High frequency amplifier

Abstract

A high-frequency amplifier has a first transistor and a second transistor, a first drain pad connected to the first transistor and a second drain pad connected to the second transistor, a matching circuit pattern having a first transmission line connected to the first drain pad and a second transmission line connected to the second drain pad, a first lead and a second lead, and a wiring pattern connected to the first drain pad via the first transmission line and the first lead and connected to the second drain pad via the second transmission line and the second lead. An effective impedance of the second lead is larger than an effective impedance of the first lead. The matching circuit pattern has an asymmetric outer shape. An electrical length of the second transmission line is shorter than an electrical length of the first transmission line.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a high-frequency amplifier.

[0002] This application claims priority based on Japanese Application No. 2020-076598 filed on April 23, 2020, and the entire disclosure of which is incorporated herein by reference. BACKGROUND

[0003] As a high-frequency amplifier, for example, a technology related to a field effect transistor (FET) is disclosed in Patent Literature 1. The field effect transistor has a plurality of amplification elements for amplifying a high-frequency (RF) signal, and a matching circuit connected to an input terminal of the amplification element and an input terminal of a package via a bonding wire, which performs impedance conversion.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 63-86904 SUMMARY

[0007] The present disclosure provides a high-frequency amplifier. The high-frequency amplifier includes: a first transistor, a second transistor arranged side by side with the first transistor in a first direction, and a third transistor arranged side by side with the second transistor in the first direction on the side opposite to the first transistor; a first drain pad electrically connected to a drain electrode of the first transistor, a second drain pad electrically connected to a drain electrode of the second transistor, and a third drain pad electrically connected to a drain electrode of the third transistor; a matching circuit pattern having a first transmission line electrically connected to the first drain pad, a second transmission line electrically connected to the second drain pad, and a third transmission line electrically connected to the third drain pad, for performing impedance matching of a high-frequency signal for each of the first transistor, the second transistor, and the third transistor; a first lead line electrically connecting the first transmission line and the first drain pad, a second lead line electrically connecting the second transmission line and the second drain pad, and a third lead line electrically connecting the third transmission line and the third drain pad; and a wiring pattern electrically connected to the first drain pad via the first transmission line and the first lead line, and electrically connected to the second drain pad via the second transmission line and the second lead line. An effective impedance of the second lead line is larger than an effective impedance of the first lead line. The matching circuit pattern has an asymmetric shape with respect to a second imaginary straight line that is orthogonal to a first imaginary straight line connecting a first connection point of the first transmission line connected to the first lead line and a second connection point of the second transmission line connected to the second lead line, and that passes through a midpoint of the first connection point and the second connection point. An electrical length of the second transmission line is shorter than an electrical length of the first transmission line. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a plan view showing the internal configuration of the high-frequency amplifier 1A of the first embodiment and the high-frequency amplifier 1B of the second embodiment.

[0009] Figure 2 is a plan view showing the amplifying element 11 and the matching circuit 50.

[0010] Figure 3 is a plan view showing the amplifying element 11 and the matching circuit 50. Figure 2 is a plan view showing one of the matching circuit patterns 52 in

[0011] Figure 4 is a perspective view for explaining the electrical lengths of the bonding wires W41, W42, W43, W44, W45, W46, W47, and W48.

[0012] Figure 5 is a Smith chart showing the impedances of the bonding wires W41, W42, W43, W44, W45, W46, W47, and W48.

[0013] Figure 6is a graph showing imaginary parts of each impedance of the bonding wires W41, W42, W43, W44, W45, W46, W47, W48.

[0014] Figure 7 is a graph for explaining a relationship between a length of a physical path through which an electromagnetic wave passes and a phase.

[0015] Figure 8 is a graph for explaining a relationship between a length of a physical path through which an electromagnetic wave passes and a phase.

[0016] Figure 9 is a graph for explaining a distribution state of a current in a microwave.

[0017] Figure 10 is a simulation graph showing a concentration state of a current in a microwave.

[0018] Figure 11 is a simulation graph showing a distribution state of an electric field intensity in a microwave.

[0019] Figure 12 is a plan view showing one reference example of the pattern 80A through which an electromagnetic wave passes.

[0020] Figure 13 is a plan view showing another reference example of the pattern 80B through which an electromagnetic wave passes.

[0021] Figure 14 is a graph showing a phase difference generated between two electromagnetic waves that have respectively passed the paths DA, DB in the patterns 80A, 80B.

[0022] Figure 15 is a plan view showing the matching circuit 60.

[0023] Figure 16 is a plan view showing one matching circuit pattern 62 in the Figure 15 is a plan view showing one matching circuit pattern 62 in the

[0024] Figure 17 is a Smith chart showing each load impedance in the transistors 13A, 13B, 13C, 13D of the high-frequency amplifier 1B of the second embodiment.

[0025] Figure 18 is a graph showing a relationship between a phase unevenness of the load impedance and a power efficiency in the second embodiment.

[0026] Figure 19 is a plan view showing the matching circuit 60X of the high-frequency amplifier of the comparative example.

[0027] Figure 20is a Smith chart showing each load impedance in the transistors 13A, 13B, 13C, 13D of the high-frequency amplifier of the comparative example.

[0028] Figure 21 is a graph showing the relationship between the unevenness of the phase and the power efficiency of the load impedance in the comparative example. DETAILED DESCRIPTION

[0029] [Problem to be Solved by the Disclosure]

[0030] In the high-frequency amplifier disclosed in Patent Literature 1, a plurality of transistors are arranged in parallel in the amplifying element, and each of the transistors is connected to a matching circuit by a lead wire or the like. In such a case, the mutual inductance component of each of the plurality of lead wires is affected from the other lead wires in proximity. Thus, among the plurality of lead wires, unevenness in the effective impedance can occur depending on the degree of the influence from the other lead wires. At this time, among the plurality of lead wires, the phase of the RF signal is uneven, and thus unevenness in the phase of the RF signal can occur among the plurality of transistors. In order to improve the power efficiency of the high-frequency amplifier, it is desirable to reduce the unevenness in the phase of the RF signal.

[0031] [Effect of the Disclosure]

[0032] The high-frequency amplifier according to one embodiment of the disclosure can reduce the unevenness in the phase of the RF signal among the plurality of transistors.

[0033] [Explanation of Embodiments of the Disclosure]

[0034] First, the contents of an embodiment of the present disclosure are listed to be described. A high-frequency amplifier of one embodiment includes a first transistor, a second transistor arranged side by side with the first transistor in a first direction, and a third transistor arranged side by side with the second transistor in the first direction on the side opposite to the first transistor; a first drain pad electrically connected to a drain electrode of the first transistor, a second drain pad electrically connected to a drain electrode of the second transistor, and a third drain pad electrically connected to a drain electrode of the third transistor; a matching circuit pattern including a first transmission line electrically connected to the first drain pad, a second transmission line electrically connected to the second drain pad, and a third transmission line electrically connected to the third drain pad, for performing impedance matching of a high-frequency signal for each of the first transistor, the second transistor, and the third transistor; a first lead line electrically connecting the first transmission line and the first drain pad, a second lead line electrically connecting the second transmission line and the second drain pad, and a third lead line electrically connecting the third transmission line and the third drain pad; and a wiring pattern electrically connected to the first drain pad via the first transmission line and the first lead line, and electrically connected to the second drain pad via the second transmission line and the second lead line. An effective impedance of the second lead line is larger than an effective impedance of the first lead line. The matching circuit pattern has an asymmetric shape with respect to a second imaginary straight line that is orthogonal to a first imaginary straight line connecting a first connection point at which the first transmission line is connected to the first lead line and a second connection point at which the second transmission line is connected to the second lead line, and passes through a midpoint of the first connection point and the second connection point. An electrical length of the second transmission line is shorter than an electrical length of the first transmission line.

[0035] In the high-frequency amplifier, the first transistor, the second transistor, and the third transistor, which are the plurality of transistors, are connected to the matching circuit pattern through the first lead line, the second lead line, and the third lead line, which are the plurality of lead lines. In this configuration, unevenness in effective impedance can occur among the plurality of lead lines depending on the degree of influence from another lead line. Such unevenness in effective impedance among the plurality of lead lines can be expressed as unevenness in electrical length among the plurality of lead lines. In this high-frequency amplifier, the matching circuit pattern has an asymmetric shape, and thus the electrical length of the second transmission line is shorter than the electrical length of the first transmission line. Thus, in the configuration in which the electrical length of the second lead line is longer than the electrical length of the first lead line, the difference in electrical length among the lead lines can be eliminated by the difference in electrical length among the transmission lines. Thus, unevenness between the electrical length from the first transistor to the wiring pattern and the electrical length from the second transistor to the wiring pattern is reduced. The smaller the unevenness in electrical length among the plurality of lead lines, the smaller the unevenness in effective impedance among the plurality of lead lines, and thus the configuration can reduce unevenness in phase between the first transistor and the second transistor.

