JP2021150906A - Coupling circuit - Google Patents

Abstract

To provide a simply structured compact coupling circuit which couples a DC current to be used for a light-receiving and emitting device with a high frequency AC current in an optical signal transmission circuit which handles a high frequency signal of a GHz class or higher.SOLUTION: The coupling circuit includes: a parallel running part, having a first conductor and a second conductor running in parallel at a preset interval, and including a meandering part in which the parallel-running first and second conductors meander; a third conductor which forms the ground of an electric signal transmitted by the first conductor; and a fourth conductor which forms the ground of an electric signal transmitted by the second conductor, so that the electric signal is transmitted between the first conductor and the second conductor in the parallel running part. The first electric signal transmitted by the first conductor penetrates into the second conductor in the same direction as the transmission direction of the first conductor. A second electric signal having a different frequency from the first electric signal is applied to the second electric conductor.SELECTED DRAWING: Figure 8A

Description

The present invention relates to a coupling circuit that combines a direct current used in a light emitting element or a light receiving element and a high frequency alternating current in an optical signal transmission circuit that handles high frequency signals of the gigahertz class or higher. In particular, a simple configuration in which each of the direct current and high-frequency alternating current that need to be applied to the light emitting element is further added with a conductor such as a circuit board pattern and, if necessary, an element formed of a resistor or a conductor. Concerning techniques for providing coupling circuits in.

In order to convert a high-frequency electric signal of Gigahertz class or higher into a good optical signal, a DC current as an appropriate bias current is applied to a light emitting element such as a laser to emit light at a constant output, and then high-frequency AC is emitted. It is necessary to superimpose electric currents to generate an optical signal that produces the intensity of light.

For this purpose, a coupling circuit of a DC component and an AC component, which is generally called a bias tea (Bias-Tee), is used. Bias tees are generally composed of many inductors and capacitors, which tend to be costly and bulky.

For example, in Patent Document 1, as for the inductor required for the high-pass filter in the bias tee, only the high-frequency coil and the mid-frequency coil are used to reduce the low-frequency coil. Instead, with respect to the low frequency band, by newly configuring a low-pass filter circuit, a bias corresponding to the low frequency band component is applied to the driven element.

JP-A-2007-241142

According to the above-mentioned Patent Document 1, the inductor used for the high-pass filter can be reduced, but the inductors for the high region and the mid region remain, and for the low region, a new detection circuit including an operational amplifier or the like is required. There was a problem that the circuit became large and the cost increased.

The present invention has been made in view of the problems of the prior art. An object of the present invention is that an inductor or a capacitor is not required, and a tortuous portion having a small bending radius provided on a circuit board is provided, so that a small conductor such as a transmission path pattern and a terminating resistor are sufficient for a good direct current. To combine high frequency alternating current with.

In the coupling circuit according to the aspect of the present invention, the first conductor and the second conductor run in parallel at predetermined intervals, and the first conductor and the second conductor running in parallel run in parallel. A parallel running portion having a meandering portion, a third conductor forming a ground for an electric signal transmitted by the first conductor, and a ground for an electric signal transmitted by the second conductor. A bond that includes a fourth conductor that is connected to the third conductor and that an electric signal is transmitted between the first conductor and the second conductor in the parallel running portion. In the circuit, in the parallel running portion, the first electric signal transmitted by the first conductor is transmitted to the second conductor in the same direction as the transmission direction of the first conductor, and the second conductor is transmitted. It is preferable that a second electric signal having a frequency different from that of the first electric signal is applied to the second conductor.

With respect to the bending radius of the meandering portion in the parallel running portion, the first electric signal input from one end portion of the first conductor is reflected from the terminal portion of the first conductor to the one end portion. It is preferable that the bending radius is in a range in which the amount of reflection in the case does not exceed a predetermined value.

The distance between the first conductor and the second conductor of the parallel running portion is set so that the length of the parallel running portion is shorter than the predetermined coupling peak frequency. The coupling peak frequency is preferably the frequency at which the attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest.

The first conductor and the third conductor are located at the end of the first conductor located on the side opposite to one end of the first conductor to which the first electric signal is applied. It is preferable that a terminating resistor having a value within ± 20% of the value of the characteristic impedance formed by the body is connected between the terminating portion and the third conductor.

The first conductor and the third conductor are located at the end of the first conductor located on the side opposite to one end of the first conductor to which the first electric signal is applied. It is preferable that an inductor having a value within ± 20% of the value of the characteristic impedance formed by the body is connected between the terminal portion and the third conductor.

The shorter the parallel portion of the first conductor and the second conductor, the higher the coupling peak frequency of the first electric signal, and the coupling peak frequency of the first conductor and the first conductor. It is preferable that the frequency at which the amplitude attenuation of the first electric signal transmitted between the two conductors is the smallest is the smallest.

The narrower the distance between the first conductor and the second conductor in the parallel running portion of the first conductor and the second conductor, the closer the coupling peak frequency of the first electric signal becomes. It is preferable that the coupling peak frequency becomes low and the attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest.

The coupling circuit according to the aspect of the present invention further includes a circuit board, and the first conductor and the second conductor are wirings formed on the surface of the circuit board, and the third conductor is the third conductor. The fourth conductor is preferably a ground formed on the back surface of the circuit board.

An inductor in which the second conductor is spirally formed is formed at an input portion of the second conductor into which the second electric signal is input, and the impedance of the inductor at the frequency of the first electric signal is It is preferable that the characteristic impedance formed by the second conductor and the fourth conductor is within ± 20%.

One end of the first conductor is port 1, the end of the first conductor is port 2, one end of the second conductor is port 3, and the end of the second conductor. When the unit is port 4, the first electric signal input to the port 1 is output from the port 4, the second electric signal is output from the port to the port 4, and the port 1 and the port 1 are described. It is preferable that the port 3 and the port 4 are respectively equipped with an external device and a connector for transmitting and receiving the first electric signal and the second electric signal.

According to the present invention, the number of mounting components such as inductors, capacitors, and operational amplifiers can be reduced, so that not only the component cost and mounting cost can be reduced, but also the bending radius of the parallel running portion of the circuit pattern can be reduced to about 1 mm. It is possible to significantly reduce the size. Further, according to the present invention, it is possible to cope with a device having a low power supply impedance only by forming an inductor according to a circuit pattern.

