High-frequency module

Abstract

To provide a high-frequency module capable of improving high-frequency transmission characteristics.SOLUTION: A high-frequency module includes: a metal package 40 to which a connector 50 and a connector 60 are attached; a first transmission path substrate 10 in which a grounded coplanar transmission path 14 is formed on a substrate body comprising quartz, a central conductor of the connector 50 being electrically connected to an end of the signal line pattern, an external conductor of the connector being electrically connected to a rear face ground pattern; a second transmission path substrate 20 in which a grounded coplanar transmission path 24 is formed on a substrate body comprising quartz, a central conductor of the connector 60 being electrically connected to an end of a signal line pattern, an external conductor of the connector being electrically connected to a rear face ground pattern; and an integral circuit element 30 including an integrated circuit 31 having an input side connected to the transmission path 14 and an output side connected to the transmission path 24. The line length of the transmission path 14 is different from the line length of the transmission path 24.SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] For example, there is a demand for a high-frequency module configured by modularizing a traveling-wave amplifier capable of amplifying a high-frequency PAM4 (Pulse Amplitude Modulation 4) signal exceeding 100 Gbaud. Generally, such a high-frequency module is housed, for example, in a metal package with an input transmission line, an integrated circuit, and an output transmission line connected in sequence, and a high-frequency signal input to an input connector attached to the package is amplified by the integrated circuit through the input transmission line, and the amplified signal is taken out from an output connector attached to the package through the output transmission line. In high-frequency modules for amplifying high-frequency signals and the like, various measures have been taken to suppress deterioration of transmission characteristics due to impedance mismatch and the like (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a transmission device that changes characteristic impedance by changing the pattern width of a signal line and the substrate thickness to prevent deterioration of transmission characteristics due to impedance mismatch.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional technology as described in Patent Document 1, since the characteristic impedance was changed by varying the pattern width of the signal line and the substrate thickness, the adjustment of the characteristic impedance was complicated. Also, it was difficult to remove the dips (hereinafter also referred to as dips) seen in the transmission characteristics such as the reflection characteristics and transmission characteristics of the high-frequency module.

[0006] The present invention has been made to solve such problems, and an object thereof is to provide a high-frequency module capable of improving the high-frequency transmission characteristics of the entire module.

Means for Solving the Problems

[0007] The high-frequency module of the present invention includes a metal package (40) to which a first connector (50) and a second connector (60) are attached, and a first transmission substrate (10) housed in the package. On the surface of a first transmission substrate body (11) made of a dielectric, a first transmission line (14) is formed, which consists of a first signal line pattern (12) and first ground patterns (13, 13) arranged at intervals on both sides of the first signal line pattern. A first back surface ground pattern (15) is formed on the back surface of the first transmission substrate body. The center conductor (51) of the first connector is electrically connected to the end of the first signal line pattern, and the outer conductor (52) of the first connector is electrically connected to the first back surface ground pattern. A second transmission substrate (20) is also housed in the package. On the surface of a second transmission substrate body (21) made of a dielectric, a second transmission line (24) is formed, which consists of a second signal line pattern (22) and second ground patterns (23, 23) arranged at intervals on both sides of the second signal line pattern. A second back surface ground pattern (25) is formed on the back surface of the second transmission substrate body. The center conductor (61) of the second connector is electrically connected to the end of the second signal line pattern, and the outer conductor (62) of the second connector is electrically connected to the second back surface ground pattern. An integrated circuit element (30) having an integrated circuit (31) with an input side connected to the first transmission line and an output side connected to the second transmission line is provided. The line length of the first transmission line and the line length of the second transmission line are set so that they are different from each other.

[0008] With this configuration, the high-frequency module of the present invention can suppress the phenomenon in which the dips generated depending on the line lengths of the first transmission line and the second transmission line are emphasized by setting the line lengths of the first transmission line and the second transmission line to be different from each other. In this way, by suppressing the emphasis of the dips in the transmission characteristics, the high-frequency transmission characteristics of the entire module can be improved.

[0009] Also, in the high-frequency module of the present invention, the line length of the first transmission line and the line length of the second transmission line may be set such that the frequency at which the gain of the integrated circuit alone peaks is equal to the frequency at which a dip occurs, which is a drop in the transmission characteristics of the entire high-frequency module.

