High frequency circuit

Abstract

To provide a high frequency circuit having high transmission efficiency.SOLUTION: A high frequency circuit according to an embodiment includes: a first substrate part having a first substrate that has a first surface facing a first direction and a first side surface facing a second direction orthogonal to the first direction; a transmission line provided on the first surface; a second substrate part having a second substrate provided side by side with the first substrate in the second direction at a predetermined interval and having a second surface facing the first direction, and a surface conductive part provided on the second surface; and a boning wire connecting the transmission line with the surface conductive part. The first substrate part includes a first side surface conductive part provided on the first side surface and capacitively coupled to the transmission line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments relate to a high frequency circuit, for example, to a grounding structure of a high frequency circuit. [Background technology]

[0002] High-frequency circuits are used in wireless communication devices and radar equipment. High-frequency circuits have transmission lines provided on a substrate. In such high-frequency circuits, two substrates may be connected via bonding wires. For example, transmission lines may be connected to each other, or a semiconductor chip may be connected to a transmission line via bonding wires. While mismatch loss is minimized by keeping the gap between the substrates as narrow as possible, a certain gap is required due to the processing accuracy of the substrates and the mounting requirements. When connecting two substrates via bonding wires in high-frequency circuits, it is desirable to reduce mismatch loss between the substrates and improve transmission efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-77902 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of an embodiment of the present invention is to provide a high-frequency circuit with high transmission efficiency. [Means for solving the problem]

[0005] The high-frequency circuit according to the embodiment comprises a first substrate unit having a first substrate having a first surface facing a first direction and a first side surface facing a second direction perpendicular to the first direction, and a transmission line provided on the first surface; a second substrate unit arranged next to the first substrate in the second direction at a predetermined interval, and having a second surface facing the first direction and a surface conductive portion provided on the second surface; and a bonding wire connecting the transmission line and the surface conductive portion, wherein the first substrate unit has a first side surface conductive portion provided on the first side surface and capacitively coupled to the transmission line. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a perspective view schematically illustrating a high-frequency circuit according to an embodiment. [Figure 2] 1 is a cross-sectional view schematically illustrating a high-frequency circuit according to an embodiment. [Figure 3] FIG. 1 is a plan view schematically illustrating a high-frequency circuit according to an embodiment. [Figure 4] FIG. 2 is a circuit diagram schematically illustrating an equivalent circuit of the high-frequency circuit according to the embodiment. [Figure 5] 10 is a graph schematically showing an example of a simulation result of the high-frequency circuit according to the embodiment. [Figure 6] 10 is a graph schematically showing an example of a simulation result of a reference high-frequency circuit. [Figure 7] 7(a) to 7(c) are cross-sectional views that schematically show an example of a method for manufacturing a high-frequency circuit according to an embodiment. [Figure 8] FIG. 10 is a plan view schematically illustrating a modified example of the high-frequency circuit according to the embodiment. [Figure 9] FIG. 10 is a plan view schematically illustrating a modified example of the high-frequency circuit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0008] FIG. 1 is a perspective view schematically illustrating a high-frequency circuit according to an embodiment. FIG. 2 is a cross-sectional view schematically illustrating the high-frequency circuit according to the embodiment. FIG. 2 is a schematic cross section taken along line A1-A2 in FIG. 1 and 2, the high-frequency circuit 10 includes a first substrate portion 11, a second substrate portion 12, and bonding wires 14. The high-frequency circuit 10 is used in high-frequency circuits such as wireless communication devices, radar devices, and high-frequency amplifiers, for example.

[0009] The first substrate unit 11 has a first substrate 21 and a first transmission line 31 (transmission line). The first substrate 21 has a first surface 21a facing a first direction and a first side surface 21b facing a second direction perpendicular to the first direction. The first substrate 21 also has, for example, a first back surface 21c facing a direction opposite to the first direction. In other words, the first back surface 21c is a surface facing a direction opposite to the first surface 21a.

[0010] The first direction is, for example, the +Z direction. The direction opposite to the first direction is, for example, the -Z direction. The second direction is, for example, the +X direction. The first surface 21a is not limited to a surface perpendicular to the +Z direction, but may be any surface having at least a component facing the +Z direction. The first surface 21a may be, for example, a surface inclined with respect to the +Z direction. The same applies to other surfaces such as the first side surface 21b and the first back surface 21c. The first side surface 21b may be any surface having at least a component facing the +X direction. The first back surface 21c may be any surface having at least a component facing the -Z direction.