It is a figure which shows the basic concept of the coupling circuit realized by the circuit board which concerns on this embodiment. It is a figure which shows an example of the frequency characteristic of a transmitted signal and a reflected signal in the coupling circuit of FIG. 1A. It is a figure which shows a part of the parameter of the coupling circuit which concerns on this embodiment. It is a figure which shows the change of the coupling peak frequency when the coupling transmission line spacing of the parameter of FIG. 2A is changed. It is a figure which shows the change of the coupling peak frequency when the coupling transmission line spacing of the parameter of FIG. 2A is 0.7mm. It is a figure which shows the change of the coupling peak frequency when the coupling transmission line spacing of the parameter of FIG. 2A is 1.0mm. It is a figure which shows the change of the coupling peak frequency when the coupling transmission line spacing of the parameter of FIG. 2A is 2.0mm. It is a figure which shows the change of the coupling peak frequency when the coupling transmission line length of the parameter of FIG. 2A is changed. FIG. 2 is a diagram showing an example of a coupling circuit in which a coaxial connector is mounted on the coupling circuit of FIG. 2A and a terminating resistor is mounted on the port 2. It is a figure which shows an example of the frequency characteristic of the transmission signal and the reflection signal of the coupling circuit of FIG. 3A. FIG. 3 is a diagram showing an example of a configuration in which a low output impedance power supply device is input to port 3 in the coupling circuit of FIG. 3A. It is a figure which shows an example of the frequency characteristic of the transmission signal and the reflection signal of the coupling circuit of FIG. 4A. It is a figure which shows an example of the structure which formed the inductor in the input part of the port 3 in the coupling circuit of FIG. 4A. It is a figure which shows an example of the frequency characteristic of the transmission signal and the reflection signal of the coupling circuit of FIG. 5A. FIG. 5A is a diagram showing an example of a configuration in which the terminating resistor of the port 2 is removed and the port 2 is opened in the coupling circuit of FIG. 5A. It is a figure which shows an example of the frequency characteristic of the transmission signal and the reflection signal of the coupling circuit of FIG. 6A. It is a top view of the coupling circuit of FIG. 5A. It is a figure which shows an example of the mounting area of the port 4 connector of the coupling circuit of FIG. 5A, and the terminating resistor of port 2. It is a figure which shows an example of the mounting area of the port 1 connector of the coupling circuit of FIG. 5A. It is a figure which shows an example of the region in which the inductor formed in the upper part of the mounting region of the port 3 connector of the coupling circuit of FIG. 5A is formed. It is a figure which shows an example of the mounting area of the port 3 connector of the coupling circuit of FIG. 5A. It is a figure which shows another example of the coupling circuit which concerns on this embodiment. It is a figure which shows an example of the frequency characteristic of the transmission signal and the reflection signal of the coupling circuit of FIG. 8A. It is a figure which supplements the coupling circuit of FIG. 8A. It is another configuration example of the port 2 of the coupling circuit of FIG. 8A. It is a figure which shows an example of the coupling circuit which shows the other example of the port 2 which concerns on this embodiment. It is a figure which shows an example of the coupling circuit part which provides a plurality of parallel running parts which concerns on this embodiment.

(Outline of the characteristics of the coupling circuit formed on the circuit board)
As the configuration of the coupling circuit 1000 of the present embodiment, two copper foil patterns (copper foil pattern 1 (100) and copper foil pattern 2 (200)) provided in parallel on the circuit board 300 shown in FIG. 1A are configured. ), The ground 500 provided as a plane on the back surface of the circuit board 300 is included. Further, the basic configuration is a terminating resistor (not shown) or an inductor mounted on port 2 (320) of the coupling circuit 1000. However, a configuration in which a terminating resistor is not mounted on the port 2 (320) may be used as the basic configuration. Further, in the following description of the present embodiment, an example of a coupling circuit for driving a light emitting element (not shown) connected to the port 4 (340) will be described in detail. Port 2 (320) and port 4 (340) will be described below.

The port 1 (310) is an input unit for a high-frequency AC signal in the copper foil pattern 1 (100). Basically, a transmission line such as a coaxial cable having a characteristic impedance of 50Ω is connected. The high frequency AC signal supplied to the copper foil pattern 1 (100) is transmitted by the transmission line.

Port 2 (320) is the end of copper foil pattern 1 (100). A terminating resistor of 50Ω may or may not be mounted between the terminating portion and the ground 500 provided on the back surface of the circuit board 300. In FIG. 1A, in order to explain the basic operation, the case where the terminating resistor is mounted is shown numerically.

The port 3 (330) is an input unit for a DC signal such as a bias current supplied to the light emitting element in the copper foil pattern 2 (200). A power supply device or the like (not shown) having a low output impedance, which will be described later, is basically connected to the port 3 (330). In FIG. 1A, in order to explain the basic operation, a case where a device (not shown) having an output impedance of 50Ω is connected is illustrated.

The port 4 (340) is a copper foil in which a high-frequency AC signal transmitted from the copper foil pattern 1 (100) to the copper foil pattern 2 (200) is superimposed on the DC signal input from the port 3 (330) and output. This is the output unit in pattern 2 (200). Port 4 (340) is a port to which a driven device such as a light emitting element is connected.

The parallel running portion 350 is a section in which the copper foil pattern 1 (100) and the copper foil pattern 2 (200) run in parallel at a predetermined distance. In the parallel running portion 350, the high-frequency AC signal input from the port 1 (310) to the copper foil pattern 1 (100) is transmitted to the copper foil pattern 2 (200). The high-frequency AC signal is gradually transmitted in the direction from port 3 (330) to port 4 (340), which is the same direction as the direction from port 1 (310) to port 2 (320). This transmission utilizes a phenomenon in which an AC signal component is coupled from the copper foil pattern 1 (100) to the copper foil pattern 2 (200).

The frequencies that are most efficiently coupled are the length of the parallel running portion 350, the distance between the copper foil pattern 1 (100) and the copper foil pattern 2 (200) in the parallel running portion 350, and the transmission lines inside and outside the circuit board 300. It changes depending on the parameters such as the characteristic impedance of. Hereinafter, the length of the parallel running portion 350 may be referred to as a coupled transmission line length, and the distance between the copper foil pattern 1 (100) and the copper foil pattern 2 (200) in the parallel running portion 350 may be referred to as a coupled transmission line spacing.

FIG. 1B shows a transmitted signal transmitted from port 1 (310) to port 4 (340) and reflected from port 1 (310) to port 1 (310) when a high-frequency AC signal is input to port 1 (310). The frequency characteristics of the reflected signal are shown. In the example of FIG. 1B, the coupling is most efficient at around 7.2 GHz, and the attenuation of the amplitude of the transmitted signal is the smallest. Hereinafter, the frequency at which the amplitude attenuation of the high-frequency AC signal transmitted between the copper foil pattern 1 (100) and the copper foil pattern 2 (200) is the smallest is referred to as a coupling peak frequency.

As described above, the coupling peak frequency can be arbitrarily selected by changing the parameters including the coupling transmission line spacing and the coupling transmission line length. According to these configurations and operations, it can be seen that the bias tee function can be realized only by the circuit pattern and the terminating resistor without separately providing an inductor or a capacitor.

(Specific specifications of the coupling circuit)
FIG. 2A is a diagram showing a part of the parameters of the coupling circuit. L is the combined transmission line length, and corresponds to the lengths of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) in FIG. 2A. Gap is a coupled transmission line spacing, and corresponds to the spacing between the copper foil pattern 1 (100) and the copper foil pattern 2 (200) in FIG. 2A. W is the width of the transmission line, and corresponds to the width of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) in FIG. 2A. In FIG. 2A, the widths of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) are the same. t is the thickness of the circuit board. Table 1 shows specific values of the parameters of the coupling circuit of FIG. 2A.

FIG. 2B is a diagram showing a change in the coupling peak frequency when the coupling transmission line spacing is changed in the coupling circuit of FIG. 2A having the parameter values of Table 1. The horizontal axis of FIG. 2B indicates the coupling transmission line spacing [mm], and the vertical axis of FIG. 2B indicates the coupling peak frequency [GHz]. In FIG. 2B, when the coupling transmission line spacing is changed from 2 mm to 0.2 mm, the coupling peak frequency changes from about 12 GHz to about 6 GHz. That is, the coupling peak frequency decreases as the coupling transmission line spacing becomes narrower.

FIG. 2C shows a transmitted signal transmitted from port 1 (310) to port 4 (340) when a high-frequency AC signal is input to port 1 (310) when the combined transmission line spacing of FIG. 2B is 0.7 mm. Shows the frequency characteristics of. FIG. 2C also shows the frequency characteristics of the reflected signal reflected from port 1 (310) to port 1 (310). The horizontal axis of FIG. 2C indicates the frequency [GHz], and the vertical axis indicates the amplitude [dB] of the transmitted signal and the reflected signal. Since the reflected signal is reduced to about -20 dB or less, it is shown that the influence on the transmitted signal is small. In the example of FIG. 2C, the coupling peak frequency exists in the vicinity of 7.0 GHz, indicating that the coupling peak frequency is the maximum value.