[0010] With this configuration, the high-frequency module of the present invention sets the line lengths of the first transmission line and the second transmission line so that the frequency at which the gain of the integrated circuit alone peaks is equal to the frequency at which a dip occurs in the transmission characteristics of the entire high-frequency module, thereby canceling out the dip in the transmission characteristics of the entire high-frequency module. In this way, the high-frequency transmission characteristics of the entire high-frequency module can be improved.

Effects of the Invention

[0017] According to the present invention, it is possible to provide a high-frequency module capable of improving the high-frequency transmission characteristics of the entire module.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 10

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Figure 14

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0020] FIG. 1 is a diagram showing the configuration of a high-frequency module according to an embodiment of the present invention. The high-frequency module 1 is a high-frequency module capable of amplifying a high-frequency PAM4 signal exceeding, for example, 100 Gbaud. As shown in FIG. 1, the high-frequency module 1 includes a first transmission line substrate 10 provided with an input-side transmission line 14, a second transmission line substrate 20 provided with an output-side transmission line 24, an integrated circuit element 30 having an integrated circuit 31 such as an amplifier circuit, and a metal package 40 housing these components. Connectors 50 for input and 60 for output are attached to the package 40.

[0021] (First Transmission Line Substrate) As shown in FIGS. 2 and 7, on the surface 11a of a substrate body 11 made of a dielectric such as quartz, for example, a linear signal line pattern 12 made of a metal foil and ground (GND) patterns 13, 13 arranged at intervals on both sides of the signal line pattern 12 are formed on the input-side first transmission line substrate 10. Hereinafter, the combination of the signal line pattern 12 and the GND patterns 13, 13 is referred to as a transmission line 14. A GND pattern 15 (also referred to as a back surface GND pattern) is formed on the back surface 11b or an intermediate layer. That is, a grounded coplanar line type transmission line 14 is formed on the first transmission line substrate 10.

[0022] On the first transmission circuit board 10, a plurality of via holes 16 penetrating from the front surface 11a to the back surface 11b of the board body 11 are formed, electrically connecting the GND pattern 13 on the front surface 11a and the back surface GND pattern 15. The more via holes 16, the better for achieving electrical connection between the GND pattern 13 and the back surface GND pattern 15. However, if there are too many, the strength of the first transmission circuit board 10 will be weakened. Therefore, the number and arrangement can be appropriately set to ensure sufficient electrical connection while maintaining the required strength. In the middle of the signal line pattern 12 of this embodiment, a silicon capacitor 19 for cutting DC components is provided, but it may be omitted if necessary.

[0023] (Second transmission circuit board) As shown in FIG. 7, the output-side second transmission circuit board 20 has the same configuration as the input-side first transmission circuit board 10. The output-side second transmission circuit board 20 has, for example, a linear signal line pattern 22 made of metal foil and GND patterns 23, 23 arranged at intervals on both sides of the signal line pattern 22 formed on the front surface 21a of a board body 21 made of a dielectric such as quartz. The combination of the signal line pattern 22 and the GND patterns 23, 23 is also referred to as a transmission line 24. A GND pattern 25 (also referred to as a back surface GND pattern) is formed on the back surface 21b. That is, a grounded coplanar line type transmission line 24 is formed on the second transmission circuit board 20.

[0024] On the second transmission circuit board 20, a plurality of via holes 26 penetrating from the front surface 21a to the back surface 21b of the board body 21 are formed, electrically connecting the GND pattern 23 on the front surface 21a and the back surface GND pattern 25. A silicon capacitor 29 is provided in the middle of the signal line pattern 22 to improve the transmission characteristics.

