of an amplifier, and is an index that indicates the efficiency with which the power (hereinafter referred to as DC input power) input to a transistor by a DC voltage source (e.g., bias voltage source 36) is converted into RF power as an output signal. The power added efficiency (PAE) is expressed by equation (1), where Pout is the output power of the transistor, Pin is the input power, and Pdc is the DC input power.

[0085] PAE=(Pout-Pin) / Pdc (1) Here, if the drain efficiency is defined as DE=Pout / Pdc and the power gain is defined as PE=Pout / Pin, then equation (1) can be transformed into equation (2).

[0086] PAE=DE(1-1 / PE) (2) Therefore, the power added efficiency (PAE) can be improved by increasing the drain efficiency (DE). In order to increase the drain efficiency (DE), it is necessary to reduce the amount of heat generated by the transistor (Pdc - Pout).

[0087] FIG. 5 is a diagram illustrating an example of large-amplitude operation of a transistor. The left vertical axis represents drain current Id. The right vertical axis represents drain voltage Vd. The horizontal axis represents time. In typical large-amplitude operation of a transistor (e.g., class B operation), the drain current Id is half-wave rectified, as shown in FIG. 5. Meanwhile, the drain voltage Vd has a valley while the drain current Id is flowing (the first half of the half-wave rectification, T1), and a peak while the drain current Id is not flowing (the second half of the half-wave rectification, T2).

[0088] The amount of heat generated by a transistor (Pdc - Pout) is not generated while the drain current Id is not flowing, but is generated while the drain current Id is flowing. Therefore, in order to reduce the amount of heat generated by a transistor (Pdc - Pout), it is effective to set the drain voltage Vd to 0 V while the drain current Id is flowing.

[0089] Based on Fourier series expansion, it is clear that the voltage that satisfies this requirement (i.e., the drain voltage Vd that is maintained at 0 V while the drain current Id is flowing) is a voltage that does not contain even-order harmonic components. Among these even-order harmonic components, the component with the largest amplitude is the double wave. Therefore, by suppressing the generation of the double wave, the efficiency of the transistor 4 can be improved.

[0090] (3) Miniaturization According to the first embodiment, the microwave amplifier 2, which has been made highly efficient by the second harmonic processing circuit 12, can be miniaturized while maintaining the match in characteristic impedance between the second harmonic processing circuit 12 and the first transmission line 18a.

[0091] Here, the case where the second transmission line 18b is a microstrip line is considered, but the conclusion is the same even if the second transmission line 18b is a transmission line other than a microstrip line (for example, a coplanar line).

[0092] The characteristic impedance Z0 of a microstrip line is expressed by equation (3). Figure 6 is a cross-sectional view of a microstrip line that explains the variables in equation (3).

[0093] Z0={87 / (1.41+ε r ) 1 / 2}×ln(5.98h / 0.8w+t) ···(3) where ε r is the relative permittivity of the substrate 74 (see FIG. 6). t is the thickness of the microstrip line 78. w is the width of the microstrip line 78 (hereinafter referred to as line width). h is the distance between the surface of the substrate on which the microstrip line 78 is arranged and the back surface of the substrate on which the ground plane 76 is arranged.

[0094] Narrowing the width of the second transmission line 18b of the second harmonic processing circuit 12 is an effective way to reduce the size of the output-side circuit board 6. However, as is clear from equation (3), narrowing the width of the second transmission line 18b (corresponding to the width w in FIG. 6) increases the characteristic impedance of the second transmission line 18b.

[0095] As a result, the characteristic impedance of the first transmission line 18a and the characteristic impedance of the second transmission line 18b do not match, causing a reflected wave, and as a result, the second harmonic processing circuit 12 is unable to fully perform its functions.