FIG. 2D shows a transmitted signal transmitted from port 1 (310) to port 4 (340) when a high-frequency AC signal is input to port 1 (310) when the combined transmission line spacing of FIG. 2B is 1.0 mm. Shows the frequency characteristics of. Further, FIG. 2D shows the frequency characteristics of the reflected signal reflected from the port 1 (310) to the port 1 (310). The horizontal axis of FIG. 2D indicates the frequency [GHz], and the vertical axis indicates the amplitude [dB] of the transmitted signal and the reflected signal. Since the reflected signal is reduced to about -20 dB or less, it is shown that the influence on the transmitted signal is small. In the example of FIG. 2D, the coupling peak frequency exists in the vicinity of 7.8 GHz, indicating that the coupling peak frequency is the maximum value.

FIG. 2E shows a transmitted signal transmitted from port 1 (310) to port 4 (340) when a high-frequency AC signal is input to port 1 (310) when the combined transmission line spacing of FIG. 2B is 2.0 mm. Shows the frequency characteristics of. Further, FIG. 2E shows the frequency characteristics of the reflected signal reflected from the port 1 (310) to the port 1 (310). The horizontal axis of FIG. 2E indicates the frequency [GHz], and the vertical axis indicates the amplitude [dB] of the transmitted signal and the reflected signal. Since the reflected signal is reduced to about -20 dB or less, it is shown that the influence on the transmitted signal is small. In the example of FIG. 2E, the coupling peak frequency exists in the vicinity of 12.0 GHz, indicating that the coupled peak frequency is the maximum value.

FIG. 2F is a diagram showing a change in the coupling peak frequency when the coupling transmission path length is changed in the coupling circuit of FIG. 2A having the parameter values of Table 1. The horizontal axis of FIG. 2F indicates the coupled transmission line length [mm], and the vertical axis of FIG. 2F indicates the coupled peak frequency [GHz]. In FIG. 2F, when the coupled transmission line length is changed from about 175 mm to about 25 mm, the coupled peak frequency changes from about 5 GHz to about 43 GHz. That is, the shorter the combined transmission line length, the higher the combined peak frequency.

According to the above configuration example, a coupling circuit of 10 GHz or more can be simply configured by using a circuit pattern configuration of a general Gala Epo system within about 10 cm.

(Specific example of a coupling circuit with a coaxial connector mounted)
In FIGS. 3A, 4A, 5A and 6A, a coaxial connector mounting area is added to the end of the circuit board according to the actual usage pattern, and the area is directed toward the 28 GHz band, which is expected to be used in the 5th generation wireless communication. An example of the configuration is shown. Table 2 shows the parameter values of the circuit board 300 and the coupling circuit 1000 of FIGS. 3A, 4A, 5A and 6A.

(Example 1)
FIG. 3A shows a form in which a coaxial connector is mounted on a coupling circuit having the parameter values in Table 1. The characteristic impedance of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of FIG. 3A is about 50Ω. Further, a coaxial connector 311 is mounted on the port 1 (310) in order to input a high frequency AC signal. The characteristic impedance of the coaxial connector 311 is about 50Ω. A coaxial cable having a characteristic impedance of about 50Ω for transmitting a high-frequency AC signal is connected to the coaxial connector 311. The mounting area of the port 1 is referred to as an area A101 (360), and the details of the area A101 (360) are shown in FIG. 7C. As shown in FIG. 7C, the coaxial connector 311 is mounted across the port 1 connector mounting area 1 (361) and the port 1 connector mounting area 2 (362). The copper foil pattern 1 (100) extends between the port 1 connector mounting area 1 (361) and the port 1 connector mounting area 2 (362) to the end of the circuit board 300.

Further, a terminating resistor 321 having an impedance of 50Ω is mounted on the port 2 (320) for the purpose of suppressing reflection of a high-frequency AC signal. The terminating resistor 321 is mounted so as to connect between the copper foil pattern 1 (100) and the ground on the back surface of the circuit board 300. Details of the area where the terminating resistor 321 is mounted are shown in FIG. 7B. The terminating resistor 321 is mounted in the terminating resistor mounting area 383 of FIG. 7B. Port 2 (320), which is the end of the copper foil pattern 1 (100) adjacent to the right side of the terminating resistor mounting area 383 of FIG. 7B, is connected to the terminating resistor 321. Further, the left end portion of the terminating resistor mounting region 383 of FIG. 7B is connected to the back surface of the circuit board 300 via a through hole or the like. The impedance of the terminating resistor 321 has a value within ± 20% of the value of the characteristic impedance of the copper foil pattern 1 (100).

The port 3 (330) functions as a DC input unit for inputting a DC signal to the copper foil pattern 2 (200). A power supply device having a low output impedance is generally connected to the DC signal, but in FIG. 3A, the output impedance of the device connected to the port 3 is set to about 50Ω. Therefore, since it matches the characteristic impedance of the copper foil pattern 2 (200), the influence on the high frequency AC signal transmitted through the copper foil pattern 2 (200) is reduced. That is, in the case of this embodiment, the flatness of the transmitted signal transmitted through the copper foil pattern 2 (200) with respect to the frequency change is maintained.

A coaxial connector 341 for outputting a transmission signal of a high-frequency AC signal and a superimposed signal in which a DC signal input to the port 3 (330) is superimposed is mounted on the port 4 (340). The characteristic impedance of the coaxial connector 341 is about 50Ω. A coaxial cable having a characteristic impedance of about 50Ω for transmitting a superimposed signal is connected to the coaxial connector 341. A light emitting element such as a laser diode is connected to the other end of the coaxial cable. The DC signal is used to define the bias level of the light emitting element, and the transmitted signal can also be used as a carrier signal or an information signal for information transport. The mounting area of port 4 (340) is included in a part of area A103 (380), and the details of area A101 (360) are shown in FIG. 7C as described above. As shown in FIG. 7C, the coaxial connector 341 is mounted across the port 4 connector mounting area 1 (381) and the port 4 connector mounting area 2 (382). The copper foil pattern 2 (200) extends between the port 4 connector mounting area 1 (381) and the port 4 connector mounting area 2 (382) to the end of the circuit board 300.

The characteristic impedance of the copper foil pattern 1 (100) of FIGS. 3A, 4A, 5A and 6A, the characteristic impedance of the copper foil pattern 2 (200), and the coaxial cable connected to the copper foil pattern 1 (100). The variation between the characteristic impedances is within ± 20%.

Further, between the characteristic impedance of the copper foil pattern 1 (100) of FIGS. 1A and 2A, the characteristic impedance of the copper foil pattern 2 (200), and the characteristic impedance of the transmission line connected to the copper foil pattern 1 (100). The variation is within ± 20%.

FIG. 3B shows a transmission signal when a high-frequency AC signal is input to port 1 (310) of the coupling circuit of FIG. 3A, a DC signal is input to port 3 (330), and a superimposed signal is output from port 4 (340). It is a figure which showed the frequency characteristic of a reflected signal. The transmitted signal is a transmitted component of the high-frequency AC signal measured at port 4 (340), and the reflected signal is a reflected component of the high-frequency AC signal measured at port 1 (310). The horizontal axis of FIG. 3B is the frequency [GHz], and the vertical axis is the amplitude [dB] of the transmitted signal and the reflected signal. The combined peak frequency of the transmitted signal is around 28.0 GHz, and the transmitted signal is obtained most efficiently at the target 28.0 GHz. Further, although the transmitted signal is attenuated by about 1 dB, the amount of attenuation is less than about 1 dB by optimizing the structure and suppressing variations in the manufacturing of the structure.

According to the above configuration example, even when a general coaxial connector is mounted on a glass epoxy circuit board, it is expected to be used in 5th generation wireless communication by using a circuit pattern configuration within about 5 cm. The coupling circuit near 28.0 GHz can be simply configured.