[0011] The first substrate 21 has insulating properties. The first substrate 21 is, for example, a dielectric substrate having a higher dielectric constant than air. For example, a ceramic material or a resin material is used for the first substrate 21. The material of the first substrate 21 is not limited to these, and any insulating material may be used.

[0012] The first substrate 21 is, for example, in the shape of a substantially rectangular plate, but the shape of the first substrate 21 is not limited to this and may be any shape that has at least a first surface 21a and a first side surface 21b.

[0013] The first transmission line 31 is provided on the first surface 21a of the first substrate 21. The first transmission line 31 transmits a high-frequency signal. The frequency of the high-frequency signal transmitted by the first transmission line 31 is DC to 40 GHz or higher. In other words, the high-frequency signal transmitted by the first transmission line 31 is a microwave or millimeter-wave signal. The first transmission line 31 is, for example, a microstrip line having a characteristic impedance of 50 Ω. The first transmission line 31 is conductive. The conductivity of the first transmission line 31 is higher than the conductivity of the first substrate 21. The first transmission line 31 is made of a metal material such as gold or copper. However, the material of the first transmission line 31 is not limited to these and may be any material that can appropriately transmit a high-frequency signal.

[0014] The first substrate unit 11 further has, for example, a first back surface conductive portion 41 provided on the first back surface 21c. The first back surface conductive portion 41 is provided, for example, on the entire surface of the first back surface 21c. Like the first transmission line 31, the first back surface conductive portion 41 is made of a metal material such as gold or copper.

[0015] The second substrate unit 12 has a second substrate 22 and a second transmission line 32 (surface conductive portion). The second substrate 22 is arranged next to the first substrate 21 at a predetermined distance in the second direction (+X direction). The second substrate 22 has a second surface 22a facing the first direction (+Z direction).

[0016] The second substrate 22 further has, for example, a second side surface 22b facing in the direction opposite to the second direction and a second back surface 22c facing in the direction opposite to the first direction. The direction opposite to the second direction is, for example, the -X direction.

[0017] For example, the second side surface 22b of the second substrate 22 faces the first side surface 21b of the first substrate 21. More specifically, the second substrate 22 faces at least a portion of the second side surface 22b with at least a portion of the first side surface 21b.

[0018] The second substrate 22 is, for example, in the form of a substantially rectangular plate. However, the shape of the second substrate 22 is not limited to this and may be any shape having at least the second surface 22a. The material of the second substrate 22 can be the same as that of the first substrate 21, and therefore a detailed description thereof will be omitted.

[0019] The second transmission line 32 is provided on the second surface 22a of the second substrate 22. The second transmission line 32 is a microstrip line having a characteristic impedance of, for example, 50 Ω, similar to the first transmission line 31. The material of the second transmission line 32 can be the same as the material of the first transmission line 31, and therefore a detailed description thereof will be omitted.

[0020] The second substrate portion 12 further includes, for example, a second back surface conductive portion 42 provided on the second back surface 22 c. The second back surface conductive portion 42 is provided, for example, on the entire surface of the second back surface 22 c. The second back surface conductive portion 42 is made of, for example, a metal material such as gold or copper.

[0021] The bonding wire 14 connects the first transmission line 31 and the second transmission line 32. The bonding wire 14 is conductive and electrically connects the first transmission line 31 and the second transmission line 32. The bonding wire 14 is made of a metal material such as gold or copper.

[0022] In this example, the high frequency circuit 10 has two bonding wires 14. However, the number of bonding wires 14 provided in the high frequency circuit 10 is not limited to two, and may be one, or three or more.

[0023] The high-frequency circuit 10 further includes a conductor 16. The first substrate unit 11 and the second substrate unit 12 are arranged side by side on the conductor 16. The conductor 16 is set to a ground potential. The first substrate unit 11 is soldered onto the conductor 16, and the first back surface conductive unit 41 is in contact with the conductor 16. In other words, the first back surface conductive unit 41 is electrically connected to the conductor 16. Similarly, the second substrate unit 12 is soldered onto the conductor 16, and the second back surface conductive unit 42 is in contact with the conductor 16. The second back surface conductive unit 42 is electrically connected to the conductor 16. As a result, the potentials of the first back surface conductive unit 41 and the second back surface conductive unit 42 are also set to a ground potential.