[0025] (Integrated circuit element) As shown in Fig. 7, it has an integrated circuit 31 with its input side connected to the transmission line 14 of the first transmission line substrate 10 and its output side connected to the transmission line 24 of the second transmission line substrate 20. Specifically, in the integrated circuit element 30, an integrated circuit (IC) 31 such as an amplifier circuit is formed on a semiconductor substrate (or chip), and it includes an input terminal 32a, an input-side GND terminal 32b, an output terminal 33a, and an output-side GND terminal 33b. The input terminal 32a is connected to the input side of the integrated circuit 31 within the integrated circuit element 30 and is connected to one end of the signal line pattern 12 of the first transmission line substrate 10 by, for example, one or more wires. The input-side GND terminal 32b is connected to the GND of the integrated circuit 31 within the integrated circuit element 30 and is connected to the GND pattern 13 of the first transmission line substrate 10 by, for example, one or more wires. The output terminal 33a is connected to the output side of the integrated circuit 31 within the integrated circuit element 30 and is connected to one end of the signal line pattern 22 of the second transmission line substrate 20 by, for example, one or more wires. The output-side GND terminal 33b is connected to the GND of the integrated circuit 31 within the integrated circuit element 30 and is connected to the GND pattern 23 of the second transmission line substrate 20 by, for example, one or more wires.

[0026] (Package) The package 40 is made of metal. Specifically, it has a metal container 41 and a metal lid. The lid is attached to the container 41 to form an internal space surrounded by metal walls, and the first transmission line substrate 10, the integrated circuit element 30, and the second transmission line substrate 20 are accommodated in the internal space. Through holes are formed in the opposing wall portions 43a, 43b of the container 41, and coaxial connectors 50 and 60 such as W connectors are respectively attached to the through holes. The input connector 50 includes a center conductor 51 and an outer conductor 52 formed coaxially with respect to the center conductor 51 via an insulating material. The output connector 60 includes a center conductor 61 and an outer conductor 62 formed coaxially with respect to the center conductor 61 via an insulating material. Also, a radio wave absorber is attached to the back side of the metal lid so as to suppress spatial resonance in the formed internal space.

[0027] (Connection Structure) Next, the connection structure 100 between the metal package 40 and the transmission line 14 of the first transmission substrate 10 will be described.

[0028] As shown in FIG. 2, the center conductor 51 of the connector 50 is electrically connected to the end of the signal line pattern 12 of the first transmission substrate 10 by soldering or the like. The outer conductor 52 of the connector 50 is electrically connected to the wall portion 43 of the package 40 and is also electrically connected to the back surface GND pattern 15 of the first transmission substrate 10 via the wall portion 43, an appropriate conductive member, or directly.

[0029] <Arrangement of via holes in the GND pattern> In the first transmission substrate 10, via holes 16 for connecting the GND pattern 13 and the back surface GND pattern 15 are formed in a row along the edge on the side of the GND pattern 13 facing the signal line pattern 12. The via holes 16 are arranged such that the distance between the edge of the GND pattern 13 (i.e., the boundary or end defining the GND pattern 13) and the via holes 16 is equal to the lower limit value of the design rule which is a manufacturing limitation. Here, the distance between the edge of the GND pattern 13 and the via holes 16 refers to the shortest distance from the edge (boundary) of the GND pattern 13 on the side facing the signal line pattern 12 to the end of the via holes 16 on the signal line pattern 12 side. Also, the via holes 16 are arranged such that the interval between adjacent via holes 16, 16 is equal to the lower limit value of the design rule. Here, the interval between adjacent via holes 16, 16 refers to the interval between the ends of the via holes 16 closer to each other. Specifically, in this embodiment, for example, the distance between the edge of the GND pattern 13 and the via holes 16 is 0.05 mm, and the interval between adjacent via holes 16, 16 is 0.2 mm.

[0030] Also, the more via holes 16 there are in the GND pattern 13, the more electrically integrated the back GND pattern 15 connected to the metal package 40 and the GND pattern 13 on the surface 11a becomes. However, the risk of the first transmission base board 10 cracking increases. Therefore, it is preferable to minimize the number of via holes 16. For this reason, the via holes 16 may be arranged along the edge of the GND pattern 13. In the present embodiment, in addition to the row of via holes 16 arranged along the edge on the side of the GND pattern 13 facing the signal line pattern 12, along the edge on the side of the GND pattern 13 opposite to the side facing the signal line pattern 12, a row of via holes 16 for connecting the GND pattern 13 and the back GND pattern 15 is formed. In the present embodiment, the via holes 16 are limited to only these two rows in one GND pattern 13. Also, in order to reduce the risk of the first transmission base board 10 cracking, the diameter of the via holes 16 is set to the lower limit value of the design rules.