[0036] In the high-frequency amplifier described above, it can also be that the matching circuit pattern has a first land including a first corner portion and a second land including a second corner portion, the first transmission line is constituted by a portion of the first land including the first corner portion, the second transmission line is constituted by a portion of the second land including the second corner portion, and the second corner portion is chamfered at a chamfer amount greater than that of the first corner portion. According to the inventor's insight, under high frequencies, current (electric field) tends to concentrate on the outer edge of a conductor. Therefore, in the first transmission line, a high-frequency signal propagates along the first corner portion in the first land, and in the second transmission line, a high-frequency signal propagates along the second corner portion in the second land. Here, the second corner portion is chamfered at a chamfer amount greater than that of the first corner portion, and therefore, the path including the second corner portion is shorter than the path including the first corner portion, enabling a configuration in which the electrical length of the second transmission line is shorter than that of the first transmission line. Furthermore, according to this configuration, it is easy to match the electrical length from the first transistor to the wiring pattern and the electrical length from the second transistor to the wiring pattern by adjusting the chamfer amount. Therefore, it is possible to more reliably reduce unevenness in phase between the first transistor and the second transistor.

[0037] In the high-frequency amplifier described above, it can also be that the first transmission line is thinner than the second transmission line. In this case, it is possible to make the impedance per unit length of the first transmission line greater than the impedance per unit length of the second transmission line, and therefore, it is possible to achieve a configuration in which the electrical length of the second transmission line is shorter than that of the first transmission line. Furthermore, it is easy to match the electrical length from the first transistor to the wiring pattern and the electrical length from the second transistor to the wiring pattern by the degree to which the first transmission line is made thin. Therefore, it is possible to more reliably reduce unevenness in phase between the first transistor and the second transistor.

[0038] In the high-frequency amplifier described above, it can also be that a plurality of transistor groups configured to include a first transistor, a second transistor, and a third transistor are provided. In this case, it is possible to achieve a high-frequency amplifier with high output.

[0039] In the high-frequency amplifier described above, it can also be that a first lead wire is disposed at the outermost portion of the transistor group, and a second lead wire is disposed between the third lead wire and the first lead wire, the length of the first lead wire is equal to the length of the second lead wire, and the effective electrical length from the first drain land to the wiring pattern is substantially equal to the effective electrical length from the second drain land to the wiring pattern. In this case, the phases are substantially identical between the first transistor and the second transistor, and therefore, it is particularly advantageous from the viewpoint of improving the power efficiency of the high-frequency amplifier.

[0040] [Details of Embodiments of the Present Disclosure]

[0041] A specific example of a high-frequency amplifier according to one 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 illustrated by the claims, and is intended to include all modifications within the meaning and scope equivalent to those of the claims. In the following description, the same reference numerals are sometimes attached to the same elements or elements having the same function, and repetitive description is omitted. In the description, the XYZ orthogonal coordinate system shown in the drawings is sometimes referred to.

[0042] Figure 1 is a plan view showing the internal configuration of the high-frequency amplifier 1A of the first embodiment and the high-frequency amplifier 1B of the second embodiment. First, the high-frequency amplifier 1A of the first embodiment will be described. The high-frequency amplifier 1A includes one input terminal 2, one output terminal 3, an amplifying element portion 10, a branching circuit substrate 20, a combining circuit substrate 30, a matching circuit 40, and a matching circuit 50. In this embodiment, as one example, the high-frequency amplifier 1A has two matching circuits 40, 50 each. Further, the amplifying element portion 10 includes two amplifying elements 11. The output of each of the amplifying elements 11 is, for example, 30 W, and the output of the entire amplifying element portion 10 is, for example, 60 W. The high-frequency amplifier 1A includes a package 4 that houses the amplifying element portion 10, the branching circuit substrate 20, the combining circuit substrate 30, and the matching circuits 40, 50, and bonding wires W1, W2, W3, W4, W5, and W6.

[0043] The package 4 is made of metal and is connected to a reference potential. The package 4 has a substantially rectangular plan view. The package 4 has side walls 4c and 4d opposing each other in a first direction and end walls 4a and 4b opposing each other in a second direction. The first direction and the second direction cross each other, and in one example, are orthogonal to each other. In this embodiment, the first direction is the X-axis direction, and the second direction is the Y-axis direction.

[0044] The package 4 has a flat bottom plate 4e that is rectangular. The bottom plate 4e extends along a plane defined by the Y-axis direction and the X-axis direction. The end walls 4a and 4b are provided upright along a pair of edges of the bottom plate 4e (edges extending in the X-axis direction), and the side walls 4c and 4d are provided upright along another pair of edges of the bottom plate 4e (edges extending in the Y-axis direction). Note that the package 4 also has a not-shown cover portion. The cover portion closes an upper opening formed by the end walls 4a and 4b and the side walls 4c and 4d.

[0045] The input terminal 2 is a metal wiring pattern that inputs a high-frequency signal from the outside of the high-frequency amplifier 1A. The high-frequency signal is a signal based on a multi-carrier transmission system, and is a signal in which a plurality of carrier signals having different frequencies from each other are superimposed. The frequency band of the carrier signal is, for example, 500 MHz or less. The input terminal 2 is provided at the central portion of the end wall 4a in the X-axis direction, and extends from the outside to the inside of the package 4.

[0046] The output terminal 3 is a metal wiring pattern that outputs an amplified high-frequency signal to the outside of the high-frequency amplifier 1A. The output terminal 3 is provided at the central portion of the end wall 4b in the X-axis direction, and extends from the inside to the outside of the package 4.

[0047] The amplifying element portion 10 is disposed on the bottom plate 4e of the package 4 and at the substantially central portion of the package 4 in the Y-axis direction. Two amplifying elements 11 in the amplifying element portion 10 are disposed side by side in the X-axis direction. The amplifying element 11 has a plurality of transistors 13 (see FIG. 2). The plurality of transistors 13 are, for example, field effect transistors (FETs), and are, in one embodiment, high electron mobility transistors (HEMTs). The plurality of transistors 13 each have a gate electrode, a source electrode, and a drain electrode. Each transistor 13 amplifies an input high-frequency signal and outputs an amplified high-frequency signal. Note that a more specific configuration of the amplifying element 11 will be described later. Figure 2

[0048] The branch circuit substrate 20 is disposed on the bottom plate 4e of the package 4. The branch circuit substrate 20 is disposed side by side with the input terminal 2 and the amplifying element portion 10 in the Y-axis direction, and is located between the input terminal 2 and the amplifying element portion 10. The branch circuit substrate 20 has a ceramic substrate 21 and a branch circuit 22 provided on a main surface of the substrate 21. The substrate 21 has, for example, a rectangular shape in plan view, one long side 21a faces the input terminal 2, and the other long side 21b faces the amplifying element portion 10 with the matching circuit 40 interposed therebetween. The back surface of the substrate 21 faces the bottom plate 4e of the package 4. One short side 21c of the substrate 21 is located near the side wall 4c of the package 4, and the other short side 21d of the substrate 21 is located near the side wall 4d of the package 4. That is, the substrate 21 extends from near one end of the package 4 to near the other end in the X-axis direction.

[0049] ​Branch circuit 22 includes a wiring pattern 23 disposed on the main surface of substrate 21. Wiring pattern 23 is electrically connected to input terminal 2 via bonding line W1. High-frequency signals are input to wiring pattern 23 from the center of substrate 21 in the X-axis direction. Wiring pattern 23 has a shape that is linearly symmetrical about the center line of substrate 21 along the Y-axis direction. Wiring pattern 23 repeatedly branches from the connection point with bonding line W1, eventually reaching eight metal pads 23a. The eight metal pads 23a are arranged side by side along the long side 21b. Adjacent metal pads 23a are connected to each other via film resistors, forming Wilkinson couplers. This ensures isolation between the multiple gate pads 14 (described later) of amplifying element section 10 and achieves matching of the input impedance of amplifying element section 10 as observed from input terminal 2. It should be noted that only one film resistor 23b is illustrated in the figure as an example. The eight metal pads 23a are electrically connected to matching circuit 40 via bonding line W2.

[0050] Matching circuit 40 is disposed on the base plate 4e of package 4, positioned between branch circuit substrate 20 and amplifying element section 10 in the Y-axis direction. Matching circuit 40 is, for example, a die-capacitor, having a dielectric substrate and a circuit pattern (not shown) provided on the main surface of the dielectric substrate. The circuit pattern has multiple metal pads (not shown). The number of metal pads is, for example, set to be the same as the number of metal pads 23a. The multiple metal pads are arranged in a row along the X-axis direction. Each metal pad is electrically connected to the corresponding metal pad 23a via bonding line W2, and is electrically connected to the corresponding gate pad 14 of amplifying element section 10 via bonding line W3.