[0024] In this way, the first back surface conductive portion 41 and the second back surface conductive portion 42 are set to the ground potential via the conductor 16. However, the method for setting the first back surface conductive portion 41 and the second back surface conductive portion 42 to the ground potential is not limited to the method via the conductor 16, and any method that can appropriately set the first back surface conductive portion 41 and the second back surface conductive portion 42 to the ground potential may be used.

[0025] The first substrate unit 11 further has a first side surface conductive portion 51 that is provided on the first side surface 21b and capacitively coupled to the first transmission line 31. The first side surface conductive portion 51 is set to the ground potential. In other words, the first substrate unit 11 sets the potential of the first side surface conductive portion 51 to the ground potential. This causes a capacitive component between the first side surface conductive portion 51 and the first transmission line 31.

[0026] The first side surface conductive portion 51 is electrically connected to the first back surface conductive portion 41. In other words, the first side surface conductive portion 51 is electrically connected to the conductor 16. The first side surface conductive portion 51 is in contact with the first back surface conductive portion 41, for example. The first side surface conductive portion 51 is provided integrally with the first back surface conductive portion 41, for example. In other words, the first side surface conductive portion 51 is provided contiguous with the first back surface conductive portion 41. This allows the potential of the first side surface conductive portion 51 to be set to the ground potential via the first back surface conductive portion 41. In this way, the first substrate portion 11 electrically connects the first side surface conductive portion 51 to the first back surface conductive portion 41, thereby setting the potential of the first side surface conductive portion 51 to the ground potential.

[0027] However, the method for setting the potential of the first side surface conductive portion 51 to the ground potential is not limited to the above, and any method that can appropriately set the potential of the first side surface conductive portion 51 to the ground potential may be used. For example, the potential of the first side surface conductive portion 51 may be set to the ground potential by bringing the first side surface conductive portion 51 into contact with the conductor 16.

[0028] The second substrate portion 12 further includes a second side surface conductive portion 52 that is provided on the second side surface 22b and capacitively coupled to the second transmission line 32. The second side surface conductive portion 52 is set to the ground potential. This causes a capacitive component between the second side surface conductive portion 52 and the second transmission line 32.

[0029] The second side surface conductive portion 52 is electrically connected to the second back surface conductive portion 42. In other words, the second side surface conductive portion 52 is electrically connected to the conductor 16. The second side surface conductive portion 52 is in contact with the second back surface conductive portion 42, for example. The second side surface conductive portion 52 is provided integrally with the second back surface conductive portion 42, for example. In other words, the second side surface conductive portion 52 is provided contiguous with the second back surface conductive portion 42. This allows the potential of the second side surface conductive portion 52 to be set to the ground potential via the second back surface conductive portion 42.

[0030] However, similar to the first side surface conductive portion 51, the method for setting the potential of the second side surface conductive portion 52 to the ground potential is not limited to the above, and any method that can appropriately set the potential of the second side surface conductive portion 52 to the ground potential may be used.

[0031] The first side surface conductive portion 51 and the second side surface conductive portion 52 are made of, for example, a metal material such as gold or copper. The material of the first side surface conductive portion 51 is, for example, the same as the material of the first back surface conductive portion 41. The material of the second side surface conductive portion 52 is, for example, the same as the material of the second back surface conductive portion 42. However, the material of the first side surface conductive portion 51 may be different from the material of the first back surface conductive portion 41. The material of the second side surface conductive portion 52 may be different from the material of the second back surface conductive portion 42.

[0032] FIG. 3 is a plan view schematically illustrating the high-frequency circuit according to the embodiment. As shown in FIGS. 1 and 3, the first transmission line 31 has a first end portion 31a (end portion) provided at one end in the second direction (+X direction), and a first line portion 31b (line portion) extending from the first end portion 31a in a direction opposite to the second direction (-X direction).

[0033] The length L11 of the first end 31a in a third direction perpendicular to each of the first and second directions is longer than the length L12 of the first line portion 31b in the third direction. The third direction is, for example, the +Y direction or the −Y direction. The length L11 of the first end 31a in the third direction and the length L12 of the first line portion 31b in the third direction are, in other words, the width of the first end 31a in the third direction and the width of the first line portion 31b in the third direction.

[0034] The second transmission line 32 has a second end 32a provided at one end in the direction opposite to the second direction (-X direction) and a second line portion 32b extending from the second end 32a in the second direction (+X direction). The length L21 of the second end 32a in the third direction is longer than the length L22 of the second line portion 32b in the third direction.