[0031] <Cancellation> According to the design rules, the via holes 16 cannot be arranged at the board edge of the first transmission base board 10. Therefore, in the first transmission base board 10, the area between the via holes 16 from the board edge on the side of the wall portion 43a of the package 40 is a region where the metal package 40 and the GND pattern 13 on the surface 11a of the first transmission base board 10 are not directly connected. Therefore, by providing a cancellation 17 for metallizing the side surface 11c of the first transmission base board 10 in this region, the metal package 40 and the GND pattern 13 are sufficiently electrically connected up to the board edge of the first transmission base board 10.

[0032] Specifically, on the edge of the substrate body 11 of the first transmission circuit board 10 on the side facing the wall portion 43a of the package 40 on the side where the connector 50 is attached, a castellation 17 is formed by metallizing the side surface 11c of the substrate body 11 to conduct the GND pattern 13 and the back surface GND pattern 15. The shape of the castellation 17 in plan view may be any shape such as a semi-circle, semi-ellipse, rectangle, etc., and the number can also be arbitrarily set. In this embodiment, on one side of the first transmission circuit board 10 that is rectangular in plan view and facing the wall portion 43a of the package 40, two castellations 17 having a rectangular shape with rounded corners in plan view are provided, and two castellations 17 having a similar shape are also provided on the side opposite to this side.

[0033] Also, in the GND pattern 13 of the first transmission circuit board 10, between the via holes 16 from the substrate end where the via holes 16 cannot be arranged, the metal package 40 and the GND pattern 13 on the surface 11a are not directly connected. Therefore, a connection conductor 18 made of a metal (for example, gold) for connecting the external conductor 52 of the connector 50 or the package 40 connected to the external conductor 52 and the GND pattern 13 on the surface 11a is provided.

[0034] <Simulation results> FIG. 3(a) shows a simulation model of the first transmission circuit board 10A used in the connection structure 100 according to this embodiment, and (b) shows the simulation results of the reflection characteristics, and (c) shows the simulation results of the transmission characteristics. In FIGS. 3(b) and (c), the broken line indicates the case (configuration example 1) where the distance d1 between the edge of the GND pattern 13 and the via hole 16 is set to 168 μm, and the solid line indicates the case (configuration example 2) where the distance d1 between the edge of the GND pattern 13 and the via hole 16 is set to 50 μm, which is the lower limit value of the design rule. As shown in FIGS. 3(b) and (c), in configuration example 1, it was confirmed that a dip in the reflection characteristics occurs near 120 GHz, and when the distance d1 between the edge of the GND pattern 13 and the via hole 16 is reduced in configuration example 2, the transmission performance is improved.

[0035] FIG. 4(a) shows a simulation model of the first transmission substrate 10B used in the connection structure 100 according to the present embodiment, (b) shows the simulation results of the reflection characteristics, and (c) shows the simulation results of the transmission characteristics. In FIGS. 4(b) and (c), the solid line indicates the case where the castellations 17 are formed (Configuration Example 3), and the dashed line indicates the case where the castellations are not formed (the above Configuration Example 1) for comparison. As shown in FIGS. 4(b) and (c), in Configuration Example 3, it was confirmed that the band with good transmission characteristics extends by forming the castellations 17.

[0036] FIG. 5(a) shows a simulation model of the first transmission substrate 10C used in the connection structure 100 according to the present embodiment, (b) shows the simulation results of the reflection characteristics, and (c) shows the simulation results of the transmission characteristics. In this case (Configuration Example 4), the distance d1 between the edge of the GND pattern 13 and the via hole 16 is set to 50 μm, which is the lower limit value of the design rule, and eight castellations 17 are formed. Further, in order to prevent the substrate from cracking, the via holes 16 are arranged along the edge of the GND pattern 13, and the number of via holes 16 is reduced compared to Configuration Example 3 of FIG. 4. As shown in FIGS. 5(b) and (c), in Configuration Example 4, even if the number of via holes 16 is suppressed to this extent, by setting the distance d1 between the edge of the GND pattern 13 and the via hole 16 to 50 μm, which is the lower limit value of the design rule, and forming the castellations 17, it was confirmed that the transmission characteristics can be improved.