[0051] In the matching circuit 40, a T-type filter circuit is constructed based on the inductive components of the bonding lines W2 and W3, and the capacitance of the metal pads connecting the nodes between these inductive components to the reference potential (base plate 4e). The matching circuit 40 performs impedance transformation through this T-type filter circuit. Typically, the impedance in the amplifying element section 10 viewed from the gate pad 14 towards the inside of the transistor 13 is different from the characteristic impedance of the transmission line (e.g., 50Ω). The matching circuit 40 transforms this impedance to 50Ω as seen from the input terminal 2 towards the inside of the package 4 through the T-type filter circuit.

[0052] Matching circuit 50 is disposed on the base plate 4e of package 4, positioned in the Y-axis direction between amplifying element section 10 and synthesizing circuit board 30. Similar to matching circuit 40, matching circuit 50 is, for example, a parallel plate capacitor (die capacitor). Figure 2 As shown, each matching circuit 50 has a dielectric substrate 51 (see reference). Figure 2 ) and multiple matching circuit patterns 52 disposed on dielectric substrate 51 (refer to Figure 2). The dielectric substrate 51 has a rectangular shape in plan view with the X-axis direction as the long dimension direction. The thickness of the dielectric substrate 51 (the dimension in the Z-axis direction in this case) is, for example, about 200 μm. Further, the relative dielectric constant (εr) of the dielectric substrate 51 is, for example, εr = 150. Each matching circuit pattern 52 has a plurality of metal pads 53. Each metal pad 53 is electrically connected to a corresponding drain pad 15 (described later) of the amplifying element portion 10 via a bonding wire W4 (a lead wire) and is electrically connected to a corresponding metal pad 33a (described later) of the synthesis circuit substrate 30 via a bonding wire W5. Note that a more specific configuration of the matching circuit 50 will be described later.

[0053] In the matching circuit 50, a T-type filter circuit (a matching circuit) is also configured by the inductance components of the bonding wires W4 and W5 and the capacitance of the metal pads 53 between the nodes connected to these inductance components and the reference potential (the bottom plate 4e). The matching circuit 50 performs impedance conversion by the T-type filter circuit, thereby achieving impedance matching for the amplifying element portion 10. Normally, the impedance from the drain pad 15 toward the inside of the transistor 13 in the amplifying element portion 10 is different from the characteristic impedance (for example, 50 Ω) of the transmission line and is approximately a value smaller than 50 Ω. The matching circuit 50 matches this impedance to 50 Ω obtained from the output terminal 3 toward the inside of the package 4 by the T-type filter circuit.

[0054] The synthesis circuit substrate 30 is disposed on the bottom plate 4e of the package 4. The synthesis circuit substrate 30 is disposed along the Y-axis direction in parallel with the amplifying element portion 10 and the output terminal 3, between the amplifying element portion 10 and the output terminal 3. The synthesis circuit substrate 30 has a substrate 31 made of ceramic and a synthesis circuit 32 provided on a main surface of the substrate 31. The substrate 31 has, for example, a rectangular shape in plan view, with one long side 31a opposing the amplifying element portion 10 across the matching circuit 50 and the other long side 31b opposing the output terminal 3. The back surface of the substrate 31 opposes the bottom plate 4e of the package 4. One short side 31c of the substrate 31 is located near the side wall 4c of the package 4, and the other short side 31d of the substrate 31 is located near the side wall 4d of the package 4. That is, the substrate 31 extends in the X-axis direction from near one end of the package 4 to near the other end.

[0055] The combining circuit 32 combines the signals output from the plurality of drain pads 15 of the amplifying element section 10 into a single output signal. The combining circuit 32 includes a wiring pattern 33 disposed on the main surface of the substrate 31. The wiring pattern 33 has a shape that is linearly symmetrical about the centerline of the substrate 31 along the Y-axis. The wiring pattern 33 includes four metal pads 33a. The four metal pads 33a are arranged side-by-side along the long side 31a. Adjacent metal pads 33a are connected to each other via film resistors, forming Wilkinson type couplers. This ensures isolation between the plurality of drain pads 15 of the amplifying element section 10 and achieves matching of the output impedance of the amplifying element section 10 as observed from the output terminal 3. Each metal pad 33a is electrically connected to two corresponding metal pads 53 of the matching circuit 50 via bonding lines W5. The wiring pattern 33 is repeatedly coupled from the four metal pads 33a and finally reaches the connection point with the bonding line W6. The wiring pattern 33 is electrically connected to the output terminal 3 via the bonding line W6. The amplified high-frequency signal is output from the center of the substrate 31 in the X-axis direction to the output terminal 3.

[0056] Next, refer to Figure 2 The amplifying element 11 and the matching circuit 50 will be described in more detail. Figure 2 It means Figure 1 The image shows a top view of the amplifying element 11 and the matching circuit 50. The amplifying element 11 includes a semiconductor substrate 12, a plurality of transistors 13, a plurality of gate pads 14, a plurality of drain pads 15, and a plurality of source pads 16. The semiconductor substrate 12 is rectangular in shape with the X-axis as its longitudinal direction. The plurality of transistors 13 are arranged side by side on the semiconductor substrate 12 along the X-axis. The number of gate pads 14, drain pads 15, and source pads 16 is set to be the same as the number of transistors 13. Each of the plurality of gate pads 14, drain pads 15, and source pads 16 is a metal film (e.g., an Au film) formed on the main surface of the semiconductor substrate 12.

[0057] Multiple gate pads 14 are electrically connected to the gate electrodes of multiple transistors 13. The gate pads 14 are arranged side-by-side along the edge of the input terminal 2 of each amplifying element 11. Multiple drain pads 15 are electrically connected to the drain electrodes of each transistor 13. The drain pads 15 are arranged side-by-side along the edge of the output terminal 3 of each amplifying element 11. Multiple source pads 16 are electrically connected to the source electrodes of each transistor 13. The source pads 16 are arranged alternately alongside the gate pads 14 along the edge of the input terminal 2 of each amplifying element 11. Each source pad 16 is electrically connected to the base plate 4e of the package 4 via a via hole penetrating the amplifying element 11 in the thickness direction (Z-axis direction in this case) and is set to a reference potential. Each transistor 13 amplifies the high-frequency signal input to each gate pad 14 and outputs the amplified high-frequency signal from each drain pad 15.

[0058] exist Figure 2 An amplifying element 11 is shown. In this embodiment, an amplifying element 11 has a transistor group consisting of eight transistors 13. That is, in the high-frequency amplifier 1A, multiple (two in this embodiment) transistor groups are provided on the base plate 4e of the package 4. The eight transistors 13 include transistors 13A, 13B, 13C, 13D, 13E, 13F, 13G, and 13H arranged in this order in the X-axis direction. In other words, transistor 13D is arranged side by side with respect to transistor 13A in the X-axis direction, and transistors 13E, 13F, 13G, and 13H are arranged side by side with respect to transistor 13D on the opposite side of transistor 13A in the X-axis direction. Transistor 13A is an example of a first transistor in this embodiment, and transistor 13D is an example of a second transistor in this embodiment. Transistors 13E, 13F, 13G, and 13H are examples of third transistors in this embodiment. Among the eight transistors 13, transistors 13A and 13H are respectively arranged at the outermost position in the X-axis direction. Transistors 13B to 13G are arranged between transistors 13A and 13H. That is, transistors 13A and 13H are adjacent to other transistors 13 only on one side of the X-axis. In addition, transistors 13B to 13G are adjacent to other transistors 13 on both sides of the X-axis.

[0059] Hereinafter, the drain pads 15 electrically connected to the drain electrodes of transistors 13A to 13H will be referred to as drain pads 15A, 15B, 15C, 15D, 15E, 15F, 15G, and 15H, respectively. Drain pad 15A is an example of a first drain pad in this embodiment, and drain pad 15D is an example of a second drain pad in this embodiment. Drain pads 15E, 15F, 15G, and 15H are examples of third drain pads in this embodiment.

[0060] Further, the eight bonding wires W4 are respectively referred to as bonding wires W41, W42, W43, W44, W45, W46, W47, W48 corresponding to the drain pads 15A to 15H. The bonding wire W41 is one example of the first lead wire in this embodiment, and the bonding wire W44 is one example of the second lead wire in this embodiment. The bonding wires W45, W46, W47, W48 are one example of the third lead wire in this embodiment. The lengths of the eight bonding wires W4 are equal to each other. Of the eight bonding wires W4, the bonding wires W41, W48 are respectively arranged at the outermost portions in the X-axis direction. Further, the bonding wires W42 to W47 are arranged between the bonding wires W41, W48.

[0061] In this embodiment, one matching circuit 50 has two matching circuit patterns 52. Each matching circuit pattern 52 has a plurality of transmission lines 54. In the two matching circuit patterns 52, the number of the plurality of transmission lines 54 is set to be the same as the number of the transistors 13. In this embodiment, one matching circuit pattern 52 has four transmission lines 54. The four transmission lines 54 include transmission lines 54A, 54B, 54C, 54D.