[0035] The position in the third direction of at least a portion of the first side surface conductive portion 51 is the same as the position in the third direction of at least a portion of the first transmission line 31. The position in the third direction of at least a portion of the first side surface conductive portion 51 is the same as the position in the third direction of at least a portion of the first end portion 31a, for example. The first side surface conductive portion 51 is disposed at a distance from the first transmission line 31 in the first and second directions. In other words, the first side surface conductive portion 51 is not in contact with the first transmission line 31. As a result, the first side surface conductive portion 51 is capacitively coupled to the first transmission line 31. The first side surface conductive portion 51 is capacitively coupled to, for example, the first end portion 31a.

[0036] Similarly, the position in the third direction of at least a portion of the second side surface conductive portion 52 is the same as the position in the third direction of at least a portion of the second transmission line 32. The position in the third direction of at least a portion of the second side surface conductive portion 52 is the same as the position in the third direction of at least a portion of the second end portion 32a, for example. The second side surface conductive portion 52 is disposed at a distance from the second transmission line 32 in the first direction and the second direction. In other words, the second side surface conductive portion 52 is not in contact with the second transmission line 32. As a result, the second side surface conductive portion 52 is capacitively coupled to the second transmission line 32. The second side surface conductive portion 52 is capacitively coupled to, for example, the second end portion 32a.

[0037] The length in the third direction of the first side surface conductive portion 51 is set to, for example, approximately the same as the length L11 of the first end portion 31a in the third direction. The length in the third direction of the first side surface conductive portion 51 is set to, for example, 0.5 to 1.5 times the length L11 of the first end portion 31a in the third direction. The length in the third direction of the second side surface conductive portion 52 is set to, for example, approximately the same as the length L21 of the second end portion 32a in the third direction. The length in the third direction of the second side surface conductive portion 52 is set to, for example, 0.5 to 1.5 times the length L21 of the second end portion 32a in the third direction.

[0038] The length L11 of the first end 31a in the third direction, the length L21 of the second end 32a in the third direction, the length of the first side surface conductive portion 51 in the third direction, and the length of the second side surface conductive portion 52 in the third direction are, for example, 0.4 mm. However, these lengths are not limited to this. These lengths may be set appropriately depending on, for example, the magnitude of the capacitive component required for the capacitive coupling between the first side surface conductive portion 51 and the first transmission line 31 and the capacitive coupling between the second side surface conductive portion 52 and the second transmission line 32.

[0039] The length L12 in the third direction of the first line portion 31b and the length L22 in the third direction of the second line portion 32b are set to lengths (line widths) that set the characteristic impedance to 50 Ω, for example. The length L12 in the third direction of the first line portion 31b and the length L22 in the third direction of the second line portion 32b are set to 0.2 mm, for example. However, these lengths are not limited to this. These lengths may be set appropriately depending on, for example, the required characteristic impedance.

[0040] The length in the second direction of the first end 31a and the length in the second direction of the second end 32a are, for example, 0.2 mm. The length in the first direction of the first side surface conductive portion 51 and the length in the first direction of the second side surface conductive portion 52 are, for example, 0.15 mm. However, these lengths are not limited to these. These lengths may be set appropriately depending on, for example, the required characteristic impedance.

[0041] The length in the second direction of the gap between the first substrate 21 and the second substrate 22 (the distance between the substrates) is, for example, 0.2 mm. The length in the first direction (thickness) of the first substrate 21 and the second substrate 22 is, for example, 0.2 mm. However, these lengths are not limited to this. The thickness and distance between the first substrate 21 and the second substrate 22 may be set arbitrarily so as to allow appropriate transmission of high-frequency signals. The length in the first direction of the second substrate 22 does not necessarily have to be the same as the length in the first direction of the second substrate 22. The length in the first direction of the second substrate 22 may be the same as or different from the length in the first direction of the second substrate 22.

[0042] One end of the bonding wire 14 is connected to, for example, the first end 31a of the first transmission line 31. The other end of the bonding wire 14 is connected to, for example, the second end 32a of the second transmission line 32. In this example, the two bonding wires 14 are arranged side by side in the third direction. The spacing between the two bonding wires 14 arranged side by side in the third direction is, for example, 0.12 mm. The bonding wires 14 are formed in an arc shape. In this case, the radius of the bonding wires 14 is, for example, 0.3 mm. The spacing and radius of each bonding wire 14 are not limited to those described above and may be set arbitrarily taking into consideration the manufacturability of the bonding wires 14 and the transmittance of high-frequency signals.