[0037] Fig. 6(a) shows a simulation model of the first transmission circuit board 10 used in the connection structure 100 according to this embodiment, (b) shows the simulation results of the reflection characteristics, and (c) shows the simulation results of the transmission characteristics. In this case (example), via holes 16 are formed only along the edges on the side of the GND pattern 13 facing the signal line pattern 12 and the edges on the opposite side, reducing the number of via holes 16 compared to Configuration Example 4 of Fig. 5 and minimizing the number. In this example, the distance d1 between the edge of the GND pattern 13 and the via hole 16 is set to 50 μm, which is the lower limit of the design rule, and four castellations 17 are formed. As shown in Figs. 6(b) and (c), even when the number of via holes 16 is minimized in this example, by setting the distance d1 between the edge of the GND pattern 13 and the via hole 16 to 50 μm, which is the lower limit of the design rule, and forming the castellations 17, it was confirmed that the transmission characteristics can be improved.

[0038] Although the connection structure between the first transmission circuit board 10 and the package 40 has been described, the same applies to the connection structure between the second transmission circuit board 20 and the package 40.

[0039] (Improvement of Transmission Characteristics of High-Frequency Module) Next, the improvement of the transmission characteristics of the high-frequency module 1 will be described.

[0040] As shown in Fig. 7, the high-frequency module 1 includes a metal package 40 to which a coaxial connector 50 on the input side and a coaxial connector 60 on the output side are attached, a first transmission circuit board 10, a second transmission circuit board 20, and an integrated circuit element 30. The first transmission circuit board 10 has a transmission path 14 formed by a signal line pattern 12 and a pair of GND patterns 13, 13 arranged at intervals on both sides of the signal line pattern 12 on the surface 11a of a substrate body 11 made of a dielectric such as quartz. A back surface GND pattern 15 is formed on the back surface 11b of the substrate body 11. The center conductor 51 of the connector 50 is electrically connected to the end of the signal line pattern 12, and the outer conductor 52 of the connector 50 is electrically connected to the back surface ground pattern 15.

[0041] The second transmission line board 20 has a transmission path 24 formed by a signal line pattern 22 on the surface 21a of a board body 21 made of a dielectric such as quartz, and a pair of GND patterns 23, 23 arranged at intervals on both sides of the signal line pattern 22. A back surface GND pattern 25 is formed on the back surface 21b of the board body 21. The center conductor 61 of the connector 60 is electrically connected to the end of the signal line pattern 22, and the outer conductor 62 of the connector 60 is electrically connected to the back surface ground pattern 25. An integrated circuit element 30 has an integrated circuit 31 formed thereon, and the integrated circuit 31 has an input terminal 32a connected to the other end of the signal line pattern 12 and an output terminal 33a connected to the other end of the second signal line pattern 22.

[0042] If there is impedance mismatch at the connection part between the connector 50 and the transmission path 14 and at the connection part between the transmission path 14 and the integrated circuit 31, multiple reflections of signals occur in the transmission path 14, and dips in the transmission characteristics appear. The frequency at which such dips occur due to multiple reflections is determined depending on the length of the transmission path 14. The same applies to the transmission path 24. The frequency at which dips in the transmission characteristics occur due to multiple reflections etc. caused by impedance mismatch is determined depending on the length of the transmission path 24. Therefore, it has been found that if the lengths of the input-side transmission path 14 and the output-side transmission path 24 are made the same, the dips in the transmission characteristics depending on the lengths of the transmission paths 14 and 24 will be emphasized.

[0043] Therefore, in the high-frequency module 1 according to the present embodiment, in order to avoid emphasizing the dips in the transmission characteristics, the line length of the input-side transmission path 14 and the line length of the output-side transmission path 24 are set such that the line length of the transmission path 14 and the line length of the transmission path 24 are different from each other. Alternatively, the board length in the transmission path longitudinal direction of the first transmission line board 10 and the board length in the transmission path longitudinal direction of the second transmission line board 20 are made different from each other.