[0062] The two matching circuit patterns 52 have configurations that are inverted from each other in the X-axis direction. In one matching circuit pattern 52, the transmission lines 54A, 54B, 54C, 54D are arranged in this order in the X-axis direction corresponding to the transistors 13A, 13B, 13C, 13D. The transmission line 54A in this one matching circuit pattern 52 is one example of the first transmission line in this embodiment. The transmission line 54D in this one matching circuit pattern 52 is one example of the second transmission line in this embodiment. Further, in the other matching circuit pattern 52, the transmission lines 54D, 54C, 54B, 54A are arranged in this order in the X-axis direction corresponding to the transistors 13E, 13F, 13G, 13H. The transmission lines 54D, 54C, 54B, 54A in this other matching circuit pattern 52 are one example of the third transmission line in this embodiment. Of the eight transmission lines 54, the two transmission lines 54A are respectively arranged at the outermost portions in the X-axis direction. Further, each of the transmission lines 54B, 54C, 54D is arranged between the two transmission lines 54A.

[0063] The transmission line 54A, 54B is constituted by a metal pad 53A (first pad) as the metal pad 53 described above. The transmission line 54C, 54D is constituted by a metal pad 53B (second pad) as the metal pad 53 described above. The metal pad 53A is one example of the first pad in the present embodiment. The metal pad 53B is one example of the second pad in the present embodiment. The metal pad 53A and the metal pad 53B are connected to each other via a film resistor 55a. The width (here, the maximum dimension in the X-axis direction) of the metal pad 53A and the width (here, the maximum dimension in the X-axis direction) of the metal pad 53B are equal to each other. Further, the length (here, the maximum dimension in the Y-axis direction) of the metal pad 53A and the length (here, the maximum dimension in the Y-axis direction) of the metal pad 53B are equal to each other.

[0064] Figure 3 is an enlarged view of Figure 2 one matching circuit pattern 52 in FIG. 8. One end portion of the metal pad 53A in the Y-axis direction branches into an input end 53a in the transmission line 54A and an input end 53b in the transmission line 54B. The transmission line 54A is connected to the bonding wire W41 or the bonding wire W48 at a connection point P1 (first connection point) in the input end 53a. The transmission line 54B is connected to the bonding wire W42 or the bonding wire W47 at a connection point P2 in the input end 53b. The input end 53a and the input end 53b are connected to each other via a film resistor 55b. The transmission line 54A and the transmission line 54B are coupled at a connection point Q1 in the other end portion of the metal pad 53A in the Y-axis direction, and are connected to the bonding wire W5.

[0065] Further, one end portion of the metal pad 53B in the Y-axis direction branches into an input end 53c in the transmission line 54C and an input end 53d in the transmission line 54D. The transmission line 54C is connected to the bonding wire W43 or the bonding wire W46 at a connection point P3 in the input end 53c. The transmission line 54D is connected to the bonding wire W44 or the bonding wire W45 at a connection point P4 (second connection point) in the input end 53d. The input end 53c and the input end 53d are connected to each other via a film resistor 55c. The transmission line 54C and the transmission line 54D are coupled at a connection point Q2 in the other end portion of the metal pad 53B in the Y-axis direction, and are connected to the bonding wire W5.

[0066] The outer shape of the metal pad 53A and the outer shape of the metal pad 53B are asymmetric with respect to an imaginary straight line N1 (second imaginary straight line) that is orthogonal to the imaginary straight line (first imaginary straight line) connecting the connection point P1 and the connection point P4 and passes through the midpoint of the connection point P1 and the connection point P4. In other words, the matching circuit pattern 52 has an outer shape that is asymmetric with respect to the imaginary straight line N1. With such an outer shape, the length of the portion of the outer side edge of the matching circuit pattern 52 on one side of the imaginary straight line N1 (in this case, the side including the connection point P1) is longer than the length of the portion on the other side of the imaginary straight line N1 (in this case, the side including the connection point P4). Specifically, the length of the portion on one side of the imaginary straight line N1 refers to the length of the portion of the outer side edge of the matching circuit pattern 52 including the connection point P1, from the position projected in the X-axis direction from the connection point P1 as a starting point to the position projected in the Y-axis direction from the connection point Q1 as an end point. Further, the length of the portion on the other side of the imaginary straight line N1 refers to the length of the portion of the outer side edge of the matching circuit pattern 52 including the connection point P4, from the position projected in the X-axis direction from the connection point P4 as a starting point to the position projected in the Y-axis direction from the connection point Q2 as an end point.

[0067] The metal pad 53A is substantially rectangular in plan view and has four corners. The four corners include one corner C1 (first corner) that is chamfered. Note that the three corners other than the corner C1 among the four corners are not chamfered. The metal pad 53A is connected to the metal pad 53B at one long side 53r. The corner C1 is located at the intersection of the other long side 53s in the metal pad 53A and the short side 53t opposite the synthetic circuit substrate 30 (see FIG. 1). The transmission line 54A is constituted by the portion of the metal pad 53A including the corner C1. The transmission line 54B is constituted by the portion of the metal pad 53A not including the corner C1. Figure 1 ) opposite the synthetic circuit substrate 30 (see FIG. 1). The transmission line 54A is constituted by the portion of the metal pad 53A including the corner C1. The transmission line 54B is constituted by the portion of the metal pad 53A not including the corner C1.

[0068] The metal pad 53B is substantially rectangular in plan view and has four corners. The four corners include one corner C2 (second corner) that is chamfered. The corner C2 is chamfered by a chamfer amount L2 that is larger than the chamfer amount L1 of the corner C1. The chamfer amount L2 is, for example, about three times the chamfer amount L1. Note that the three corners other than the corner C2 among the four corners are not chamfered. The metal pad 53B is connected to the metal pad 53A at one long side 53u. The corner C2 is located at the intersection of the other long side 53v in the metal pad 53B and the short side 53w opposite the synthetic circuit substrate 30 (see FIG. 1). The transmission line 54B is constituted by the portion of the metal pad 53B including the corner C2. The transmission line 54A is constituted by the portion of the metal pad 53B not including the corner C2. Figure 1) the intersection of the opposite short side 53w. The transmission line 54C is constituted by the portion of the metal pad 53B excluding the corner portion C2. The transmission line 54D is constituted by the portion of the metal pad 53B including the corner portion C2. Therefore, the length of the portion of the outer side edge of the metal pad 53B constituting the transmission line 54D is shorter than the length of the portion of the outer side edge of the metal pad 53A constituting the transmission line 54A.

[0069] Next, the electrical length in the configuration from the amplifying element 11 until reaching the combining circuit 32 is described. Figure 4 is a perspective view for describing the electrical length of each of the bonding wires W41 to W48. As shown in Figure 4 , the bonding wire W41 is mainly affected by the magnetic field coupling from the closest bonding wire W42 and the magnetic field coupling from the second closest bonding wire W43. In contrast, the bonding wire W44 is mainly affected by the magnetic field coupling from each of the closest bonding wires W43, W45 and the magnetic field coupling from each of the second closest bonding wires W42, W46. Thus, the mutual inductance component of the bonding wire W41 increases according to the influence from only one side, while the mutual inductance component of the bonding wire W44 increases according to the influence from both sides. That is, the mutual inductance component of each of the bonding wires W41 to W48 increases according to the other bonding wires W4 that are close.

[0070] Figure 5 is a Smith chart showing the impedance of each of the bonding wires W41 to W48. In Figure 5 , the S parameter (S11) of the transmission line termination corresponding to the impedance of each of the bonding wires W41 to W48 at the frequencies 10.700 GHz to 12.700 GHz is shown. Note that the impedance of each of the bonding wires W41 to W48 refers to the effective impedance of each of the bonding wires W41 to W48. The effective impedance refers to the impedance in one bonding wire W4 taking into account the influence from the other bonding wires W4. In Figure 5 , the range to be displayed is set to up to the reflection coefficient Γ = 0.3, and the impedance 50 Ω at the center of the Smith chart is normalized with the characteristic impedance Z0 = 50 Ω of the calculation port. The inductance becomes a large value in the direction of the arrow in Figure 5 , and thus it is known from Figure 5 that the inductance of the bonding wires W44, W45 is larger than the inductance of the bonding wires W41, W48.

[0071] Figure 6 is a graph showing the inductance of each of the bonding wires W41 to W48. In Figure 6 , the horizontal axis is the frequency, and the vertical axis is the value of the inductance. From Figure 6It is also known that the inductance of the bonding wires W44, W45 is larger than the inductance of the bonding wires W41, W48. Thus, in the plurality of bonding wires W4 arranged in a column, the closer to the center of the column, the larger the inductance, and the closer to the end of the column, the smaller the inductance. Therefore, in terms of the effective electrical length of the bonding wires W41 to W48, the closer to the center of the column, the longer the effective electrical length, and the closer to the end of the column, the shorter the effective electrical length. Specifically, the effective electrical length of the bonding wire W44 is longer than the effective electrical length of the bonding wire W41. Note that the effective electrical length refers to the electrical length of a prescribed path through which an electromagnetic wave passes, and refers to the electrical length in which the influence of mutual inductance from a bonding wire W4 different from the bonding wire W4 included in the path is taken into account.