[0043] In this example, the first end 31a and the second end 32a are rectangular. The length L11 of the first end 31a in the third direction and the length L21 of the second end 32a in the third direction are substantially constant in the second direction. For example, the maximum value of the length L11 of the first end 31a in the third direction and the maximum value of the length L21 of the second end 32a in the third direction are 0.4 mm.

[0044] FIG. 4 is a circuit diagram that schematically illustrates an equivalent circuit of the high-frequency circuit according to the embodiment. As shown in FIG. 4, the high-frequency circuit 10 includes inductors Ld1, Ld2, and Lw, and capacitors Cd1, Cd2, Cc1, and Cc2.

[0045] The inductor Ld1 is an inductance component per unit length of the first transmission line 31. The inductor Ld2 is an inductance component per unit length of the second transmission line 32. The capacitor Cd1 is a capacitance component per unit length between the first transmission line 31 and the first back surface conductive part 41. The capacitor Cd2 is a capacitance component per unit length between the second transmission line 32 and the second back surface conductive part 42.

[0046] The inductor Lw is an inductance component of the bonding wire 14. In this example, the high-frequency circuit 10 has two bonding wires 14 aligned in the third direction. Therefore, the high-frequency circuit 10 has two inductors Lw corresponding to the two bonding wires 14, respectively. The two inductors Lw are provided between the inductor Ld1, which is an inductance component of the first transmission line 31, and the inductor Ld2, which is an inductance component of the second transmission line 32. The two inductors Lw are connected in parallel between the inductor Ld1 and the inductor Ld2.

[0047] Capacitor Cd1 and capacitor Cd2 are capacitances per unit length that are uniformly distributed on the substrate, and inductor Ld1 and inductor Ld2 are inductances per unit length that are uniformly distributed on the transmission line.

[0048] Capacitor Cc1 is a capacitance component between the first end 31a and the first side surface conductive portion 51. Capacitor Cc2 is a capacitance component between the second end 32a and the second side surface conductive portion 52. Capacitor Cc1 is provided, for example, between the inductor Lw and the capacitor Cd1 and in parallel with the capacitor Cd1. In other words, capacitor Cc1 is provided closer to the inductor Lw than the capacitor Cd1. Similarly, capacitor Cc2 is provided, for example, between the inductor Lw and the capacitor Cd2 and in parallel with the capacitor Cd2.

[0049] FIG. 5 is a graph schematically showing an example of a simulation result of the high-frequency circuit according to the embodiment. FIG. 6 is a graph schematically showing an example of a simulation result of a reference high-frequency circuit. 5 shows an example of a simulation result of the VSWR (Voltage Standing Wave Ratio) of the high-frequency circuit 10 using an electromagnetic field simulator (HFSS: High Frequency Structure Simulator). The horizontal axis in Fig. 5 and Fig. 6 represents the frequency of the high-frequency signal flowing through the first transmission line 31, the second transmission line 32, and the bonding wire 14. The vertical axis in Fig. 5 and Fig. 6 represents the VSWR versus frequency.

[0050] 6 shows an example of a simulation result of the VSWR of a reference high-frequency circuit. In the reference high-frequency circuit, the first substrate unit 11 and the second substrate unit 12 do not have the first side surface conductive portion 51 and the second side surface conductive portion 52, and the first transmission line 31 and the second transmission line 32 do not have the first end portion 31a and the second end portion 32a. In other words, the reference high-frequency circuit does not have capacitors Cc1 and Cc2 in the equivalent circuit.

[0051] When the first substrate unit 11 and the second substrate unit 12 are electrically connected via the bonding wire 14, the bonding wire 14 has an inductance component as shown in Fig. 4. Therefore, the bonding wire 14 becomes one of the factors that hinder the widening of the bandwidth of the high-frequency circuit 10. For example, the bonding wire 14 becomes one of the factors that deteriorate the VSWR.

[0052] For example, in a reference high-frequency circuit that does not have first side surface conductive portion 51, second side surface conductive portion 52, first end portion 31a, or second end portion 32a, the VSWR exceeds 1.2 at frequencies above 11 GHz due to the influence of unnecessary inductance of bonding wire 14, as shown in Fig. 6. In this way, in the reference high-frequency circuit, the VSWR deteriorates at frequencies above X band, for example.