[0096] However, in the first embodiment, the distance h2 between the second upper surface 44b, on which most of the second transmission line 18b (see FIG. 4) is arranged, and the lower surface 42, on which the ground plane 38 is arranged, is narrower than the distance h1 between the first upper surface 44a, on which the first transmission line 18a is arranged, and the lower surface 42. Therefore, as is clear from equation (3), with the circuit board 6 according to the first embodiment, even if the width of the second transmission line 18b is narrowed, the characteristic impedance of the second transmission line 18b can maintain agreement with the characteristic impedance of the first transmission line 18a.

[0097] Therefore, according to the first embodiment, the microwave amplifier 2, which has been made highly efficient by the second harmonic processing circuit 12, can be made smaller while maintaining the match between the characteristic impedance of the second harmonic processing circuit 12 and the characteristic impedance of the first transmission line 18a.

[0098] It is possible to narrow the width of the second transmission line 18b while maintaining the same characteristic impedance by thinning the entire board, rather than thinning only the portion where the second transmission line 18b is located. However, in this case, the width of the first transmission line 18a is also narrowed, which increases the resistance of the first transmission line 18a. Such an output-side circuit board 6 is not preferable because it causes a large loss of high-frequency signals.

[0099] The distance h2 between the second upper surface 44b (see FIG. 4) on which the second transmission line 18b is arranged and the lower surface 42 on which the ground plane 38 is arranged is preferably equal to or less than half the distance h1 between the first upper surface 44a on which the first transmission line 18a is arranged and the lower surface 42.

[0100] More preferably, the distance h2 between the second upper surface 44b and the lower surface 42 is equal to or less than one-third of the distance h1 between the first upper surface 44a and the lower surface 42. Most preferably, the distance h2 between the second upper surface 44b and the lower surface 42 is equal to or less than one-quarter of the distance h1 between the first upper surface 44a and the lower surface 42.

[0101] 1 and 4, the second upper surface 44b is the bottom of a groove 80 (see FIG. 1) extending along the first transmission line 18a. However, the second upper surface 44b is not limited to the bottom of a groove. For example, the second upper surface 44b may be a flat surface that reaches the side surface of the circuit board 6.

[0102] (4) Comparative Example Consider an output-side circuit board (hereinafter referred to as a comparative example) in which the distance h1 between the first transmission line 18a and the ground plane 38 is equal to the distance h2 between the second transmission line 18b and the ground plane 38. In other words, the comparative example is a circuit board in which the thickness of the substrate 40 is uniform. Fig. 7 is an enlarged plan view of the second harmonic processing section 12c and its vicinity in this comparative example 6c.

[0103] The characteristic impedance of the first transmission line 18a is equal to the characteristic impedance of the second transmission line 18b. The length of the second transmission line 18b is set to be equal to the wavelength λ of the microwaves that propagate through the second transmission line 18b and whose voltage and current change at a frequency 2f1. 2f1 1 / 4 of (i.e., λ 2f1 / 4), where f1 is the frequency of the fundamental wave of the drain voltage Vd. The same applies to the frequency of the microwave propagating through the second transmission line 18b in FIG. 8, which will be described later.

[0104] a1 is the distance between the first transmission line 18a and the second transmission line 18b (hereinafter referred to as the line distance). a2 is the width of the second transmission line 18b (hereinafter referred to as the line width). a3 is the distance between the first transmission line 18a and the side of the second transmission line 18b that is farthest from the first transmission line 18a (hereinafter referred to as the total line width). a2 corresponds to w in FIG. 6.

[0105] 8 is an enlarged plan view of the second harmonic processing section 12 and its vicinity provided on the output-side circuit board 6 according to the first embodiment. b1 is the line spacing between the first transmission line 18a and the second transmission line 18b. b2 is the line width of the second transmission line 18b. b3 is the total line width of the first transmission line 18a and the second transmission line 18b. b2 corresponds to w in FIG. 6.

[0106] Fig. 9 is a table comparing the total line width a3 in Comparative Example 6c with the total line width b3 in the output-side circuit board 6 of Embodiment 1 (see the sixth column of Table 1). Fig. 9 also shows a comparison between the line width a2 in Comparative Example 6c and the line width b2 in the output-side circuit board 6 of Embodiment 1 (see the fifth column of Table 1).