[0044] Even in the entire high-frequency module 1, depending on the dielectric constant of the substrate bodies 11 and 21 of the dielectric and the substrate of the integrated circuit element 30, and the lengths of the transmission lines 14 and 24 and the integrated circuit 31 (wavelength in the dielectric), a drop (dip) in the transmission characteristics of the entire module occurs (see part B in FIG. 9(c)). Specifically, the frequency at which a dip in the transmission characteristics occurs due to multiple reflections caused by impedance mismatch, etc. is determined depending on, for example, the total length of the transmission line 14, the integrated circuit 31, and the transmission line 24.

[0045] On the other hand, the integrated circuit 31 has a gain peak when alone. FIG. 8 shows the result of actually measuring the transmission characteristics of the integrated circuit element 30 alone. As can be seen from FIG. 8, there is a gain peak around 80 GHz (see part A in FIG. 8).

[0046] Therefore, in the high-frequency module 1 according to the present embodiment, the line length of the input-side transmission line 14 and the line length of the output-side transmission line 24 are set so that the frequency at which the gain of the integrated circuit 31 alone peaks is equal to the frequency at which a dip, which is a drop in the transmission characteristics of the entire high-frequency module 1, occurs, thereby canceling out the dip in the transmission characteristics.

[0047] Also, in the first transmission substrate 10, the via holes 16 formed on the GND pattern 13 are arranged so that the distance between adjacent via holes 16, 16 and the distance between the substrate edge of the substrate body 11 and the via hole 16 become smaller, so that the metal package 40 and the GND pattern 13 on the surface 11a of the first transmission substrate 10 are electrically integrated and the transmission characteristics are improved. However, the minimum values of the distance between adjacent via holes 16, 16 and the distance between the substrate edge and the via hole 16 are limited by design rules. Also, when the number of via holes 16 increases, the strength of the substrate body 11 made of dielectric decreases. Considering these, the number, interval, etc. of the via holes 16 are appropriately set so as to maintain the required substrate strength while ensuring the required transmission characteristics. Although the first transmission substrate 10 has been described, the same applies to the second transmission substrate 20.

[0048] Specifically, in this embodiment, the various quantities are as follows, which are illustrative and not limited to these numerical values. The integrated circuit element 30 has a length of 2.08 mm in the signal propagation direction (x-axis direction), and the measured value of the peak gain of the integrated circuit 31 alone was 80 GHz. The materials of the substrate bodies 11 and 21 are quartz. It is presumed that in order to generate a dip at 80 GHz for the entire high-frequency module 1, the total length of the high-frequency module 1 may be adjusted to 7.9 mm. When subtracting the length of the integrated circuit element 30, the total length of the input-side transmission line 14 and the output-side transmission line 24 may be set to 5.8 mm. Considering the design rules, the distance between adjacent via holes 16, 16 and the distance between the substrate end and the via hole 16 in the first transmission line substrate 10, and the distance between adjacent via holes 26, 26 and the distance between the substrate end and the via hole 26 in the second transmission line substrate 20 are set to the lower limit values of the design rules, respectively. The lengths of the selectable transmission lines 14 and 24 are limited. Among them, the length of the input-side transmission line 14 in the signal propagation direction (x-axis direction) is preferably 3.3 mm, and the length of the output-side transmission line 24 is preferably 2.4 mm.

[0049] <Simulation results> First, FIG. 9(a) shows the simulation model of the high-frequency module 1A, (b) shows the simulation results of the reflection characteristics, and (c) shows the simulation results of the transmission characteristics. In the high-frequency module 1A in this case (Reference Example 1), the line length L1 of the input-side transmission line 14 and the line length L1 of the output-side transmission line 24 are set to be equal. As shown in FIGS. 9(b) and (c), it was confirmed that the transmission characteristics deteriorate at 80 GHz or higher, and there is a dip (shown as part B) near 75 GHz in the entire high-frequency module 1A. Also, in the transmission lines 14 and 24 alone, there is a dip near 120 GHz (see the broken-line graph (Configuration Example 1) in FIG. 3(c)).