[0053] In contrast, in the high-frequency circuit 10 according to this embodiment, the first substrate unit 11 and the second substrate unit 12 have the first side surface conductive portion 51 and the second side surface conductive portion 52, and the first transmission line 31 and the second transmission line 32 have the first end portion 31a and the second end portion 32a. As a result, the capacitance component (capacitor Cc1) generated between the first end portion 31a and the first side surface conductive portion 51 and the capacitance component (capacitor Cc2) generated between the second end portion 32a and the second side surface conductive portion 52 cancels out the 50 Ω matching error caused by the inductance component (inductor Lw) of the bonding wire 14, thereby suppressing deterioration of the VSWR.

[0054] 5, for example, a VSWR of 1.2 or less is obtained even at 37 GHz, which is a favorable characteristic. The high-frequency circuit 10 according to this embodiment can ensure impedance matching over a wide band, including the inductance component of the bonding wire 14.

[0055] The magnitude of the capacitance component generated between the first transmission line 31 (first end 31a) and the first side conductive portion 51, and the magnitude of the capacitance component generated between the second transmission line 32 (second end 32a) and the second side conductive portion 52 may be adjusted appropriately according to the magnitude of the inductance component of the bonding wire 14.

[0056] The magnitude of the capacitance component generated between the first end 31a and the first side surface conductive portion 51 can be adjusted as desired by adjusting, for example, the length L11 of the first end 31a in the third direction, the length of the first side surface conductive portion 51 in the third direction, and the distance between the first end 31a and the first side surface conductive portion 51. The magnitude of the capacitance component generated between the second end 32a and the second side surface conductive portion 52 can be adjusted in the same way as the magnitude of the capacitance component generated between the first transmission line 31 and the first side surface conductive portion 51.

[0057] In this way, the high-frequency circuit 10 according to this embodiment can achieve high transmission efficiency over a wide band. In the high-frequency circuit 10 according to this embodiment, even when the first substrate portion 11 and the second substrate portion 12 are connected via bonding wires 14, the transmission efficiency between the first substrate portion 11 and the second substrate portion 12 can be improved.

[0058] 7(a) to 7(c) are cross-sectional views that schematically show an example of a method for manufacturing a high-frequency circuit according to an embodiment. 7(a), the method for manufacturing the high-frequency circuit 10 includes the steps of forming a first substrate portion 11 and a second substrate portion 12. The steps of forming the first substrate portion 11 and the second substrate portion 12 include the steps of forming a first transmission line 31, a first back surface conductive portion 41, and a first side surface conductive portion 51 on the first substrate 21, and forming a second transmission line 32, a second back surface conductive portion 42, and a second side surface conductive portion 52 on the second substrate 22.

[0059] The first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51 are formed on the first substrate 21 by, for example, film formation by sputtering or the like and patterning by photolithography, etching, or the like. The film formation is not limited to sputtering, and other film formation methods such as vapor deposition and plating may also be used.

[0060] The first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51 may be formed by a method in which a conductive film is deposited and then patterned to form the respective shapes of the first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51, or by a method in which a resist or the like is patterned into the respective shapes of the first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51, and then film deposition to form the first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51.

[0061] The step of forming the first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51 on the first substrate 21 includes, for example, a step of forming the first transmission line 31 on the first substrate 21, a step of forming the first back surface conductive portion 41 on the first substrate 21, and a step of forming the first side surface conductive portion 51 on the first substrate 21. The first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51 are, for example, formed individually on the first substrate 21. The first transmission line 31, the first back surface conductive portion 41, and the first side surface conductive portion 51 may be formed in any order that makes it easy to form them.

[0062] 7(c), the method for manufacturing the high-frequency circuit 10 includes a step of connecting the first transmission line 31 and the second transmission line 32 via the bonding wire 14. In this way, the high-frequency circuit 10 is manufactured.

[0063] FIG. 8 is a plan view schematically illustrating a modified example of the high-frequency circuit according to the embodiment. It should be noted that components that are substantially the same in function and configuration as those in the above embodiment are given the same reference numerals and detailed explanations thereof will be omitted. 8, in the high-frequency circuit 10a, the first transmission line 31 does not have a first end 31a, and the second transmission line 32 does not have a second end 32a. In the high-frequency circuit 10a, the line widths of the first transmission line 31 and the second transmission line 32 are substantially constant.

[0064] In the high-frequency circuit 10a, the length in the third direction of the first side surface conductive portion 51 is set to be, for example, approximately the same as the length in the third direction of one end in the second direction of the first transmission line 31. The length in the third direction of the second side surface conductive portion 52 is set to be, for example, approximately the same as the length in the third direction of one end in the direction opposite to the second direction of the second transmission line 32.