(Example 2)
FIG. 4A also shows a form in which a coaxial connector is mounted on a coupling circuit having the parameter values in Table 1. The characteristic impedance of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of FIG. 4A is about 50Ω. Further, port 1 (310), port 2 (320) and port 4 (340) have the same configuration as that in FIG. 3A. A coaxial connector 311 is connected to the port 1 (310), a terminating resistor 321 is connected to the port 2 (320), and a coaxial connector 341 is mounted on the port 4 (340). To avoid duplication of description, refer to the description of FIG. 3A for port 1 (310), port 2 (320) and port 4 (340).

Port 3 (330), which is different from the configuration of FIG. 3A, will be described below. Port 3 (330) functions as a DC input unit for inputting a DC signal. A power supply device having a low output impedance is generally connected to a DC signal. Therefore, the configuration shown in FIG. 4A is a configuration in which the output impedance of the device connected to the port 3 (330) is lowered to 1Ω. In this case, impedance mismatch is given to the AC component, so that the flatness of the frequency characteristic deteriorates. FIG. 4B shows how the flatness of the frequency characteristics has deteriorated.

FIG. 4B shows a transmission signal when a high-frequency AC signal is input to port 1 (310) of the coupling circuit of FIG. 4A, a DC signal is input to port 3 (330), and a superimposed signal is output from port 4 (340). It is a figure which showed the frequency characteristic of a reflected signal. The transmitted signal is a transmitted component of the high-frequency AC signal measured at port 4 (340), and the reflected signal is a reflected component of the high-frequency AC signal measured at port 1 (310). The horizontal axis of FIG. 4B is the frequency [GHz], and the vertical axis is the amplitude [dB] of the transmitted signal and the reflected signal. The combined peak frequency of the transmitted signal is around 28.0 GHz, and the transmitted signal is obtained most efficiently at the target 28.0 GHz. Also, the transmitted signal is attenuated by about 1 dB, which can be optimized to less than about 1 dB. Compared with the transmitted signal of FIG. 3B, the flatness of the frequency characteristics is deteriorated in the transmitted signal of about 20 GHz or less and the transmitted signal of about 40 GHz or more, but the flatness of the frequency characteristics is deteriorated in the vicinity of the target 28.0 GHz. It is maintained.

According to the above configuration example, even if a DC signal is generally supplied by a power supply device having a low output impedance, it is expected to be used in 5th generation wireless communication by using a configuration of a circuit pattern within about 5 cm28. A coupling circuit near 0.0 GHz can be easily configured.

(Example 3)
FIG. 5A also shows a form in which a coaxial connector is mounted on a coupling circuit having the parameters shown in Table 1. The characteristic impedance of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of FIG. 5A is about 50Ω. Further, port 1 (310), port 2 (320) and port 4 (340) have the same configuration as that in FIG. 3A. A coaxial connector 311 is connected to the port 1 (310), a terminating resistor 321 is connected to the port 2 (320), and a coaxial connector 341 is mounted on the port 4 (340). To avoid duplication of description, refer to the description of FIG. 3A for port 1 (310), port 2 (320) and port 4 (340).

Port 3 (330), which differs from the configurations of FIGS. 3A and 4A, will be described below. Port 3 (330) functions as a DC input unit for inputting a DC signal. A power supply device having a low output impedance is generally connected to a DC signal. Therefore, the configuration of FIG. 5A is a configuration in which the output impedance of the device connected to the port 3 (330) is 1Ω, which is as low as in FIG. 4A. In this case, as described with reference to FIG. 4A, impedance mismatch is given to the AC component, so that the flatness of the frequency characteristic deteriorates. However, in FIG. 5A, in order to improve the deterioration of the flatness of the frequency characteristic, the inductor 400 is formed in the DC input portion of the port 3 (330) to improve the flatness of the frequency characteristic.

The region in which the inductor 400 is formed in the DC input portion of the port 3 (330) is referred to as an area C101 (390), and the details of the area C101 (390) are shown in FIG. 7D. As shown in FIG. 7D, the impedance in the high frequency band is increased by forming the inductor 400 by the spiral circuit pattern. As a result, in the copper foil pattern 2 (200), only the impedance mismatch of the high frequency component is improved without affecting the DC component, and the flatness of the frequency response characteristic is improved.

The radius of the inductor 400 shown in FIG. 7D is about 5 mm, and the distance from the start of winding to the end of winding of the circuit pattern is about 4 mm. The impedance near the target 28.0 GHz is about 50 Ω, and it is possible to form a value of about 0.37 nH of self-inductance. Further, no ground is formed on the back surface of the circuit board 300 corresponding to the region where the inductor 400 of the area C101 (390) is formed. Further, the impedance of the inductor 400 at the frequency of the high-frequency AC signal transmitting the copper foil pattern 1 (100) is within ± 20% of the characteristic impedance of the copper foil pattern 2 (200).

FIG. 5B shows a transmission signal when a high-frequency AC signal is input to port 1 (310) of the coupling circuit of FIG. 5A, a DC signal is input to port 3 (330), and a superimposed signal is output from port 4 (340). It is a figure which showed the frequency characteristic of a reflected signal. The transmitted signal is a transmitted component of the high-frequency AC signal measured at port 4 (340), and the reflected signal is a reflected component of the high-frequency AC signal measured at port 1 (310). The horizontal axis of FIG. 5B is the frequency [GHz], and the vertical axis is the amplitude [dB] of the transmitted signal and the reflected signal. The combined peak frequency of the transmitted signal is around 28.0 GHz, and the transmitted signal is obtained most efficiently at the target 28.0 GHz. Further, the transmitted signal is attenuated by about 2 dB, which can be reduced to less than 1 dB by the above-mentioned optimization. Compared with the transmitted signal of FIG. 4B, the flatness of the frequency characteristics is improved in the transmitted signal of about 20 GHz or less and the transmitted signal of about 40 GHz or more, and the flatness of the frequency characteristics in the vicinity of the target 28.0 GHz is also improved. It has been improved.

According to the above configuration example, even if a DC signal is generally supplied by a power supply device having a low output impedance, it is around 28.0 GHz by using a circuit pattern configuration within about 5 cm including an inductor 400 formed by the circuit pattern. The coupling circuit in can be easily configured. That is, stable coupling characteristics can be realized without the need for additional mounting components such as inductors and capacitors, even in consideration of the shape for actual use, the impedance of the connection destination, and the like. As described above, a substantially flat frequency characteristic can be obtained with an insertion loss of about 1 dB in a range of at least ± 1 GHz with respect to the target frequency of 28 GHz.

(Example 4)
FIG. 6A also shows a form in which a coaxial connector is mounted on a coupling circuit having the parameters shown in Table 1. The characteristic impedance of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of FIG. 6A is about 50Ω. Further, port 1 (310), port 3 (330) and port 4 (340) have the same configuration as that in FIG. 5A. A coaxial connector 311 is connected to the port 1 (310), and a coaxial connector 341 is mounted on the port 4 (340). A coaxial connector 331 is connected to the port 3 (330) to form an inductor 400. The terminating resistor 321 is not connected to the port 2 (320). Therefore, the port 2 (320) is in the open state. That is, the coupling circuit of FIG. 6A is different from the coupling circuit of FIG. 5A in that the port 2 (320) is in an open state. In order to avoid duplication of description, refer to the description of FIGS. 3A and 5A for port 1 (310), port 3 (330), and port 4 (340).