[0107] The first and second columns of the second row of Table 1 show the spacings h1 and h2 (see FIG. 4) in comparative example 6c. The first and second columns of the third row show the spacings h1 and h2 (see FIG. 4) in output-side circuit board 6.

[0108] The length λ of the second transmission line 18b 2f1 The values ​​of / 4 (see column 3), track widths a2 and b2 (see column 5), and total track widths a3 and b3 (see column 6) are calculated values. The values ​​of the parameters other than h1 and h2 used in this calculation are as follows:

[0109] The frequency f1 of the fundamental wave is 3.6 GHz. The relative dielectric constant of the substrate 40 is 10. The thickness of the first and second transmission lines 18a, 18b is 3 μm. The line spacings a1, b1 are 0.3 mm, as shown in the fourth column of Table 1. The line spacings a1, b1 listed in the fourth column will be described later.

[0110] Note that the distance h1 between the first upper surface 44a (see FIG. 4) with which the first transmission line 18a is in contact and the lower surface 42 with which the ground plane 38 is in contact is also the distance between the first transmission line 18a and the ground plane 38. Therefore, the first row, first column of Table 1 uses the simple expression "distance h1 (mm) between the first transmission line and the ground plane." Furthermore, the distance h2 between the second upper surface 44b with which the second transmission line 18b is in contact and the lower surface 42 with which the ground plane 38 is in contact is also the distance between the second transmission line 18b and the ground plane 38. Therefore, the first row, second column of Table 1 uses the simple expression "distance h2 (mm) between the second transmission line and the ground plane."

[0111] As shown in the first and second columns of the second row, in comparative example 6c, the distance h2 between second transmission line 18b and ground plane 38 is equal to the distance h1 between first transmission line 18a and ground plane 38. On the other hand, in output-side circuit board 6 according to embodiment 1, the distance h2 between second transmission line 18b and ground plane 38 is 1 / 5 of the distance h1 between first transmission line 18a and ground plane 38 (see the first and second columns of the third row).

[0112] The line spacing a1, b1 (see the fourth column) was set to 0.3 mm, which is sufficient to suppress crosstalk between the first transmission line 18a and the second transmission line 18b. Various limitations (i.e., design limitations) are imposed on the design of a high-frequency circuit board. The line spacing a1, b1 is one of these design limitations.

[0113] Using these parameter values, the line widths a2 and b2 were calculated so that the characteristic impedance of the second transmission line 18b was equal to the characteristic impedance of the first transmission line 18a, 50Ω (see column 5). Furthermore, based on the calculated line widths a2 and b2 and the line spacings a1 and b1, the total line widths a3 and b3 were calculated.

[0114] As shown in Table 1, the total line width b3 (0.37 mm) of the output side circuit board 6 according to the first embodiment is less than half the total line width a3 (0.77 mm) of the comparative example 6c. As is clear from this, the microwave amplifier 2 according to the first embodiment can reduce the size of a microwave amplifier having a second harmonic processing circuit. Note that the parameter values ​​listed in Table 1 for the output side circuit board 6 are examples.

[0115] (5) Manufacturing method Next, an example of a method for manufacturing the microwave amplifier 2 will be described.

[0116] (5-1) Formation of the input side circuit board 8 (excluding the arrangement of the wires 60 and 22g) For example, a substrate (hereinafter referred to as a double-sided copper foil substrate) is prepared by attaching copper foil to both sides of an insulating resin substrate. Circuit wiring (i.e., an assembly of fifth transmission line 18e, input section 50, etc.) of input side circuit board 8 is formed on this double-sided copper foil substrate by a subtractive method. The subtractive method is a method of forming a circuit pattern by removing unnecessary portions of copper foil, etc.