[0065] 8, the first transmission line 31 and the second transmission line 32 do not necessarily have the first end 31a and the second end 32a. As shown in Fig. 8, the first side surface conductive portion 51 is capacitively coupled to the first transmission line 31 having a substantially constant line width, and the second side surface conductive portion 52 is capacitively coupled to the second transmission line 32 having a substantially constant line width. In this case as well, the capacitive component generated between the first transmission line 31 and the first side surface conductive portion 51 and the capacitive component generated between the second transmission line 32 and the second side surface conductive portion 52 can suppress the influence of the inductance component of the bonding wire 14 and suppress deterioration of the VSWR.

[0066] As described in the above embodiment, when the first end 31a is provided on the first transmission line 31 and the second end 32a is provided on the second transmission line 32, it is possible to further increase, for example, the capacitance component generated between the first transmission line 31 and the first side surface conductive portion 51 and the capacitance component generated between the second transmission line 32 and the second side surface conductive portion 52. Therefore, for example, when the inductance component of the bonding wire 14 is large, providing the first end 31a and the second end 32a makes it easy to cancel out the deviation in 50 Ω matching caused by the inductance component of the bonding wire 14.

[0067] FIG. 9 is a plan view schematically illustrating a modified example of the high-frequency circuit according to the embodiment. As shown in FIG. 9, in the high-frequency circuit 10b, the second substrate unit 12 is replaced with a semiconductor element 34. The semiconductor element 34 is provided on the conductor 16. The semiconductor element 34 is, for example, directly soldered to the conductor 16. The semiconductor element 34 has, for example, a substrate unit 35 (second substrate), a terminal unit 36 ​​(surface conductive portion), and a terminal unit 37. The terminal units 36 and 37 are provided side by side on the substrate unit 35 so as to face the first direction.

[0068] The semiconductor element 34 includes, for example, a HEMT (High Electron Mobility Transistor) or a MESFET (Metal-Semiconductor Field Effect Transistor). The high-frequency circuit 10b functions, for example, as a high-frequency amplifier that amplifies an input high-frequency signal using the semiconductor element 34 and outputs the amplified high-frequency signal. The terminal unit 37 is, for example, an input terminal unit for inputting a high-frequency signal, and the terminal unit 36 ​​is, for example, an output terminal unit for outputting the amplified high-frequency signal.

[0069] In the high-frequency circuit 10b, the bonding wire 14 connects the first transmission line 31 and the terminal portion 36. As a result, for example, a high-frequency signal output from the semiconductor element 34 is transmitted via the bonding wire 14 and the first transmission line 31. Note that, for example, opposite to the above, the terminal portion 36 may be an input terminal portion, the terminal portion 37 may be an output terminal portion, and the high-frequency signal transmitted from the first transmission line 31 may be input to the semiconductor element 34 via the bonding wire 14 and the terminal portion 36.

[0070] Also in the high-frequency circuit 10b, the first substrate portion 11 has a first side surface conductive portion 51 that is provided on the first side surface 21b and is capacitively coupled to the first transmission line 31. As a result, also in the high-frequency circuit 10b, the effect of the inductance component of the bonding wire 14 can be suppressed by the capacitive component generated between the first transmission line 31 and the first side surface conductive portion 51, and deterioration of the VSWR can be suppressed.

[0071] In this way, the first side conductive portion 51 may be provided not only when connecting transmission lines (the first transmission line 31 and the second transmission line 32) via a bonding wire 14, but also when connecting the first transmission line 31 and a semiconductor element 34 via a bonding wire 14.

[0072] Furthermore, the surface conductive portion provided on the second substrate portion is not limited to the second transmission line 32 or the terminal portion 36 of the semiconductor element 34, and may be any conductive portion. When the transmission line provided on the first substrate portion and the surface conductive portion provided on the second substrate portion are connected via a bonding wire, a first side surface conductive portion is provided on the first substrate portion and capacitively coupled to the transmission line. This makes it possible to suppress the influence of the inductance component of the bonding wire and to suppress deterioration of VSWR, even when connecting two substrates via a bonding wire. High transmission efficiency can be obtained in high-frequency circuits.