[0072] Next, the electrical length of the transmission lines 54A, 54D is described. A high-frequency signal propagates in the transmission lines 54A, 54D in the form of an electromagnetic wave, and thus the electrical length of the transmission lines 54A, 54D corresponds to the length of a path through which an electromagnetic wave in the transmission lines 54A, 54D passes.

[0073] First, reference is made to Figure 7 and Figure 8 The relationship between the length of a physical path through which an electromagnetic wave passes and the phase is described. Figure 7 and Figure 8 are diagrams for describing the relationship between the length of a physical path through which an electromagnetic wave passes and the phase. In Figure 7 , a path D1 through which an electromagnetic wave E passes is shown, and in Figure 8 , a path D2 through which an electromagnetic wave E passes is shown. The path D2 is longer than the path D1. In the example of Figure 7 and Figure 8 , the length of the path D2 is about 1.4 times the length of the path D1. As a result, a phase difference occurs between the electromagnetic wave E that has passed through the path D1 and the electromagnetic wave E that has passed through the path D2. Here, the phase of the electromagnetic wave E at the terminal of the path D1 is 0 deg, and the phase of the electromagnetic wave E at the terminal of the path D2 is about 90 deg, and thus a phase difference of about 90 deg occurs.

[0074] Here, the path through which a high frequency (microwave) as an electromagnetic wave passes is described in detail. Figure 9 is a diagram for describing the distribution state of a current in a microwave. Figure 9 The (a) part of Figure 9 is a graph showing the magnitude of a current flowing in the Y-axis direction in a metal conductor 80. The metal conductor 80 is, for example, a microstrip conductor. In Figure 9In the illustrated graph, the horizontal axis is the position in the X-axis direction with the center of the metal conductor 80 in the X-axis direction as 0, and the vertical axis is the current value I.

[0075] Figure 10 is a simulation graph showing the concentration state of the current in the microwave. In Figure 10 the darker the color, the more concentrated the current. As is Figure 10 known, at both end portions in the X-axis direction of the metal conductor 80, the current is in a particularly concentrated state. Therefore, as is Figure 9 shown, it is known that, in the microwave, when the current flows in the metal conductor 80, the current value I becomes large at both end portions in the X-axis direction of the metal conductor 80.

[0076] Figure 11 is a simulation graph showing the distribution state of the electric field intensity in the microwave. In Figure 11 the darker the color, the larger the electric field intensity. As is Figure 11 known, at both end portions in the X-axis direction of the metal conductor 80, the electric field intensity becomes particularly large. Therefore, it is known that the microwave as an electromagnetic wave mainly passes from the outer edge of the pattern like the above-described metal conductor 80. In other words, the physical path through which the electromagnetic wave passes corresponds to the outer edge of the pattern. Therefore, by changing the length of the outer edge of the pattern, the length of the physical path through which the electromagnetic wave passes changes. Note that the length of the outer edge of the pattern can be changed by changing the shape of the outer edge.

[0077] Figure 12 is a plan view showing one reference example of a pattern 80A through which an electromagnetic wave passes, Figure 13 is a plan view showing another reference example of a pattern 80B through which an electromagnetic wave passes. The patterns 80A, 80B each have two input ports 81, 82 and one output port 83 in parallel. The patterns 80A, 80B each have a substantially rectangular shape, and at one end portion in the long dimension direction, are bifurcated into a portion constituting the input port 81 and a portion constituting the input port 82. The output port 83 is located at the other end portion in the long dimension direction of the patterns 80A, 80B. The distance from the input port 81 to the output port 83 is equal to the distance from the input port 82 to the output port 83.

[0078] Here, the outer shape of the pattern 80A is linearly symmetrical with respect to an imaginary straight line N82 orthogonal to an imaginary straight line N81 connecting the input ports 81, 82 and passing through the midpoints of the input ports 81, 82. In contrast, the outer shape of the pattern 80B is asymmetrical with respect to the imaginary straight line N82. In Figure 12 and Figure 13In the example, all four corners of pattern 80A are right angles, while the four corners of pattern 80B include three right angles and one chamfered corner. Specifically, the shape of pattern 80B is formed by cutting off a portion of the section from input port 81 to output port 83 from the corners that were originally right angles. Therefore, the length of the outer edge of pattern 80B from input port 81 to output port 83 is shorter than the length from input port 82 to output port 83.

[0079] As described above, microwaves, as electromagnetic waves, mainly pass through the outer edges of patterns 80A and 80B. Therefore, the path DA from input port 81 to output port 83 is shortened relative to the path DB from input port 82 to output port 83. Thus, when a difference in physical length occurs between paths DA and DB, as described above, a phase difference is generated between the electromagnetic wave passing through path DA and the electromagnetic wave passing through path DB.

[0080] Figure 14 This is a graph showing the phase difference between two electromagnetic waves that have passed through paths DA and DB, respectively, in patterns 80A and 80B. Figure 14 In the graph, the horizontal axis represents frequency, and the vertical axis represents phase difference. Figure 14 It can be seen that no phase difference is generated in pattern 80A, while a phase difference is generated in pattern 80B. Furthermore, in Figure 14 In pattern 80B, the higher the frequency, the greater the absolute value of the phase difference. Therefore, it can be seen that the higher the frequency, the greater the influence of the change in the physical length of paths DA and DB on the phase difference.

[0081] Based on the above, refer again Figure 3 The electrical lengths of transmission lines 54A and 54D in this embodiment will be explained. As described above, the length of the portion of the outer edge of the metal pad 53B that constitutes transmission line 54D is shorter than the length of the portion of the outer edge of the metal pad 53A that constitutes transmission line 54A. Therefore, the electrical length of transmission line 54D is shorter than the electrical length of transmission line 54A.

[0082] In the present embodiment, the absolute value of the electrical length difference between the transmission lines 54A, 54D is substantially equal to the absolute value of the electrical length difference between the bonding wires W41, W44 described above. Note that "substantially equal" in the present specification means to a degree that the difference between the two values is negligible. Thus, the electrical length obtained by adding the effective electrical length of the bonding wire W41 and the electrical length of the transmission line 54A is substantially equal to the electrical length obtained by adding the effective electrical length of the bonding wire W44 and the electrical length of the transmission line 54D. In other words, the effective electrical length from the drain pad 15A to the wiring pattern 33 is substantially equal to the effective electrical length from the drain pad 15D to the wiring pattern 33. In the present embodiment, the effective electrical length difference between the bonding wires W41, W44 and the electrical length difference between the transmission lines 54A, 54D cancel each other out. Thus, no phase difference is generated between the electromagnetic wave that has passed through the path from the drain pad 15A to the wiring pattern 33 and the electromagnetic wave that has passed through the path from the drain pad 15D to the wiring pattern 33.

[0083] An effect of the high-frequency amplifier 1A described above will be described. In the high-frequency amplifier 1A, each of the plurality of transistors 13 is connected to the matching circuit pattern 52 through the bonding wire W4. In this configuration, unevenness in the effective impedance can occur among the plurality of bonding wires W4 depending on the degree of influence from other bonding wires W4. Such unevenness in the effective impedance among the plurality of bonding wires W4 is manifested as unevenness in the effective electrical length among the plurality of bonding wires W4. Specifically, the effective electrical length of the bonding wire W44 becomes longer than the effective electrical length of the bonding wire W41. Here, in the high-frequency amplifier 1A, the matching circuit pattern 52 has an asymmetric outer shape, and thus the electrical length of the transmission line 54D becomes shorter than the electrical length of the transmission line 54A. Thus, in the configuration in which the effective electrical length of the bonding wire W44 is longer than the effective electrical length of the bonding wire W41, the electrical length difference between the bonding wires W41, W44 can be eliminated by the electrical length difference between the transmission lines 54A, 54D. Therefore, the unevenness between the effective electrical length from the transistor 13A (more specifically, the drain pad 15A) to the wiring pattern 33 and the effective electrical length from the transistor 13D (more specifically, the drain pad 15D) to the wiring pattern 33 is reduced. The smaller the unevenness in the electrical length among the plurality of bonding wires W4, the smaller the unevenness in the effective impedance among the plurality of bonding wires W4, and thus the unevenness in the phase among the transistors 13A, 13D can be reduced by this configuration. Note that the same applies to the transistors 13E, 13H.