FIG. 6B shows a transmission signal when a high-frequency AC signal is input to port 1 (310) of the coupling circuit of FIG. 6A, a DC signal is input to port 3 (330), and a superimposed signal is output from port 4 (340). It is a figure which showed the frequency characteristic of a reflected signal. The transmitted signal is a transmitted component of the high-frequency AC signal measured at port 4 (340), and the reflected signal is a reflected component of the high-frequency AC signal measured at port 1 (310). The horizontal axis of FIG. 5B is the frequency [GHz], and the vertical axis is the amplitude [dB] of the transmitted signal and the reflected signal. The combined peak frequency of the transmitted signal is around 28.0 GHz, and the transmitted signal is obtained most efficiently at the target 28.0 GHz. However, since the port 2 (320) is in the open state, the level of the reflected signal rises as a whole. However, with respect to the target frequency of 28 GHz, a substantially flat characteristic can be obtained with an insertion loss of about 2.5 dB in a range of at least ± 1 GHz. Further, the insertion loss can be suppressed to less than 1 dB by optimizing the basic shape such as manufacturing variation and the coupling transmission line spacing of the parallel running portion 350.

According to the above configuration example, even if the terminating resistor 321 of the port 2 (320) is deleted, there is almost no influence such as deterioration on the transmission characteristics of the high frequency component, and by using the configuration of the circuit pattern within about 5 cm 28 A coupling circuit near 0.0 GHz can be easily configured. That is, stable coupling characteristics can be realized without the need for additional mounting components such as resistors, inductors, and capacitors, even in consideration of the shape for actual use, the impedance of the connection destination, and the like. As described above, a substantially flat frequency characteristic can be obtained with an insertion loss of about 1 dB in a range of at least ± 1 GHz with respect to the target frequency of 28 GHz.

(Example 5)
In the embodiment of FIGS. 1A, 2A, 3A, 4A, 5A and 6A, the copper foil pattern 1 (100) and the copper foil pattern 2 (200) are arranged in a straight line to form a parallel running portion. A coupling circuit 1000 including 350 was formed. However, in the present embodiment, it is also possible to meander the copper foil pattern 1 (100) and the copper foil pattern 2 (200) to form the parallel running portion 350. For example, a coupling circuit 1000 in which the copper foil pattern 1 (100) and the copper foil pattern 2 (200) meander to form a parallel running portion 350 is shown in FIG. 8A as Example 5. Also in FIG. 8A, the coaxial connector 311 mounted on the port 1 (310) at one end of the circuit board 300 is mounted across the port 1 left side connector mounting area 363 and the port 1 right side connector mounting area 364. By including such a configuration, it is possible to configure the configuration corresponding to the 28 GHz band, which is expected to be used in the fifth generation wireless communication.

The parameter values of the circuit board 300 and the coupling circuit 1000 shown in FIG. 8A are shown in Table 2 in the same manner as in FIGS. 3A, 4A, 5A and 6A, but only the coupling transmission line gap gap and the coupling transmission line length L are shown. different. That is, the combined transmission line spacing gap of FIGS. 3A, 4A, 5A and 6A is 0.2 mm, but the combined transmission line spacing gap of the coupling circuit 1000 shown in FIG. 8A is 0.1 mm. Further, the combined transmission line length L of FIGS. 3A, 4A, 5A and 6A is 37 mm, but the combined transmission line length L of the coupling circuit 1000 shown in FIG. 8A is about 30 mm. The transmission line width W of FIGS. 3A, 4A, 5A, 6A and 8A is 0.2 mm. The characteristic impedance of the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of FIG. 8A is also about 50Ω. In FIG. 8A, the combined transmission line length L forming the parallel running portion 350 is set to about 30 mm, and the parallel running portion 350 is meandered so that the port 1 (310) to the port 2 (320) or the port 4 (340). ) Is shortened. As a result, the size of the coupling circuit 1000 can be reduced. Further, even in the coupling circuit 1000 in which the coupling transmission line gap gap is shortened and the parallel running portion 350 meanders in this way, it is possible to exhibit good characteristics in the 28 GHz band as shown in FIG. 8B. .. A detailed description of FIG. 8B will be described later.

In FIG. 8A, the bending radius r when the parallel running portions 350 meander is set to 1 mm, and the distance between the adjacent parallel running portions 350 is set to 2 mm. For example, a detailed schematic diagram of the meandering portion 351a in FIG. 8A is shown in an enlarged view 352 of FIG. 8C. The coupling circuit 1000 of FIGS. 8C and 8A shows the same coupling circuit, and the enlarged view 352 of FIG. 8C is an enlarged schematic view of the meandering portion 351a. The bending radius r indicates the distance from the midpoint between the copper foil pattern 1 (100) and the copper foil pattern 2 (200) of the parallel running portion 350, and the distance between the parallel running portions 350 is the copper foil pattern 1 (100) and the copper foil. The distance from the midpoint of pattern 2 (200) to the midpoint is shown. Also in the meandering portion 351b and the meandering portion 351c in FIG. 8A, the bending radius r is set to 1 mm, and the distance between the adjacent parallel running portions 350 is set to 2 mm. Further, also in the meandering portion 351d, the meandering portion 351e, and the meandering portion 351f, the bending radius r is set to 1 mm, and the parallel running portion 350 is bent in the orthogonal direction. The meandering portion 351a, the meandering portion 351b, the meandering portion 351c, the meandering portion 351d, the meandering portion 351e, and the meandering portion 351f may be collectively referred to as the meandering portion 351.

As shown in FIG. 8A, when a coaxial connector 311 is mounted across the port 1 left side connector mounting area 363 and the port 1 right side connector mounting area 364 by providing a plurality of meandering parts 351 in the parallel running portion, the circuit The length of the substrate 300 can be shortened. That is, as shown in FIG. 8C, it is possible to shorten the length KW1 of the coupling circuit unit 600 composed of the parallel traveling units 350. The CW1 which is the width of the board end required for mounting the coaxial connector 311 which can be used in the 28 GHz band is about 12 mm, but according to the configuration of the parallel running portion 350 of FIGS. 8A and 8C, the coupling circuit portion 600 The length KW1 can be set to about 11 mm. In the embodiment of FIGS. 1A, 2A, 3A, 4A, 5A and 6A, the copper foil pattern 1 (100) and the copper foil pattern 2 (200) are arranged in a straight line, and the parallel running portion 350 is formed. Due to the formation, the length KW1 of the coupling circuit unit 600 was required to be about 37 mm. However, as shown in FIGS. 8A and 8C, the parallel running section 350 is shortened by shortening the coupling transmission line spacing gap, and the coupling circuit section 600 is provided by providing the parallel running section 350 with a plurality of meandering sections. It is possible to reduce the length of the meander by about 70%. Further, even the coupling circuit unit 600 reduced in this way can exhibit good characteristics in the 28 GHz band as shown in FIG. 8B.

FIG. 8B shows a transmission signal when a high-frequency AC signal is input to port 1 (310) of the coupling circuit of FIG. 8A, a DC signal is input to port 3 (330), and a superimposed signal is output from port 4 (340). It is a figure which showed the frequency characteristic of a reflected signal. The transmitted signal is a transmitted component of the high-frequency AC signal measured at port 4 (340), and the reflected signal is a reflected component of the high-frequency AC signal measured at port 1 (310). The horizontal axis of FIG. 8B is the frequency [GHz], and the vertical axis is the amplitude [dB] of the transmitted signal and the reflected signal. The combined peak frequency of the transmitted signal is around 28.0 GHz, and the transmitted signal is most efficiently obtained near the target 28.0 GHz. Further, the transmitted signal is attenuated by about 1.5 dB, which can be reduced to less than 1 dB by the above-mentioned optimization. Further, the reflected signal at the port 1 (310) is attenuated by about 18 dB, indicating that good characteristics can be realized. If the bending radius r is smaller than 0.5 mm, the reflected signal becomes large and the reflection characteristics tend to deteriorate. For example, when the bending radius r is smaller than 0.5 mm, the reflected signal may exceed about −10 dB, and practically, the bending radius r is preferably 0.5 mm or more.