[0073] Furthermore, in the high-frequency circuit 10b, the semiconductor element 34 (second substrate portion) does not have the second side surface conductive portion 52. In this way, the second substrate portion does not necessarily have to have the second side surface conductive portion 52. In the high-frequency circuit, it is sufficient that the first substrate portion 11 has at least the first side surface conductive portion 51 that is capacitively coupled to the first transmission line 31. When the second substrate portion is provided with the second side surface conductive portion 52, the capacitance component generated between the surface conductive portion and the second side surface conductive portion 52 can make it easier to adjust the suppression of the inductance component of the bonding wire 14, for example.

[0074] The present embodiment includes the following aspects. (Appendix 1) a first substrate having a first surface facing a first direction and a first side surface facing a second direction perpendicular to the first direction; a transmission line provided on the first surface; a first substrate portion having a second substrate arranged next to the first substrate at a predetermined interval in the second direction and having a second surface facing the first direction; a surface conductive portion provided on the second surface; a second substrate portion having a bonding wire connecting the transmission line and the surface conductive portion; Equipped with The first substrate portion is a high-frequency circuit provided on the first side surface and having a first side surface conductive portion that is capacitively coupled to the transmission line.

[0075] (Appendix 2) the second substrate has a second side surface facing in a direction opposite to the second direction; 2. The high-frequency circuit according to claim 1, wherein the second substrate portion has a second side surface conductive portion provided on the second side surface and capacitively coupled to the surface conductive portion.

[0076] (Appendix 3) the transmission line has an end portion provided at one end in the second direction and a line portion extending from the end portion in a direction opposite to the second direction, 3. The high-frequency circuit according to claim 1, wherein the length of the end portion in a third direction perpendicular to each of the first direction and the second direction is longer than the length of the line portion in the third direction.

[0077] (Appendix 4) 4. The high-frequency circuit according to claim 1, wherein the first substrate portion sets the potential of the first side surface conductive portion to a ground potential.

[0078] (Appendix 5) a conductor set to the ground potential; the first substrate portion and the second substrate portion are arranged side by side on the conductor, The high-frequency circuit of claim 4, wherein the first substrate portion further has a back surface conductive portion electrically connected to the conductor, and the potential of the first side surface conductive portion is set to the ground potential by electrically connecting the first side surface conductive portion to the back surface conductive portion.

[0079] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0080] DESCRIPTION OF SYMBOLS 10, 10a, 10b...high frequency circuit, 11...first substrate portion, 12...second substrate portion, 14...bonding wire, 16...conductor, 21...first substrate, 22...second substrate, 31...first transmission line, 31a...first end portion, 31b...first line portion, 32...second transmission line, 32a...second end portion, 32b...second line portion, 34...semiconductor element, 35...substrate portion, 36, 37...terminal portion, 41...first back surface conductive portion, 42...second back surface conductive portion, 51...first side surface conductive portion, 52...second side surface conductive portion, Cc1, Cc2, Cd1, Cd2...capacitor, Ld1, Ld2, Lw...inductor

Claims

1. a first substrate having a first surface facing a first direction and a first side surface facing a second direction perpendicular to the first direction; a transmission line provided on the first surface; a first substrate portion having a second substrate arranged next to the first substrate at a predetermined interval in the second direction and having a second surface facing the first direction; a surface conductive portion provided on the second surface; a second substrate portion having a bonding wire connecting the transmission line and the surface conductive portion; Equipped with The first substrate portion is a high-frequency circuit having a first side surface conductive portion provided on the first side surface and capacitively coupled to the transmission line.

2. the second substrate has a second side surface facing in a direction opposite to the second direction; 2. The high-frequency circuit according to claim 1, wherein the second substrate portion has a second side surface conductive portion provided on the second side surface and capacitively coupled to the surface conductive portion.

3. the transmission line has an end portion provided at one end in the second direction and a line portion extending from the end portion in a direction opposite to the second direction, The high-frequency circuit according to claim 1 , wherein the length of the end portion in a third direction perpendicular to each of the first direction and the second direction is longer than the length of the line portion in the third direction.

4. The high-frequency circuit according to claim 1 , wherein the first substrate portion sets the potential of the first side surface conductive portion to a ground potential.

5. a conductor set to the ground potential; the first substrate portion and the second substrate portion are provided side by side on the conductor, 5. The high-frequency circuit according to claim 4, wherein the first substrate portion further has a back surface conductive portion electrically connected to the conductor, and the potential of the first side surface conductive portion is set to the ground potential by electrically connecting the first side surface conductive portion to the back surface conductive portion.

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