[0050] Fig. 10(a) shows a high-frequency module 1B provided with connection conductors 18 and 28, and Figs. (b) and (c) are diagrams showing the measured results of reflection characteristics and transmission characteristics respectively (Reference Example 2). In this Reference Example 2, a connection conductor 18 is provided for connecting the external conductor 52 of the connector 50 and the GND pattern 13 on the surface 11a of the first transmission substrate 10. Similarly, for the second transmission substrate 20, a connection conductor 28 is provided for connecting the external conductor 62 of the connector 60 and the GND pattern 23 on the surface 21a of the second transmission substrate 20. The graphs shown in gray in Figs. 10(b) and (c) represent the case where no connection conductor is used. As shown in Figs. 10(b) and (c), it was confirmed that in Reference Example 2, the transmission characteristics at 80 GHz and above were improved compared to the case where no connection conductor was used (the graph shown in gray).

[0051] Fig. 11 relates to a signal transmission simulation performed by changing the substrate length L1 of the first transmission substrate 10. Fig. (a) shows the simulation model, and Figs. (b) and (c) are diagrams showing the simulation results of reflection characteristics and transmission characteristics respectively. The dips within 110 GHz were as follows in the table below.

[0052] [Table 1]

[0053] From these simulation results, it was confirmed that the frequency at which dips in transmission characteristics occur due to multiple reflections etc. caused by impedance mismatch is determined depending on the substrate length L1 (i.e., the transmission line length). Also, within 80 GHz, it was found that the shorter the substrate length L1, the better the transmission characteristics. Further, at 80 GHz and above, it was confirmed that starting from around 80 GHz, the transmission characteristics began to deteriorate in the case where the substrate length was the shortest (1.76 mm), and a dip appeared around 100 GHz.

[0054] FIG. 12(a) shows a simulation model (Reference Example 3) in which the line lengths of the input-side transmission line 14 and the output-side transmission line 24 are set to be different from each other in Reference Example 1 of FIG. 9, (b) shows the reflection characteristics, and (c) is a diagram showing the simulation results of the transmission characteristics. In the high-frequency module 1C of Reference Example 3, the line length L1 of the input-side transmission line 14 is set to 3.30 mm, and the line length L2 of the output-side transmission line 24 is set to 2.40 mm so that the two are different from each other. As shown in FIGS. 12(b) and (c), it was confirmed that the dip in the entire high-frequency module was suppressed as compared with Reference Example 1 (FIG. 9).

[0055] FIG. 13 shows the results of simulating the transmission characteristics with the high-frequency module 1 according to the present embodiment shown in FIG. 7 as a simulation model. FIG. 13(a) shows the simulation results of the reflection characteristics, and (b) shows the simulation results of the transmission characteristics (Example). In the high-frequency module 1 of this example, the line length L1 of the input-side transmission line 14 is 3.30 mm, and the line length L2 of the output-side transmission line 24 is 2.59 mm, and the two are different. As shown in FIGS. 13(a) and (b), it was confirmed that the -3 dB band is 107 GHz and the transmission characteristics at 80 GHz or higher are improved as compared with Reference Example 1 (FIG. 9).

[0056] FIG. 14(a) shows the eye diagram of the input signal to the high-frequency module in the simulation, (b) shows the eye diagram of the output signal from the high-frequency module 1 according to the embodiment of the present invention, and (c) shows the eye diagram of the output signal from the high-frequency module 1A according to Reference Example 1 (FIG. 9). In the high-frequency module 1 according to the present embodiment, it was confirmed that the eye opening is improved as compared with Reference Example 1.

[0057] (Operation and Effect) In the high-frequency module 1 according to this embodiment, the line length of the transmission line 14 on the input side and the line length of the transmission line 24 on the output side are set such that the line length of the transmission line 14 and the line length of the transmission line 24 are different from each other. With this configuration, the high-frequency module 1 of this embodiment can suppress the phenomenon in which the dip generated depending on the line lengths of the transmission line 14 and the transmission line 24 is emphasized. In this way, by suppressing the emphasis of the dip in the transmission characteristics, the high-frequency transmission characteristics of the entire high-frequency module 1 can be improved.

[0058] Further, the line length of the transmission line 14 on the input side and the line length of the transmission line 24 on the output side are set such that the frequency at which the gain of the integrated circuit 31 alone peaks is equal to the frequency at which the dip in the transmission characteristics of the entire high-frequency module 1 occurs. With this configuration, the dip in the transmission characteristics of the entire high-frequency module 1 can be offset, and the high-frequency transmission characteristics of the entire high-frequency module can be improved.