Port 3 (330) will be described below. Port 3 (330) functions as a DC input unit for inputting a DC signal. A power supply device having a low output impedance is generally connected to a DC signal. Therefore, the output impedance of the device connected to the port 3 (330) is set to 1Ω. In this case, as described with reference to FIG. 4A, impedance mismatch is given to the AC component, so that the flatness of the frequency characteristic deteriorates. However, in FIG. 8A, in order to improve the deterioration of the flatness of the frequency characteristic, the inductor 410 is formed in the DC input portion of the port 3 (330) to improve the flatness of the frequency characteristic. That is, an inductor component having a spiral circuit pattern is generated on the circuit board side of the port 3 (330), and the impedance in the high frequency band is increased. Further, by setting the circuit pattern width of the inductor 410 to 0.1 mm, which is narrower than 0.2 mm of the parallel running portion 350, the characteristic impedance is increased and the inflow of high frequency components from the parallel running portion 350 is reduced. There is. By setting the circuit pattern width of the inductor 410 to 0.1 mm or less, the effect of reducing the inflow of high-frequency components from the parallel running portion 350 is further enhanced.

As a result, in the copper foil pattern 2 (200), only the impedance mismatch of the high frequency component is improved without affecting the DC component, and the flatness of the frequency response characteristic is improved. In this way, it is possible to realize stable coupling characteristics without adding components such as inductors and capacitors by considering the shape corresponding to the actual use described above and the impedance of the connection destination. Become.

As described above, FIG. 8C is a diagram including an enlarged view 352 of the meandering portion 351a of the coupling circuit 1000 of FIG. 8A. The coupling circuit 1000 of FIGS. 8C and 8A shows the same coupling circuit. As shown in FIG. 8C, the port 4 (340) can be provided with a region in which an optical element such as a laser or a light emitting diode can be mounted. Further, the width of the mounting portion of the coaxial connector 311 as the board end connector connected to the port 1 (310) is indicated by CW1. Further, FIG. 8C shows the length KW1 of the coupling circuit unit 600 configured by the parallel traveling unit 350.

As an example, the port 2 (320) of FIG. 8A may be formed with a terminating resistor of 50Ω connected or an inductor connected. As an example, the case where a 50Ω terminating resistor is connected to the port 2 (320) has already been described, so the details will be omitted. The form in which the inductor is connected to the port 2 (320) will be described below.

FIG. 9A shows a configuration in which the inductor 420 is connected to the port 2 (320). The inductor 420 can be formed on the back surface of the circuit board 300. The impedance near the target 28.0 GHz is about 50 Ω, and it is possible to form a value of about 0.37 nH of self-inductance. Further, the impedance of the inductor 420 at the frequency of the high frequency AC signal transmitting the copper foil pattern 1 (100) is preferably within ± 20% of the characteristic impedance of the copper foil pattern 2 (200).

FIG. 9B shows a configuration in which the inductor 440 is connected to the port 2 (320). The inductor 440 can be formed on the surface of the circuit board 300. That is, the inductor 440 can be formed on the same substrate surface as the substrate surface on which the parallel running portion 350 is formed. The impedance near the target 28.0 GHz is about 50 Ω, and it is possible to form a value of about 0.37 nH of self-inductance. Further, the impedance of the inductor 440 at the frequency of the high-frequency AC signal transmitting the copper foil pattern 1 (100) is preferably within ± 20% of the characteristic impedance of the copper foil pattern 2 (200).

(Mounting area for coaxial connectors, etc.)
FIG. 7A is a plan view of the coupling circuit of FIG. 5A. In the plan view of FIG. 7A, the area A101 (360) in which the coaxial connector 311 is mounted on the port 1 (310) and the area A102 (370) in which the coaxial connector 331 is mounted on the port 3 (330) are included. Further, in the plan view of FIG. 7A, the area C101 (390) in which the inductor 400 is formed is included. Further, in the plan view of FIG. 7A, the area A103 (380) in which the coaxial connector 341 is mounted on the port 4 (340) and the terminating resistor 321 is mounted on the port 2 (320) is included. A parallel running portion 350 extends over a length of 37 mm between the area A101 (360) and the area A103 (380). In the parallel running portion 350, the copper foil pattern 1 (100) having a width of 0.2 mm and the copper foil pattern 2 (200) run in parallel with a coupling transmission line spacing of 0.2 mm.

FIG. 7B is an enlarged view of area A103 (380). In the area A103 (380), the coaxial connector 341 mounted on the port 4 (340) is mounted across the port 4 connector mounting area 1 (381) and the port 4 connector mounting area 2 (382). The copper foil pattern 2 (200) extends between the port 4 connector mounting area 1 (381) and the port 4 connector mounting area 2 (382) to the end of the circuit board 300. Further, the terminating resistor 321 connecting the port 2 (320) and the ground 500 is mounted in the terminating resistor mounting area 383.

FIG. 7C is an enlarged view of area A101 (360). In the area A101 (360), the coaxial connector 311 mounted on the port 1 (310) is mounted across the port 1 connector mounting area 1 (361) and the port 1 connector mounting area 2 (362). The copper foil pattern 1 (100) extends between the port 1 connector mounting area 1 (361) and the port 1 connector mounting area 2 (362) to the end of the circuit board 300. The copper foil pattern 2 (200) bends toward the area C101 (390) where the inductor 400 is formed. In FIG. 7C, the copper foil pattern 2 (200) bends at a substantially right angle toward area C101 (390).

FIG. 7D is an enlarged view of the area C101 (390) in which the inductor 400 is formed. The inductor 400 is formed by spirally wiring a copper foil pattern 2 (200). The radius of the inductor 400 shown in FIG. 7D is about 5 mm, and the distance from the winding start to the winding end of the copper foil pattern 2 (200) is about 4 mm. The impedance near the target 28.0 GHz is about 50 Ω, and it is possible to form a value of about 0.37 nH of self-inductance. Further, no ground is formed on the back surface of the circuit board 300 corresponding to the region where the inductor 400 of the area C101 (390) is formed. Therefore, through holes are formed at the start and end of winding of the copper foil pattern 2 (200), and by providing the circuit pattern on the back surface of the circuit board 300, the start and end of winding of the copper foil pattern 2 (200) are connected. Has been done.

FIG. 7E is an enlarged view of the area A102 (370). In the area A102 (370), the coaxial connector 331 mounted on the port 3 (330) is mounted across the port 3 connector mounting area 1 (371) and the port 3 connector mounting area 2 (372). The copper foil pattern 2 (200) extends between the port 3 connector mounting area 1 (371) and the port 3 connector mounting area 2 (372) to the end of the circuit board 300.

In the above embodiment, the variation in the characteristic impedance of each component is within ± 20%. Further, the impedances of the terminating resistor 321 and the inductor 400 at the frequency of the high-frequency AC signal transmitting the copper foil pattern 1 (100) or the coupling peak frequency are included within ± 20% of the variation in the characteristic impedance of each component.

The coupling circuit of FIG. 5A on which the coaxial connectors 311, 331, 341 and the terminating resistor 321 are mounted has additional mounting components such as an inductor and a capacitor in consideration of the shape for actual use and the impedance of the connection destination. Stable coupling characteristics can be realized without the need. That is, it is possible to obtain a substantially flat frequency characteristic with an insertion loss of about 1 dB in a range of at least ± 1 GHz with respect to the target frequency of 28 GHz.