[0117] Finally, electronic components such as capacitors 54 (see FIG. 2) and inductors 52 are soldered to the substrate on which the circuit pattern is formed. The copper foil on the back side of the double-sided copper foil board, on which the circuit pattern is not formed, becomes the ground plane 62.

[0118] Through the above steps, the portion of the input side circuit board 8 excluding the wires 60 and 22g (hereinafter referred to as an input side circuit board intermediate product) is completed.

[0119] (5-2) Formation of Output-Side Circuit Board 6 (excluding the arrangement of wires 32 and 22d) The method for forming the output-side circuit board 6 is similar to the method for forming the input-side circuit board 8. Therefore, explanations of the parts common to the method for forming the input-side circuit board 8 will be omitted or simplified.

[0120] First, the circuit wiring of the output side circuit board 6 (excluding the second transmission line 18b) is formed on one surface of the double-sided copper foil board by a subtractive method.

[0121] Thereafter, a groove 80 (see FIG. 1) is formed in the insulating portion (e.g., a resin substrate) of the double-sided copper foil substrate, with the bottom surface and one side surface of the second upper surface 44b (see FIG. 4) and the slope 46 meeting. The groove 80 (hereinafter referred to as a line groove) is formed, for example, by etching. The etching may be either dry etching or wet etching. The inclination angle of the slope 46 can be changed by adjusting the etching conditions.

[0122] When the line grooves 80 are formed by etching, the areas other than the areas that will become the line grooves 80 are covered with a photoresist film or the like. The line grooves 80 can also be formed by mechanically cutting a resin substrate or the like.

[0123] Next, the second transmission line 18b is formed by an additive method. The additive method is a method of forming a circuit pattern on an insulating substrate by plating or the like. The portions where the circuit pattern is not to be formed are covered with a photoresist film or the like. The second transmission line 18b has, for example, a Ni layer in contact with the substrate 40 and an Au layer formed on the Ni layer by plating.

[0124] Finally, electronic components such as capacitor 28 (see FIG. 2) and inductor 27 are soldered to the double-sided copper foil board on which the circuit pattern is formed. The copper foil on the back side of the double-sided copper foil board, on which the circuit pattern is not formed, becomes ground plane 38 (see FIG. 4).

[0125] Through the above steps, the portion of the output side circuit board 6 excluding the wires 32 and 22d (hereinafter referred to as an output side circuit board intermediate product) is completed.

[0126] (5-3) Mounting of circuit board intermediates on conductive carrier 10 First, the input side circuit board intermediate product, the output side circuit board intermediate product, and the transistor 4 are soldered to the conductive carrier 10.

[0127] Thereafter, the coupling capacitor 56 (see FIG. 1) mounted on the intermediate input circuit board is connected to the fifth transmission line 18e by a conductive wire 60. Furthermore, the gate connection pad 20g of the intermediate input circuit board is connected to the gate electrode G of the transistor 4 by a conductive wire 22g.

[0128] Finally, the coupling capacitor 29 mounted on the intermediate output circuit board is connected to the third transmission line 18c with a conductive wire 32. Furthermore, the drain connection pad 20d of the intermediate output circuit board is connected to the drain electrode D of the transistor 4 with a conductive wire 22d. Through the above steps, the microwave amplifier 2 is completed.

[0129] In the example shown here, the source electrode S of the transistor 4 is an electrode connected to the semiconductor substrate of the transistor 4. Therefore, the source electrode S is connected to the conductive carrier 10 by the above-mentioned soldering of the transistor 4.

[0130] (6) Variations (6-1) Variation 1 1-4, the input circuit board 8, the transistor 4, and the output circuit board 6 each have separate substrates. However, the input circuit board 8, the transistor 4, and the output circuit board 6 may share the substrate 40 (i.e., a substrate having a bottom surface 42, a first top surface 44a, and a second top surface 44b). In other words, the high-frequency device according to the first embodiment may be an MMIC (monolithic microwave integrated circuit).