[0084] In the high-frequency amplifier 1A described above, the matching circuit pattern 52 has a metal pad 53A including a corner portion C1 and a metal pad 53B including a corner portion C2. A transmission line 54A is constituted by a portion including the corner portion C1 in the metal pad 53A. A transmission line 54D is constituted by a portion including the corner portion C2 in the metal pad 53B. The corner portion C2 is chamfered with a chamfer amount L2 larger than a chamfer amount L1 of the corner portion C1. According to the insight of the present inventors and others, as described above, a current (electric field) at a high frequency easily concentrates on an outer edge of a conductor. Therefore, in the transmission line 54A, a high-frequency signal propagates along the corner portion C1 in the metal pad 53A, and in the transmission line 54D, a high-frequency signal propagates along the corner portion C2 in the metal pad 53B. Here, the corner portion C2 is chamfered with the chamfer amount L2 larger than the chamfer amount L1 of the corner portion C1, and therefore, a path including the corner portion C2 is shorter than a path including the corner portion C1, enabling a configuration in which the electrical length of the transmission line 54D is shorter than the electrical length of the transmission line 54A. Further, according to this configuration, it is easy to match the effective electrical length from the transistor 13A to the wiring pattern 33 and the effective electrical length from the transistor 13D to the wiring pattern 33 by adjustment of the chamfer amounts L1, L2. Therefore, it is possible to more reliably reduce unevenness in phase between the transistors 13A, 13D. Note that the same is true between the transistors 13E, 13H.

[0085] In the high-frequency amplifier 1A described above, a plurality of transistor groups constituted to include the transistor 13A, the transistor 13D, and the transistors 13E, 13F, 13G, 13H are provided. With this configuration, it is possible to realize a high-frequency amplifier 1A of high output.

[0086] In the high-frequency amplifier 1A described above, the bonding wire W41 is disposed at the outermost portion of the transistor group, and the bonding wire W44 is disposed between the bonding wire W41 and the bonding wires W45, W46, W47, W48. The length of the bonding wire W41 is equal to the length of the bonding wire W44, and the effective electrical length from the drain pad 15A to the wiring pattern 33 is substantially equal to the effective electrical length from the drain pad 15D to the wiring pattern 33. Therefore, the phases are substantially identical between the transistors 13A, 13D. Note that the same is true between the transistors 13E, 13H. According to the above, it is particularly advantageous from the viewpoint of improving the power efficiency of the high-frequency amplifier 1A.

[0087] Next, the high-frequency amplifier 1B of the second embodiment will be described. As described above, Figure 1is a plan view showing the internal configuration of the high-frequency amplifier 1A of the first embodiment and the high-frequency amplifier 1B of the second embodiment. The high-frequency amplifier 1B is different from the high-frequency amplifier 1A in that it is provided with the matching circuit 60 instead of the matching circuit 50, and is configured to be the same as the high-frequency amplifier 1A in other points. In the present embodiment, the high-frequency amplifier 1B is provided with two matching circuits 60 as one example. Hereinafter, points different from the high-frequency amplifier 1A will be described.

[0088] Figure 15 is a plan view showing the matching circuit 60. The matching circuit 60 is different from the matching circuit 50 in that it is provided with two matching circuit patterns 62 instead of the two matching circuit patterns 52, and is configured to be the same as the matching circuit 50 in other points. Each matching circuit pattern 62 has a plurality of metal pads 63. As with the metal pads 53, each metal pad 63 is electrically connected to a corresponding drain pad 15 of the amplifying element section 10 via a wire W4, and is electrically connected to a corresponding metal pad 33a of the synthesis circuit substrate 30 via a wire W5.

[0089] Further, the matching circuit pattern 62 has a plurality of transmission lines 64. In the two matching circuit patterns 62, the number of the plurality of transmission lines 64 is set to be the same as the number of the transistors 13 (refer to Figure 2 ). One matching circuit pattern 62 has four transmission lines 64. The four transmission lines 64 include transmission lines 64A, 64B, 64C, 64D.

[0090] The two matching circuit patterns 62 have configurations that are inverted from each other in the X-axis direction. In one matching circuit pattern 62, the transmission lines 64A, 64B, 64C, 64D are arranged in this order in the X-axis direction in correspondence with the transistors 13A, 13B, 13C, 13D (refer to Figure 2 ). The transmission line 64A in this one matching circuit pattern 62 is one example of the first transmission line in the present embodiment. The transmission line 64D in this one matching circuit pattern 62 is one example of the second transmission line in the present embodiment. Note that the transmission lines 64B, 64C in this one matching circuit pattern 62 can also be one example of the second transmission line in the present embodiment. Further, in the other matching circuit pattern 62, the transmission lines 64D, 64C, 64B, 64A are arranged in this order in the X-axis direction in correspondence with the transistors 13E, 13F, 13G, 13H. The transmission lines 64D, 64C, 64B, 64A in this other matching circuit pattern 62 are one example of the third transmission line in the present embodiment. Of the eight transmission lines 64, the two transmission lines 64A are respectively disposed at the outermost portions in the X-axis direction. Further, each of the transmission lines 64B, 64C, 64D is disposed between the two transmission lines 64A.

[0091] The transmission lines 64A, 64B are constituted by the metal pad 63A which is the metal pad 63 described above. The transmission lines 64C, 64D are constituted by the metal pad 63B which is the metal pad 63. The metal pad 63A is one example of the first pad in the present embodiment. The metal pad 63B is one example of the second pad in the present embodiment. The metal pad 63A and the metal pad 63B are connected to each other via the film resistor 65a. The width (here, the maximum dimension in the X-axis direction) of the metal pad 63A is smaller than the width (here, the maximum dimension in the X-axis direction) of the metal pad 63B. The length (here, the maximum dimension in the Y-axis direction) of the metal pad 63A is equal to the length (here, the maximum dimension in the Y-axis direction) of the metal pad 63B.

[0092] Figure 16 is an enlarged view of Figure 15 one matching circuit pattern 62 in FIG. 6. One end portion of the metal pad 63A in the Y-axis direction branches into an input end 63a in the transmission line 64A and an input end 63b in the transmission line 64B. The transmission line 64A is connected to the bonding wire W41 or the bonding wire W48 at a connection point P5 (first connection point) in the input end 63a. The transmission line 64B is connected to the bonding wire W42 or the bonding wire W47 at a connection point P6 in the input end 63b. The input end 63a and the input end 63b are connected to each other via the film resistor 65b. The transmission line 64A and the transmission line 64B are coupled at a connection point Q3 in the other end portion of the metal pad 63A in the Y-axis direction, and are connected to the bonding wire W5.

[0093] In addition, one end portion of the metal pad 63B in the Y-axis direction branches into an input end 63c in the transmission line 64C and an input end 63d in the transmission line 64D. The transmission line 64C is connected to the bonding wire W43 or the bonding wire W46 at a connection point P7 in the input end 63c. The transmission line 64D is connected to the bonding wire W44 or the bonding wire W45 at a connection point P8 (second connection point) in the input end 63d. The input end 63c and the input end 63d are connected to each other via the film resistor 65c. The transmission line 64C and the transmission line 64D are coupled at a connection point Q4 in the other end portion of the metal pad 63B in the Y-axis direction, and are connected to the bonding wire W5.

[0094] The shapes of metal pads 63A and 63B are asymmetrical about an imaginary line N2 (the second imaginary line), wherein the imaginary line N2 is orthogonal to the imaginary line (the first imaginary line) connecting connection points P5 and P8, and passes through the midpoint between connection points P5 and P8. In other words, the matching circuit pattern 62 has an asymmetrical shape about the imaginary line N2. With this shape, the length of the portion of the outer edge of the matching circuit pattern 62 on one side of the imaginary line N2 (here, the side including connection point P5) is longer than the length of the portion on the other side of the imaginary line N2 (here, the side including connection point P8). Specifically, the length of the portion on one side of the imaginary line N2 refers to the length of the portion of the outer edge of the matching circuit pattern 62 including metal pads 63A, starting from the position projected from connection point P5 in the X-axis direction and ending at the position projected from connection point Q3 in the Y-axis direction. Furthermore, the length of the portion on the other side of the imaginary straight line N2 refers to the length of the portion of the outer edge of the matching circuit pattern 62, including the metal pad 63B, that starts from the position projected from the connection point P8 in the X-axis direction and ends at the position projected from the connection point Q4 in the Y-axis direction.

[0095] Similar to metal pad 53A, metal pad 63A is generally rectangular when viewed from above, having four corners including a corner C1 (first corner). Metal pad 63A is connected to metal pad 63B at one long side 63r. Corner C1 is located on another long side 63s of metal pad 63A and is integrated with the circuit board 30 (see reference). Figure 1 The intersection of the opposite short sides 63t. Transmission line 64A is formed by the portion of metal pad 63A including corner C1. Transmission line 64B is formed by the portion of metal pad 63A excluding corner C1.

[0096] Similar to metal pad 53B, metal pad 63B is generally rectangular when viewed from above, having four corners including a corner C2 (second corner). Metal pad 63B is connected to metal pad 63A at one long side 63u. Corner C2 is located on another long side 63v of metal pad 63B and is integrated with the circuit board 30 (see reference). Figure 1 The intersection of the opposite short sides 63w. Transmission line 64C is formed by the portion of metal pad 63B excluding corner C2. Transmission line 64D is formed by the portion of metal pad 63B including corner C2.