(Modification example 1)
In the above-described embodiment, the light emitting element is assumed as the device connected to the port 4 (340) of the circuit board 300, but the above description also occurs when the device connected to the port 4 (340) is the light receiving element. The principle of the above embodiment can be applied. That is, when the light receiving element is connected to the port 4 (340), the high frequency AC signal is input to the port 4 (340) as the output signal of the light receiving element, transmitted through the parallel running portion 350, and the transmitted signal is transmitted to the port. It is output from 1 (310). The characteristics of the transmitted signal and the reflected signal in the parallel running portion 350 in this case are shown in FIGS. 3B, 4B, 5B, 6B and 8B. Further, since the DC signal input to the port 3 (330) is used as a signal that defines the bias of the light receiving element, the DC signal is output from the port 4 (340).

(Modification 2)
In the above-described embodiment, the configuration in which the copper foil pattern 1 (100) and the copper foil pattern 2 (200) are wired to the circuit board 300 has been described. However, as long as the copper foil patterns are close to each other as a substrate material or a substrate form, the application is not limited to a printed circuit board, and may be applied to, for example, an electric wire, a molded resin circuit component (MID: Molded Interconnect Device), or the like. In the case of electric wires, two electric wires running in parallel correspond to the parallel running portion 350 of the copper foil pattern 1 (100) and the copper foil pattern 2 (200), and a ground electric wire is provided outside the two electric wires. Two more can be arranged. It may also be realized by a shielded electric wire. In this case, it is possible to use a metal foil or a braid which is a conductor wound around the outer cover of the two-wire shielded electric wire as a ground.

(Modification example 3)
In the above-described embodiment, a configuration in which only one parallel running portion 350 is provided has been described. However, a plurality of parallel running units 350 may be provided, and signals having different frequencies may be used as transmission signals in each of the parallel running parts 350. As described with reference to FIG. 2B, if the coupling transmission line spacing is different in each parallel running portion 350, the coupling peak frequency is also different. Further, as described with reference to FIG. 2F, if the coupling transmission line length is different in each parallel running portion 350, the coupling peak frequency is also different. Further, the coupling peak frequency also changes even if the values of other parameters different from the coupling transmission line spacing and the coupling transmission line length in Table 1 are changed. It is also possible to adopt a configuration in which the coupling circuit 1000 is provided with a plurality of parallel running portions 350 in which these parameters are changed.

FIG. 10 shows an example in which the coupling circuit 1000 adopts a configuration in which a plurality of parallel running portions 350 are provided. A signal S1 having various frequency components is input to the coupling circuit unit 600, a low frequency signal S4 in an arbitrary low frequency band is transmitted through the parallel running unit 350a, and a high frequency signal S3 in an arbitrary high frequency band is transmitted through the parallel running unit 350b. Is transmitted, and a passing component is generated as a passing signal S2. By adopting a configuration in which a plurality of parallel running portions 350 are provided in this way, it is possible to generate signals of various frequencies or frequency bands by a plurality of coupling frequencies.

(Modification example 4)
In the above-described embodiment, the case where the terminating resistor 321 is mounted on the port 2 (320) has been mainly described, but as shown in FIG. 6A, the basic configuration is such that the terminating resistor 321 is not mounted on the port 2 (320). It is also possible to. That is, in the coupling circuit of FIGS. 3A and 4A, the terminating resistor 321 may not be mounted on the port 2 (320). Even in this case, stable coupling characteristics should be realized without the need for additional mounting components such as resistors, inductors and capacitors, taking into consideration the shape for actual use and the impedance of the connection destination. Can be done. That is, even if the terminating resistor 321 is not mounted on the port 2 (320), a substantially flat frequency characteristic can be obtained with an insertion loss of about 1 dB in a range of at least ± 1 GHz with respect to the target frequency of 28 GHz. ..

(Modification 5)
In the above-described embodiment, the electric signal applied to the port 3 (330) has been described as a direct current, but in the present embodiment, the electric signal applied to the port 3 (330) is not limited to the direct current. That is, if the frequency is different from the frequency of the high-frequency AC signal applied to the port 1 (310) or the port 4 (340), it can be set as the frequency of the electric signal applied to the port 3 (330). ..

The features of the coupling circuit 1000 of this embodiment will be described below.

In the coupling circuit 1000 according to the first aspect of the present invention, the first conductor and the second conductor run in parallel at predetermined intervals, and the first conductor and the second conductor run in parallel. It is preferable to include a parallel running portion 350 having a meandering portion 351 that the body meanders. Further, the coupling circuit 1000 forms a third conductor that forms a ground for an electric signal transmitted by the first conductor and a third conductor that forms a ground for an electric signal transmitted by the second conductor. It preferably contains a fourth conductor that is connected to the conductor. It is preferable that an electric signal is transmitted between the first conductor and the second conductor in the parallel running portion 350 of the coupling circuit 1000. In the parallel running portion 350, the first electric signal transmitted by the first conductor is transmitted to the second conductor in the same direction as the transmission direction of the first conductor, and is transmitted to the second conductor by the second conductor. It is preferable that a second electric signal having a frequency different from that of the first electric signal is applied.

According to the above configuration, no inductor or capacitor is required, and by having a meandering portion having a small bending radius provided on the circuit board, a conductor such as a miniaturized transmission line pattern and a terminating resistor are sufficient to generate a direct current. It is possible to combine high frequency alternating current.

The bending radius of the meandering portion 351 according to the second aspect of the present invention is such that the first electric signal input from the port 1 (310), which is one end portion of the first conductor, is the terminal portion of the first conductor. It is preferably determined by the amount of reflection when the light is reflected from the port 2 (320) to one end. The bending radius is preferably in a range in which the amount of reflection does not exceed a predetermined value.

According to the above configuration, the coupling circuit 1000 can be miniaturized by using a transmission line pattern that is miniaturized by having a meandering portion having a small bending radius.

The distance between the first conductor and the second conductor of the parallel running portion 350 according to the third aspect of the present invention is such that the length of the parallel running portion 350 is shorter than the predetermined coupling peak frequency. It is preferable that the frequency is set to be. The coupling peak frequency is preferably the frequency at which the amplitude attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest.

According to the above configuration, the coupling circuit 1000 is used by using a transmission line pattern that is miniaturized by narrowing the distance between the first conductor and the second conductor and reducing the width of the parallel running portion 350. Can be miniaturized.

In the coupling circuit 1000 according to the fourth aspect of the present invention, the first conductor located on the side opposite to the port 1 (310) which is one end of the first conductor to which the first electric signal is applied. It is preferable that a terminating resistor 321 is connected to the port 2 (320) which is the terminal portion of the above. The characteristic impedance of the terminating resistor 321 has a value within ± 20% of the value of the characteristic impedance formed by the first conductor and the third conductor, and is the terminal portion of the port 2 (320) and the third. It is preferable to be connected to the conductor of 3.

According to the above configuration, the end portion of the first conductor can be matched with the characteristic impedance of the first conductor. Therefore, the influence of the reflection of the first electric signal transmitted by the first conductor is reduced, and the frequency characteristic when the first electric signal is transmitted can be improved.

In the coupling circuit 1000 according to the fifth aspect of the present invention, the first conductor located on the opposite side of the port 1 (310), which is one end of the first conductor to which the first electric signal is applied. It is preferable that the inductors 420 and 440 are connected to the port 2 (320) which is the terminal portion of the above. The characteristic impedance of the inductors 420 and 440 has a value within ± 20% of the value of the characteristic impedance formed by the first conductor and the third conductor, and is connected to the port 2 (320) which is the terminal portion. It is preferable that it is connected to a third conductor.

According to the above configuration, the end portion of the first conductor can be matched with the characteristic impedance of the first conductor. Therefore, the influence of the reflection of the first electric signal transmitted by the first conductor is reduced, and the frequency characteristic when the first electric signal is transmitted can be improved.