[0131] For example, the high-frequency device according to the first embodiment may have a transistor 4 formed from a semiconductor layer on a sapphire substrate, an output circuit board including this sapphire substrate, and an input circuit board including the same sapphire substrate. Alternatively, the transistor 4 and the output circuit board 6 may share the substrate 40, and the input circuit board 8 may have a separate substrate.

[0132] (6-2) Variation 2 In the example described with reference to FIG. 1 etc., the second harmonic processing circuit 12 2f1 However, the second harmonic processing circuit according to the first embodiment is not limited to an open stub. For example, the second harmonic processing circuit according to the first embodiment may be configured as an open stub having a length of λ 2f1 Alternatively, the second harmonic processing circuit according to the first embodiment may include an electronic component (for example, an inductor or a capacitor) connected to the second transmission line 18b.

[0133] (6-3) Variation 3 1 and the like, the second harmonic processing circuit 12 is included in the output-side matching circuit 14a. However, the second harmonic processing circuit 12 does not have to be included in the output-side matching circuit 14a. For example, the second harmonic processing circuit 12 may be included in a filter circuit arranged between the transistor 4 and the output-side matching circuit 14a.

[0134] As described above, in the first embodiment, the second harmonic processing circuit is arranged on the second upper surface closer to the ground plane than the first surface on which the first transmission line, to one end of which the output voltage of the transistor is applied, is arranged. Therefore, according to the first embodiment, the width of the second transmission line 18b of the second harmonic processing circuit 12 can be narrowed, and therefore the microwave amplifier 2, which has been made more efficient by the second harmonic processing circuit 12, can be made smaller.

[0135] (Embodiment 2) The second embodiment is similar to the first embodiment, so the description of the same configuration as the first embodiment will be omitted or simplified.

[0136] Fig. 10 is a plan view of an example of a high-frequency device according to the second embodiment (hereinafter referred to as microwave amplifier 102). Fig. 11 is a diagram showing a part of a cross section taken along line XI-XI in Fig. 10. However, in Fig. 11, conductive carrier 10 (e.g., a metal plate) is not shown.

[0137] As shown in FIG. 10, a microwave amplifier 102 according to the second embodiment has a conductive wire 120 (for example, an Au wire) that connects a first transmission line 18a and a second transmission line 118b.

[0138] The second transmission line 118b has both ends disposed on the second upper surface 144b (see FIG. 11) and a connection part 148 (see FIG. 10) that includes one of the ends. The conductive wire 120 connects the first transmission line 18a and the connection part 148.

[0139] The manufacturing method according to the second embodiment is similar to the manufacturing method according to the first embodiment. However, the line groove 180 formed in the output-side circuit board 106 does not need to have the slope 46 (see FIG. 4), and therefore the entire line groove 180 may be formed to extend along the first transmission line 18a. The second transmission line 118b according to the second embodiment is formed on the bottom of such line groove 180 (i.e., the second upper surface 144b), including the connection portion 148.

[0140] Since the second transmission line 118b is formed at the bottom of the groove (i.e., the line groove 180) in the substrate 140, according to the second embodiment, it is possible to miniaturize the microwave amplifier having the second harmonic processing circuit, similar to the first embodiment. Furthermore, according to the second embodiment, it is not necessary to form the connection portion 48 (see FIG. 4) on the slope of the line groove 180, which makes it easier to form the second transmission line 118b.

[0141] Although the embodiments of the present invention have been described above, the embodiments 1-2 are merely examples and are not limiting. For example, the second transmission lines 18b, 118b according to the embodiments 1-2 (excluding the connection portion 48 according to the first embodiment) extend along the first transmission line 18a. However, the second transmission lines 18b, 118b according to the present invention may be perpendicular to the first transmission line 18a.

[0142] Furthermore, the first and second transmission lines 18a, 18b, and 118b according to embodiment 1-2 are microstrip lines, but may be coplanar lines.