[0097] In the present embodiment, the length of the portion of the outer edge of the metal pad 63B that constitutes the transmission line 64D is shorter than the length of the portion of the outer edge of the metal pad 63A that constitutes the transmission line 64A. As one example, in the metal pad 63A, the length L3 of the long side 63s is about 485 μm, the length L4 of the short side 63t is about 325 μm, and the length L5 of the chamfer portion at the corner C1 is about 78 μm. The length of the portion of the outer edge of the metal pad 63A that constitutes the transmission line 64A (i.e., the total of the lengths L3, L4, and L5) is about 888 μm in this case. Further, in the metal pad 63B, the length L6 of the long side 63v is about 360 μm, the length L7 of the short side 63w is about 255 μm, and the length L8 of the chamfer portion at the corner C2 is 255 μm. The length of the portion of the outer edge of the metal pad 63B that constitutes the transmission line 64D (i.e., the total of the lengths L6, L7, and L8) is about 870 μm in this case.

[0098] Further, the metal pad 63A has an asymmetric outer shape with respect to an imaginary straight line N3 (second imaginary straight line) that is orthogonal to the imaginary straight line (first imaginary straight line) that connects the connection point P5 and the connection point P6 and passes through the midpoint of the connection point P5 and the connection point P6. Further, the metal pad 63B has an asymmetric outer shape with respect to an imaginary straight line N4 (second imaginary straight line) that is orthogonal to the imaginary straight line (first imaginary straight line) that connects the connection point P7 and the connection point P8 and passes through the midpoint of the connection point P7 and the connection point P8. Specifically, the width L11 of the input end 63a (dimension in the X-axis direction in this case) is different from the width L12 of the input end 63b (dimension in the X-axis direction in this case), and the width L13 of the input end 63c (dimension in the X-axis direction in this case) is different from the width L14 of the input end 63d (dimension in the X-axis direction in this case). The width L11 is smaller than the width L12. That is, the transmission line 64A is thinner than the transmission line 64B. Further, the width L13 is smaller than the width L14. That is, the transmission line 64C is thinner than the transmission line 64D.

[0099] In the present embodiment, the transmission lines 64A, 64B are thinner than the transmission lines 64C, 64D. The widths L11, L12, L13, L14 are different from each other and increase in this order. In other words, among the plurality of input terminals arranged in the X-axis direction, the input terminal closer to the center in the X-axis direction of the dielectric substrate 51 has a larger width (in this case, the dimension in the X-axis direction). For example, the width L11 is about 0.6 times the width L14, the width L12 is about 0.85 times the width L14, and the width L13 is about 0.9 times the width L14. As one example, the width L11 is about 120 μm, the width L12 is about 170 μm, the width L13 is about 180 μm, and the width L14 is about 200 μm. In this example, if the thickness (specifically, 200 μm) and the relative permittivity (specifically, εr = 150) of the dielectric substrate 51 described above are taken into account, the effective wavelength in the transmission line 64A becomes 123.4 deg and the effective wavelength in the transmission line 64D becomes 120.9 deg in the case where the frequency is 11.7 GHz.

[0100] The electrical lengths of the transmission lines 64A, 64D will be described. As described above, the length of the portion of the outer edge of the metal pad 63B that constitutes the transmission line 64D is shorter than the length of the portion of the outer edge of the metal pad 63A that constitutes the transmission line 64A. Also, in the present embodiment, the transmission line 64A is thinner than the transmission line 64D, and thus the impedance of the transmission line 64A is larger than the impedance of the transmission line 64D. Therefore, the electrical length of the transmission line 64D is shorter than the electrical length of the transmission line 64A.

[0101] In the present embodiment, the absolute value of the difference in the electrical lengths between the transmission lines 64A, 64D is equal to the absolute value of the effective difference in the electrical lengths between the wires W41, W44 described above, for example. Thus, the electrical length obtained by adding the effective electrical length of the wire W41 and the electrical length of the transmission line 64A is substantially equal to the electrical length obtained by adding the effective electrical length of the wire W44 and the electrical length of the transmission line 64D. In other words, the effective electrical length from the drain pad 15A to the wiring pattern 33 is substantially equal to the effective electrical length from the drain pad 15D to the wiring pattern 33. In the present embodiment, the effective difference in the electrical lengths between the wires W41, W44 and the difference in the electrical lengths between the transmission lines 64A, 64D cancel each other out. Thus, no phase difference is generated between the electromagnetic wave that has passed through the path from the drain pad 15A to the wiring pattern 33 and the electromagnetic wave that has passed through the path from the drain pad 15D to the wiring pattern 33.

[0102] The effect of the high-frequency amplifier 1B described above will be described. First, the comparative example will be described. The high-frequency amplifier of the comparative example differs from the high-frequency amplifier 1B in that the matching circuit 60X of the comparative example is provided instead of the matching circuit 60. Figure 19 is a plan view showing the matching circuit 60X of the high-frequency amplifier of the comparative example. The matching circuit 60X differs from the matching circuit 60 in that two matching circuit patterns 62X are provided instead of the two matching circuit patterns 62, and is configured to be the same as the matching circuit 60 in other points.

[0103] Each matching circuit pattern 62X has two metal pads 63X instead of the metal pads 63A, 63B. The metal pads 63X differ from the metal pads 63A, 63B in that the corners C1, C2 are not chamfered. In the metal pads 63X, all of the four corners are configured to be right angles. Further, the two metal pads 63X in the matching circuit pattern 62X differ from the metal pads 63A, 63B in that four input terminals 63y are provided instead of the input terminals 63a, 63b, 63c, 63d. The widths (dimensions in the X-axis direction here) of the four input terminals 63y are equal to each other. The metal pads 63X are configured to be the same as the metal pads 63A, 63B in other points. That is, the outline of the matching circuit pattern 62X of the comparative example is line-symmetrical about the imaginary straight line N2.

[0104] Figure 20 is a Smith chart showing each load impedance in the transistors 13A, 13B, 13C, 13D of the high-frequency amplifier of the comparative example. In Figure 20 , each load impedance in the transistors 13A, 13B, 13C, 13D is shown between the frequencies 10.700 GHz and 12.700 GHz. From Figure 20 , it is known that the range of the unevenness of the phase (here, the phase difference ΔZ1 between the transistors 13A, 13D) generated among the transistors 13A, 13B, 13C, 13D becomes large. In Figure 20 , the phase difference ΔZ1 is about 9 deg.

[0105] It is to be noted that it is considered that each load impedance in the transistors 13H, 13G, 13F, 13E is the same degree as each load impedance in the transistors 13A, 13B, 13C, 13D. From the above, it is known that in the high-frequency amplifier of the comparative example, a large unevenness (an unevenness in the range of about 9 deg. in the example of Figure 20 ) in the phase is generated among the transistors 13A to the transistor 13H.

[0106] Figure 21 is a graph showing the relationship between the unevenness of the phase of the load impedance and the power efficiency in the comparative example. In Figure 21The contour map shows that the darker the color, the greater the power efficiency. Furthermore, in... Figure 21 The Smith chart shows the peak point Z10 of the phase of the load impedance at a frequency of 11.700 GHz, where the maximum power efficiency (ηd = 52.9%) is achieved. The peak point Z10 is 99 degrees here. Figure 21 It can be seen that the power efficiency at point Z11 (108 degrees in this case), which is approximately 9 degrees off from the peak point Z10, is lower than that at the peak point Z10 (here, ηd = approximately 50.0%). Therefore, it can be concluded that with the use of the matching circuit 60X, the power efficiency decreases by approximately 3% compared to the peak point Z10.

[0107] In contrast, the high-frequency amplifier 1B according to this embodiment, with the same configuration as the high-frequency amplifier 1A described above, can achieve the same effect as the high-frequency amplifier 1A. Furthermore, in the high-frequency amplifier 1B, the transmission line 64A is thinner than the transmission line 64D. This allows the impedance per unit length of the transmission line 64A to be greater than the impedance per unit length of the transmission line 64D, thus enabling a configuration where the electrical length of the transmission line 64D is shorter than the electrical length of the transmission line 64A. Moreover, the effective electrical length from transistor 13A to wiring pattern 33 can be easily matched with the effective electrical length from transistor 13D to wiring pattern 33 by adjusting the thinning of the transmission line 64A. Therefore, phase unevenness between transistor 13A and transistor 13D can be reduced more reliably. For the same reason, phase unevenness between transistor 13A and transistor 13H can be reduced more reliably.

[0108] Figure 17 This is a Smith chart showing the load impedances of transistors 13A, 13B, 13C, and 13D in the high-frequency amplifier 1B of the second embodiment. Figure 17 The image shows the load impedances of transistors 13A, 13B, 13C, and 13D between frequencies of 10.700 GHz and 12.700 GHz. Figure 17 It can be seen that the range of phase unevenness generated among transistors 13A, 13B, 13C, and 13D (in this case, the phase difference ΔZ2 generated between transistors 13A and 13D) is small. Figure 17 In the example, the phase difference ΔZ2 is approximately 4 degrees.