In the coupling circuit 1000 according to the sixth aspect of the present invention, it is preferable that the coupling peak frequency of the first electric signal becomes higher as the parallel portion 350 of the first conductor and the second conductor becomes shorter. The coupling peak frequency is preferably the frequency at which the amplitude attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest.

According to the above configuration, the coupling peak frequency of the first electric signal transmitted through the parallel running portion 350 can be made variable. In particular, the shorter the length of the parallel running portion 350, the higher the coupling peak frequency. Therefore, in a coupling circuit that handles a high frequency, it becomes possible to use an effective method for miniaturizing the coupling circuit.

In the coupling circuit 1000 according to the seventh aspect of the present invention, the narrower the distance between the first conductor and the second conductor in the parallel running portion 350 of the first conductor and the second conductor, the narrower the distance between the first conductor and the second conductor. It is preferable that the coupling peak frequency of the electric signal of 1 is low. The coupling peak frequency is preferably the frequency at which the amplitude attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest.

According to the above configuration, the coupling peak frequency of the first electric signal transmitted through the parallel running portion 350 can be made variable. In particular, when it is necessary to keep the distance between the conductors of the parallel running portion 350 narrow, the manufacturing variation becomes large, but since it is not necessary to keep the distance between the conductors of the parallel running portion 350 narrower than necessary, the manufacturing variation becomes large. It is possible to keep the fluctuation of the coupling peak frequency due to.

The coupling circuit 1000 according to the eighth aspect of the present invention preferably further includes a circuit board 300. The first conductor and the second conductor are wirings formed on the front surface of the circuit board 300, and the third conductor and the fourth conductor are grounds 500 formed on the back surface of the circuit board 300. Is preferable.

According to the above configuration, since the coupling circuit 1000 can be realized by the circuit board 300 and the circuit pattern, the mounting components such as capacitors and operational amplifiers can be reduced, the component cost and the mounting cost can be reduced, and the device can be significantly reduced in size. It becomes possible.

The coupling circuit 1000 according to the ninth aspect of the present invention is an inductor in which a second conductor is spirally formed in a port 3 (330), which is one end of a second conductor into which a second electric signal is input. It is preferable to form 410 and 430. The impedance of the inductors 410 and 430 at the frequency of the first electric signal is preferably within ± 20% of the characteristic impedance formed by the second conductor and the fourth conductor.

According to the above configuration, even if a power supply device having a low output impedance or the like is connected, it is possible to maintain good frequency characteristics for a high-frequency AC signal simply by forming an inductor according to a circuit pattern.

In the coupling circuit 1000 according to the tenth aspect of the present invention, it is preferable that one end of the first conductor is port 1 (310) and the end of the first conductor is port 2 (320). Further, it is preferable that one end of the second conductor is port 3 (330) and the end of the second conductor is port 4 (340). It is preferable that the first electric signal input to the port 1 (310) is output from the port 4 (340), and the second electric signal is output from the port 3 (330) to the port 4 (340). Coaxial connectors 311, 331, and 341 for transmitting and receiving a first electric signal and a second electric signal to and from an external device are mounted on port 1 (310), port 3 (330), and port 4 (340), respectively. Is preferable.

According to the above configuration, it is possible to reduce the number of mounted components such as a capacitor and an operational amplifier even in a form in which a connector for transmitting and receiving a first electric signal and a second electric signal is mounted on a coupling circuit. Therefore, not only the component cost and the mounting cost can be reduced, but also the device can be significantly miniaturized.

Although the embodiments have been described in detail with reference to the drawings, the present invention is not limited to the contents described in the above embodiments. In addition, the components described above include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described above can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

100 copper foil pattern 1
200 copper foil pattern 2
300 circuit board 310 port 1
311 port 1 connector 320 port 2
321 Termination resistor 330 Port 3
331 port 3 connector 340 port 4
341 Port 4 connector 350 Parallel running part 351 Meandering part 360 Area A101
361 Port 1 Connector mounting area 1
362 Port 1 Connector mounting area 2
370 area A102
371 Port 3 Connector mounting area 1
372 Port 3 Connector mounting area 2
380 area A103
381 Port 4 Connector mounting area 1
382 port 4 connector mounting area 2
383 Termination resistor mounting area 390 Area C101
400 Inductor 500 Ground 600 Coupling circuit 1000 Coupling circuit

Claims (10)

A parallel running portion in which the first conductor and the second conductor run in parallel at predetermined intervals, and the first conductor running in parallel and the second conductor meandering in a meandering portion. ,
With the third conductor forming the ground of the electric signal transmitted by the first conductor,
A fourth conductor connected to the third conductor, which forms a ground for an electric signal transmitted by the second conductor, and the first conductor in the parallel running portion. In a coupling circuit in which an electric signal is transmitted between the second conductors,
In the parallel running portion, the first electric signal transmitted by the first conductor is transmitted to the second conductor in the same direction as the transmission direction of the first conductor.
A coupling circuit in which a second electric signal having a frequency different from that of the first electric signal is applied to the second conductor. With respect to the bending radius of the meandering portion in the parallel running portion, the first electric signal input from one end portion of the first conductor is reflected from the terminal portion of the first conductor to the one end portion. The coupling circuit according to claim 1, wherein the amount of reflection in the case is a bending radius in a range not exceeding a predetermined value. The distance between the first conductor and the second conductor of the parallel running portion is set so that the length of the parallel running portion is shorter than the predetermined coupling peak frequency. The coupling circuit according to claim 1 or 2, wherein the coupling peak frequency is a frequency at which the amplitude attenuation of the first electric signal transmitted between the first conductor and the second conductor is the smallest. The first conductor and the third conductor are located at the end of the first conductor located on the side opposite to one end of the first conductor to which the first electric signal is applied. Any one of claims 1 to 3 in which a terminating resistor having a value within ± 20% of the value of the characteristic impedance formed by the body is connected between the terminal portion and the third conductor. The coupling circuit according to one item. The first conductor and the third conductor are located at the end of the first conductor located on the side opposite to one end of the first conductor to which the first electric signal is applied. Any one of claims 1 to 3 in which an inductor having a value within ± 20% of the value of the characteristic impedance formed by the body is connected between the terminal portion and the third conductor. The coupling circuit described in the section. The shorter the parallel portion of the first conductor and the second conductor, the higher the coupling peak frequency of the first electric signal, and the coupling peak frequency of the first conductor and the first conductor. The coupling circuit according to any one of claims 1 to 5, wherein the frequency at which the amplitude attenuation of the first electric signal transmitted to and from the conductor 2 is the smallest. The narrower the distance between the first conductor and the second conductor in the parallel running portion of the first conductor and the second conductor, the closer the coupling peak frequency of the first electric signal becomes. Any of claims 1 to 6, wherein the coupling peak frequency becomes lower and the attenuation of the amplitude of the first electric signal transmitted between the first conductor and the second conductor is the smallest. The coupling circuit according to one item. Including the circuit board
The first conductor and the second conductor are wirings formed on the surface of the circuit board.
The coupling circuit according to any one of claims 1 to 7, wherein the third conductor and the fourth conductor are grounds formed on the back surface of the circuit board. An inductor in which the second conductor is spirally formed is formed at an input portion of the second conductor into which the second electric signal is input, and the impedance of the inductor at the frequency of the first electric signal is The coupling circuit according to any one of claims 1 to 8, wherein the characteristic impedance formed by the second conductor and the fourth conductor is within ± 20%. One end of the first conductor is port 1, the end of the first conductor is port 2, one end of the second conductor is port 3, and the end of the second conductor. When the unit is port 4, the first electric signal input to the port 1 is output from the port 4, and the second electric signal is output from the port to the port 4.
Any of claims 1 to 9, wherein an external device and a connector for transmitting and receiving the first electric signal and the second electric signal are mounted on the port 1, the port 3, and the port 4, respectively. The coupling circuit according to one item.

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