[0143] The output-side matching circuit 14a according to embodiment 1-2 includes electronic components such as a capacitor and an inductor. However, the output-side matching circuit 14a according to embodiment 1-2 does not need to include these electronic components. For example, the output-side matching circuit 14a according to embodiment 1-2 may be a circuit including only a transmission line (e.g., a circuit including a λ / 4 transformer). The same applies to the input-side matching circuit 14b.

[0144] In the examples shown in FIGS. 3-4, the substrates 40, 64 have only one plate-shaped insulator. However, the substrates 40, 64 are not limited to such substrates. For example, the substrates 40, 64 may have a plate-shaped insulator and insulating films covering both sides of the insulator. Alternatively, the substrates 40, 64 may have an internal layer on which a microwave circuit is formed. Alternatively, the substrates 40, 64 may be a portion (e.g., the top layer) of a substrate in which multiple layers are stacked.

[0145] The following additional notes are disclosed regarding the above-described embodiment 1-2.

[0146] (Appendix 1) a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave in response to a high frequency signal; a second harmonic processing circuit including a first transmission line having one end to which the first voltage is applied and a second transmission line having one end connected to the first transmission line; and a circuit board having a ground plane disposed below the first transmission line and the second transmission line; the second harmonic processing circuit is configured to suppress generation of a second harmonic among the harmonics in the generation of the first voltage; The circuit board further includes a substrate having a bottom surface on which the ground plane is disposed, a first top surface located above the ground plane and on which the first transmission line is disposed, and a second top surface located above the ground plane and closer to the ground plane than the first top surface, on which at least a portion of the second transmission line is disposed. High frequency device.

[0147] (Appendix 2) The absolute value of the impedance of the second harmonic processing circuit at the frequency of the second harmonic is 1 / 5 or less of the absolute value of the impedance of the second harmonic processing circuit at the frequency of the fundamental wave. 2. The high-frequency device according to claim 1,

[0148] (Appendix 3) The distance between the second upper surface and the lower surface is equal to or less than half the distance between the first upper surface and the lower surface. 3. A high-frequency device according to claim 1 or 2.

[0149] (Appendix 4) the substrate further has an inclined surface located between the first upper surface and the second upper surface and forming an obtuse angle with the second upper surface, The second transmission line has a connection portion that is in contact with the first transmission line and at least a portion of which is disposed on the slope. 3. A high-frequency device according to claim 1 or 2.

[0150] (Appendix 5) further comprising a conductive wire connecting the first transmission line and the second transmission line; the second transmission line has both ends disposed on the second top surface and a connection portion including one of the both ends; The wire connects the first transmission line and the connection portion. 3. A high-frequency device according to claim 1 or 2.

[0151] (Appendix 6) a circuit board connected to a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave, a first transmission line to one end of which the first voltage is applied; a second harmonic processing circuit having a second transmission line connected at one end to the first transmission line; a ground plane disposed below the first transmission line and the second transmission line; a substrate having a bottom surface on which the ground plane is disposed, a first top surface located above the ground plane and on which the first transmission line is disposed, and a second top surface located above the ground plane and closer to the ground plane than the first top surface, on which at least a portion of the second transmission line is disposed; The second harmonic processing circuit is configured to suppress generation of a second harmonic among the harmonics in the generation of the first voltage. Circuit board.

[0152] (Appendix 7) The transistor and the circuit board share the substrate. 3. The high-frequency device according to claim 1 or 2.

[0153] (Appendix 8) the second transmission line is an open stub having one end connected to the first transmission line, the length of the second transmission line is 0.9 to 1.1 times a quarter of the wavelength of a sine wave whose voltage and current change at the frequency of the double wave while propagating through the second transmission line; The wavelength is a wavelength during the time when the sine wave is propagating through the second transmission line. 3. A high-frequency device according to claim 1 or 2.