[0059] Note that the signal line pattern 12, GND pattern 13, transmission line 14, back surface GND pattern 15, via hole 16, catenation 17, and connection conductor 18 of this embodiment respectively correspond to the first signal line pattern, first GND pattern, first transmission line, first back surface GND pattern, first via hole, first catenation, and first connection conductor of the present invention. Also, the signal line pattern 22, GND pattern 23, transmission line 24, back surface GND pattern 25, via hole 26, catenation 27, and connection conductor 28 of this embodiment respectively correspond to the second signal line pattern, second GND pattern, second transmission line, second back surface GND pattern, second via hole, second catenation, and second connection conductor of the present invention.

Industrial Applicability

[0060] As described above, the present invention has the effect of improving the high-frequency transmission characteristics of the entire module and is useful for high-frequency modules in general.

Explanation of Reference Numerals

[0061] 1, 1A, 1B, 1C High-frequency Modules 10, 10A, 10B, 10C First Transmission Circuit Boards 11 Substrate Body (First Substrate Body) 11a, 21a Surfaces 11b, 21b Back Surfaces 11c, 21c Side Surfaces 12 Signal Line Pattern (First Signal Line Pattern) 13 GND Pattern (First GND Pattern) 14 Transmission Line (First Transmission Line) 15 Back Surface GND Pattern (First Back Surface GND Pattern) 16 Via Hole (First Via Hole) 17 Cancellation (First Cancellation) 18 Connection Conductor (First Connection Conductor) 19, 29 Silicon Capacitors 20 Second Transmission Circuit Board 21 Substrate Body (Second Substrate Body) 22 Signal Line Pattern (Second Signal Line Pattern) 23 GND Pattern (Second GND Pattern) 24 Transmission Line (Second Transmission Line) 25 Back Surface GND Pattern (Second Back Surface GND Pattern) 26 Via Hole (Second Via Hole) 27 Cancellation (Second Cancellation) 28 Connection Conductor (Second Connection Conductor) 30 Integrated Circuit Element 31 Integrated Circuit 32a Input Terminal 32b Input-side GND Terminal 33a Output Terminal 33b Output-side GND Terminal 40 Package 41 Container 43, 43a, 43b Wall Parts 50 Connector (First Connector) 51 Central Conductor 52 Outer Conductor 60 Connector (Second Connector) 61 Central Conductor 62 Outer conductor 100 Connection structure

Claims

1. A metal package (40) to which a first connector (50) and a second connector (60) are attached, A first transmission line substrate (10) housed in the package, on the surface of a first transmission line substrate body (11) made of a dielectric, a first signal line pattern (12) and first ground patterns (13, 13) arranged at intervals on both sides of the first signal line pattern are formed to form a first transmission line (14), a first back surface ground pattern (15) is formed on the back surface of the first transmission line substrate body, the center conductor (51) of the first connector is electrically connected to the end of the first signal line pattern, and the outer conductor (52) of the first connector is electrically connected to the first back surface ground pattern, A second transmission line substrate (20) housed in the package, on the surface of a second transmission line substrate body (21) made of a dielectric, a second signal line pattern (22) and second ground patterns (23, 23) arranged at intervals on both sides of the second signal line pattern are formed to form a second transmission line (24), a second back surface ground pattern (25) is formed on the back surface of the second transmission line substrate body, the center conductor (61) of the second connector is electrically connected to the end of the second signal line pattern, and the outer conductor (62) of the second connector is electrically connected to the second back surface ground pattern, An integrated circuit element (30) having an integrated circuit (31) with an input side connected to the first transmission line and an output side connected to the second transmission line, A high-frequency module, characterized in that the line length of the first transmission line and the line length of the second transmission line are set so that the line length of the first transmission line and the line length of the second transmission line are different from each other.

2. The high-frequency module according to claim 1, wherein the line length of the first transmission line and the line length of the second transmission line are set so that the frequency at which the gain of the integrated circuit alone peaks is equal to the frequency at which a dip, which is a drop in the transmission characteristics of the entire high-frequency module, occurs.

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