[0109] It should be noted that the load impedances of transistors 13H, 13G, 13F, and 13E can be considered to be to the same extent as the load impedances of transistors 13A, 13B, 13C, and 13D. From the above, it can be seen that, according to high-frequency amplifier 1B, only a small phase imbalance is generated between transistors 13A and 13H (in... Figure 17about 4 deg in the example of FIG. 6). It is thus known that the high-frequency amplifier IB can reduce the unevenness of the phase generated between the transistors 13A to 13H, as compared with the high-frequency amplifier of the comparative example. In Figure 17 It is known that the range of the unevenness can be reduced by about 5 deg in the example of FIG. 6, as compared with Figure 20

[0110] Figure 18 is a graph showing the relationship between the unevenness of the phase of the load impedance and the power efficiency in the second embodiment. In the contour map of Figure 18 the part where the color is darker, the power efficiency is greater. Further, in Figure 18 the same as in Figure 21 the peak point Z10 is shown. It is known from Figure 18 that the point Z12 (103 deg in this case) where the phase is shifted by about 4 deg from the peak point Z10 is the power efficiency (ηd = about 52.1% in this case) that is approximately equivalent to the peak point Z10. It is thus known that the use of the matching circuit 60 can suppress the decrease in the power efficiency with respect to the peak point Z10 to less than 1%.

[0111] The above embodiments have described one embodiment of the high-frequency amplifier of the present disclosure. The high-frequency amplifier of the present disclosure can employ a high-frequency amplifier that is arbitrarily changed from each of the above-described embodiments.

[0112] For example, the high-frequency amplifier IA of the above-described embodiments has two matching circuits 40, 50 each, and the amplifying element section 10 includes two amplifying elements 11, but is not limited to this configuration. The high-frequency amplifier IA can have one matching circuit 40, 50 each, and can have three or more matching circuits 40, 50 each. The amplifying element section 10 can include a single amplifying element 11, and can include three or more amplifying elements 11. The same applies to the high-frequency amplifier IB. Further, the high-frequency amplifiers IA, IB can have the matching circuit 50 or the matching circuit 60 instead of the matching circuit 40, respectively.

[0113] Further, the number of the transistors 13 and the number of the bonding wires W4 are arbitrary, and can be less than eight or can be nine or more. The number of the matching circuit patterns 52, 62 and the number of the transmission lines 54, 64 can be arbitrarily changed in correspondence with the number of the transistors 13 and the number of the bonding wires W4.

[0114] ​Further, in the above-described embodiment, the matching circuit pattern 52 has two metal pads 53, but is not limited to this configuration. The matching circuit pattern 52 can have only one metal pad 53, and can have three or more metal pads 53. Further, the matching circuit pattern 52 can have both the metal pads 53 and 63. The same applies to the matching circuit pattern 62.

[0115] Reference Signs

[0116] 1A, 1B: high-frequency amplifier

[0117] 2: input terminal

[0118] 3: output terminal

[0119] 4: package

[0120] 4a, 4b: end wall

[0121] 4c, 4d: side wall

[0122] 4e: bottom plate

[0123] 10: amplifying element portion

[0124] 11: amplifying element

[0125] 12: semiconductor substrate

[0126] 13, 13B, 13C: transistor

[0127] 13A: transistor (first transistor)

[0128] 13D: transistor (second transistor)

[0129] 13E, 13F, 13G, 13H: transistor (third transistor)

[0130] 14: gate pad

[0131] 15, 15B, 15C: drain pad

[0132] 15A: drain pad (first drain pad)

[0133] 15D: drain pad (second drain pad)

[0134] 15E, 15F, 15G, 15H: drain pad (third drain pad)

[0135] 16: source pad

[0136] 20: branch circuit substrate

[0137] 21: substrate

[0138] 21a, 21b: long side

[0139] 21c, 21d: short side

[0140] 22: branch circuit

[0141] 23: wiring pattern

[0142] 23a: metal pad

[0143] 23b: film resistor

[0144] 30: synthetic circuit substrate

[0145] 31: substrate

[0146] 31a, 31b: long side

[0147] 31c, 31d: short side

[0148] 32: synthetic circuit

[0149] 33: wiring pattern

[0150] 33a: metal pad

[0151] 40: matching circuit

[0152] 50: matching circuit

[0153] 51: dielectric substrate

[0154] 52: matching circuit pattern

[0155] 53: metal pad

[0156] 53A: metal pad (first pad)

[0157] 53B: metal pad (second pad)

[0158] 53a, 53b, 53c, 53d: input terminal

[0159] 53r, 53s, 53u, 53v: long side

[0160] 53t, 53w: short side

[0161] 54, 54B, 54C: transmission line

[0162] 54A: transmission line (first transmission line)

[0163] 54D: transmission line (second transmission line)

[0164] 55a, 55b, 55c: film resistor

[0165] 60, 60X: matching circuit

[0166] 62, 62X: matching circuit pattern

[0167] 63A: metal pad (first pad)

[0168] 63B: metal pad (second pad)

[0169] 63X: metal pad

[0170] 63a, 63b, 63c, 63d, 63y: input terminal

[0171] 63r, 63s, 63u, 63v: long side

[0172] 63t, 63w: short side

[0173] 64, 64B, 64C: transmission line

[0174] 64A: transmission line (first transmission line)

[0175] 64D: transmission line (second transmission line)

[0176] 65a, 65b, 65c: film resistor

[0177] 80: metal conductor

[0178] 80A, 80B: pattern

[0179] 81, 82: input port

[0180] 83: output port

[0181] 90: dielectric substrate

[0182] C1: corner (first corner)

[0183] C2: corner (second corner)

[0184] E: electromagnetic wave

[0185] D1, D2: path

[0186] I: current value

[0187] L1, L2: chamfer amount

[0188] L11, L12, L13, L14: width

[0189] N1, N2, N3, N4: imaginary straight line (second imaginary straight line)

[0190] N81, N82: imaginary straight line

[0191] P1, P5: connection point (first connection point)

[0192] P4, P8: connection points (second connection points)

[0193] P2, P3, P6, P7: connection points

[0194] Q1, Q2, Q3, Q4: connection points

[0195] W1, W2, W3, W5, W6: bonding wires

[0196] W4, W42, W43: bonding wires (lead wires)

[0197] W41: bonding wire (first lead wire)

[0198] W44: bonding wire (second lead wire)

[0199] W45, W46, W47, W48: bonding wires (third lead wires)

[0200] Z10: peak point

[0201] Z11, Z12: points

[0202] ΔZ1, ΔZ2: phase difference

Claims

1. A high-frequency amplifier comprising: a first transistor, a second transistor arranged side by side with the first transistor in a first direction, and a third transistor arranged side by side with the second transistor in the first direction on a side opposite to the first transistor; a first drain pad electrically connected to a drain electrode of the first transistor, a second drain pad electrically connected to a drain electrode of the second transistor, and a third drain pad electrically connected to a drain electrode of the third transistor; a matching circuit pattern having a first transmission line electrically connected to the first drain pad, a second transmission line electrically connected to the second drain pad, and a third transmission line electrically connected to the third drain pad, for performing impedance matching for a high-frequency signal of each of the first transistor, the second transistor, and the third transistor; a first lead electrically connecting the first transmission line and the first drain pad, a second lead electrically connecting the second transmission line and the second drain pad, and a third lead electrically connecting the third transmission line and the third drain pad; and a wiring pattern electrically connected to the first drain pad via the first transmission line and the first lead, and electrically connected to the second drain pad via the second transmission line and the second lead, an effective impedance of the second lead being greater than an effective impedance of the first lead, the matching circuit pattern having an asymmetric shape with respect to a second imaginary straight line orthogonal to a first imaginary straight line connecting a first connection point of the first transmission line connecting the first lead and a second connection point of the second transmission line connecting the second lead, and passing through a midpoint of the first connection point and the second connection point, an electrical length of the second transmission line being shorter than an electrical length of the first transmission line.

2. The high-frequency amplifier according to claim 1, wherein the matching circuit pattern has a first pad including a first corner and a second pad including a second corner, the first transmission line is constituted by a portion of the first pad including the first corner, the second transmission line is constituted by a portion of the second pad including the second corner, and the second corner is chamfered at a chamfer amount greater than a chamfer amount of the first corner.

3. The high-frequency amplifier according to claim 1 or 2, wherein the first transmission line is thinner than the second transmission line.

4. The high-frequency amplifier according to any one of claims 1 to 3, provided with a plurality of transistor groups each constituted by the first transistor, the second transistor, and the third transistor.

5. The high-frequency amplifier according to claim 4, wherein the first lead is arranged at an outermost portion of the transistor groups, and the second lead is arranged between the third lead and the first lead, a length of the first lead is equal to a length of the second lead, and an effective electrical length from the first drain pad to the wiring pattern is substantially equal to an effective electrical length from the second drain pad to the wiring pattern. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images