[0154] (Appendix 9) Further, another circuit board is provided for transmitting a second high-frequency signal, the voltage and current of which change at the frequency of the fundamental wave, to the transistor; the transistor generates the first voltage in response to the second high frequency signal; the circuit board further includes an output section that outputs a first high-frequency signal that is propagated through the first transmission line and is generated by the application of the first voltage, and a first matching circuit; the other circuit board has an input section to which the second high-frequency signal is incident and a second matching circuit different from the first matching circuit, the first matching circuit is a circuit configured to suppress the generation of a reflected wave when a transmission line having a specific characteristic impedance is connected to the output section and a third high-frequency signal, which is a sine wave whose voltage and current change at the frequency of the fundamental wave, is incident on the output section from the transmission line; The second matching circuit is a circuit configured to suppress the generation of reflected waves that occur when another transmission line having a specific characteristic impedance is connected to the input part and the second high-frequency signal that does not contain harmonics is incident on the input part from the other transmission line. 3. The high-frequency device according to claim 1 or 2.

[0155] (Appendix 10) the first matching circuit includes a portion of the first transmission line and the second harmonic processing circuit; 10. The high-frequency device according to claim 9. [Explanation of symbols]

[0156] 2: Microwave amplifier (high frequency amplifier) 4: Transistor 6: Output circuit board 8: Input side circuit board 14a: Output matching circuit 14b: Input matching circuit 18a: First transmission line 18b: Second transmission line 24: Output section 26a: First high frequency signal 26b: Second high frequency signal 26c: Third high frequency signal 38: Ground plane 40: Substrate 42:Bottom surface 44a: 1st top surface 44b: 2nd top surface 46: Slope 48: Connection part 50: Input section 62: Ground plane 64: Circuit board 102: Microwave amplifier 106: Output circuit board 118b: Second transmission line 144b: 2nd top surface 148: Connection

Claims

1. a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave in response to a high frequency signal; a circuit board having a second harmonic processing circuit including a first transmission line having one end to which the first voltage is applied and a second transmission line having one end connected to the first transmission line, and a ground plane arranged below the first transmission line and the second transmission line; the second harmonic processing circuit is configured to suppress generation of a second harmonic among the harmonics in the generation of the first voltage; The circuit board further includes a substrate having a bottom surface on which the ground plane is disposed, a first top surface located above the ground plane and on which the first transmission line is disposed, and a second top surface located above the ground plane and closer to the ground plane than the first top surface, on which at least a portion of the second transmission line is disposed. High frequency device.

2. The absolute value of the impedance of the second harmonic processing circuit at the frequency of the second harmonic is 1 / 5 or less of the absolute value of the impedance of the second harmonic processing circuit at the frequency of the fundamental wave.

2. The high frequency device according to claim 1.

3. The distance between the second upper surface and the lower surface is equal to or less than half the distance between the first upper surface and the lower surface.

3. The high frequency device according to claim 1 or 2.

4. the substrate further has an inclined surface located between the first upper surface and the second upper surface and forming an obtuse angle with the second upper surface, the second transmission line has a connection portion that is in contact with the first transmission line and at least a portion of which is disposed on the inclined surface; 3. The high frequency device according to claim 1 or 2.

5. further comprising a conductive wire connecting the first transmission line and the second transmission line; the second transmission line has both ends disposed on the second top surface and a connection portion including one of the both ends; The wire connects the first transmission line and the connection portion.

3. The high frequency device according to claim 1 or 2.

6. a circuit board connected to a transistor that generates a first voltage including a fundamental wave and a harmonic of the fundamental wave, a first transmission line to one end of which the first voltage is applied; a second harmonic processing circuit having a second transmission line connected at one end to the first transmission line; a ground plane disposed below the first transmission line and the second transmission line; a substrate including a bottom surface on which the ground plane is disposed, a first top surface located above the ground plane and on which the first transmission line is disposed, and a second top surface located above the ground plane and closer to the ground plane than the first top surface, on which at least a portion of the second transmission line is disposed; The second harmonic processing circuit is configured to suppress generation of a second harmonic among the harmonics in the generation of the first voltage. Circuit board.

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