circuit board

Abstract

To provide a circuit board that can reduce signal degradation. [Solution] The circuit board 100 of the present disclosure comprises a wiring board 101, a connector 103 mounted on the wiring board 101 having a main terminal and a sub terminal, a power supply circuit mounted on the wiring board 101 having an input terminal and an output terminal, a signal circuit mounted on the wiring board 101 having a first terminal and a second terminal, and a signal transmitting and receiving circuit 102 mounted on the wiring board 101 having a power terminal and a signal terminal, wherein the main terminal and the sub terminal penetrate the wiring board 101, and the wiring board 101 has a first wire 104 connecting the main terminal and the input terminal, a second wire 105 connecting the input terminal and the first terminal without going through the main terminal, a third wire 108 connecting the output terminal and the power terminal, and a fourth wire 107 connecting the second terminal and the signal terminal, wherein the second wire 105 passes between the main terminal and the sub terminal.

Description

Technical Field

[0001] This disclosure relates to a circuit board.

[0002] Between two semiconductor devices mounted on an electronic device, data communication is performed using digital signals. The digital signals are transmitted via wirings and cables mounted on a circuit board. The circuit board and the cable are connected via a connector. In recent years, for the simplification of the system of electronic devices, a method of superimposing and transmitting the signals transmitted and received by a semiconductor element and the DC power supply for driving the semiconductor element on one cable has been adopted. For example, in Patent Document 1, a technique is disclosed in which a signal and a power supply transmitted through one coaxial cable are separated in a signal-power separation circuit mounted on a circuit board and supplied to the signal terminal and the power supply terminal of a semiconductor element, respectively.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there is a risk of signal degradation between the signal terminal of the semiconductor element and the signal terminal of the coaxial connector.

Means for Solving the Problems

[0005] The circuit board according to this disclosure comprises a wiring board, a connector mounted on the wiring board having a main terminal and a sub-terminal, a power supply circuit mounted on the wiring board having an input terminal and an output terminal, a signal circuit mounted on the wiring board having a first terminal and a second terminal, and a signal transmitting and receiving circuit mounted on the wiring board having a power terminal and a signal terminal, wherein the main terminal and the sub-terminal penetrate the wiring board, and the wiring board has a first wire connecting the main terminal and the input terminal, a second wire connecting the input terminal and the first terminal without going through the main terminal, a third wire connecting the output terminal and the power supply terminal, and a fourth wire connecting the second terminal and the signal terminal, wherein the second wire passes between the main terminal and the sub-terminal. [Effects of the Invention]

[0006] According to this disclosure, a circuit board capable of reducing signal degradation is provided. [Brief explanation of the drawing]

[0007] [Figure 1A] This is a top view showing a circuit board according to the first embodiment. [Figure 1B] This is a cross-sectional view of the circuit board shown in Figure 1A, along line AA'. [Figure 1C] This is a top view showing Embodiment 2 of the circuit board according to the first embodiment. [Figure 1D] This is a top view showing Embodiment 3 of the circuit board according to the first embodiment. [Figure 1E] This is a top view showing Embodiment 4 of the circuit board according to the first embodiment. [Figure 1F] This is a top view showing Embodiment 5 of the circuit board according to the first embodiment. [Figure 2] This is a top view showing a comparative example of a circuit board according to the first embodiment. [Figure 3A] This figure shows the simulation results of the reflection characteristics of the circuit board according to the first embodiment in Example 1 and in comparative examples. [Figure 3B]This figure shows the reflection characteristics of the circuit board according to the first embodiment in Example 2-5. [Figure 4] This is a top view showing a circuit board according to the second embodiment. [Figure 5] This figure shows the simulation results of the reflection characteristics in an embodiment and comparative example of the circuit board according to the second embodiment. [Modes for carrying out the invention]

[0008] The embodiments for implementing this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments described below and can be modified as appropriate without departing from its essence. Furthermore, in the drawings described below, components having the same function will be denoted by the same reference numerals, and their descriptions may be omitted or simplified.

[0009] [First Embodiment] Figure 1A is a top view showing the circuit board 100 according to this embodiment. Figure 1B is a cross-sectional view of the circuit board 100 shown in Figure 1A along line AA'. Figures 1C, 1D, 1E, and 1F are top views showing embodiments of the circuit board 100 shown in Figure 1A.

[0010] The circuit board 100 is, for example, a printed circuit board. The circuit board 100 includes a printed wiring board 101, a signal transmitting / receiving circuit 102, a coaxial connector 103, a first signal filter (power supply circuit) 110, a second signal filter (power supply circuit) 111, a DC-DC converter (power supply circuit) 112, a capacitor (signal circuit) 113, and a resistor (signal circuit) 114. The signal transmitting / receiving circuit 102 is a semiconductor element. The signal transmitting / receiving circuit 102 has a signal terminal (not shown) for transmitting and receiving signals and a terminal (not shown) for receiving power from an external source. The coaxial connector 103 has a signal terminal 103a (main terminal), a ground terminal 103b (sub-terminal), and a main body (not shown). The main body of the coaxial connector 103 is the part to which the coaxial cable is connected. In this embodiment, the coaxial connector 103 also has four ground terminals 103b. The signal terminal 103a is surrounded by four ground terminals 103b on the same plane.

[0011] The first signal filter 110 and the second signal filter 111 are, for example, coils or ferrite beads. The signal transmitting / receiving circuit 102, capacitor 113, resistor 114, first signal filter 110, second signal filter 111, and DC-DC converter 112 are mounted on one main surface of the printed circuit board 101 (hereinafter referred to as the "first mounting surface"). The main body of the coaxial connector 103 (the part that connects to the coaxial cable) is located on the second mounting surface side, opposite to the first mounting surface on which the signal transmitting / receiving circuit 102 is mounted. As shown in Figure 1B, the signal terminal 103a and ground terminal 103b penetrate the printed circuit board 101 from the second mounting surface toward the first mounting surface and protrude in the Z direction from the first mounting surface. In other words, the coaxial connector 103 is inserted and mounted from the second mounting surface side. The signal terminal 103a and ground terminal 103b may be soldered to the first mounting surface.

[0012] Next, the circuit connection structure will be explained. The signal terminal 103a of the coaxial connector 103 is connected to one end of the first signal filter 110 (the input terminal of the signal circuit) via wiring (first wiring) 104 on the first mounting surface. One end of the first signal filter 110 is connected to one end of the capacitor 113 (the first terminal of the signal circuit) via wiring (second wiring) 105 provided on the first mounting surface. In a plan view of the printed circuit board 101 (XY plane in the figure), wiring 105 passes between the signal terminal 103a of the coaxial connector 103 and one of the four ground terminals 103b. The length of wiring 104 is shorter than the length of wiring 105. Wiring 105 does not pass between the remaining three ground terminals 103b (other sub-terminals) and the signal terminal 103a.

[0013] The other end of the first signal filter 110 is connected to one end of the second signal filter 111. The other end of the second signal filter 111 is connected to one end of the DC-DC converter 112. The other end of the DC-DC converter 112 (output terminal of the power supply circuit) is connected to the power supply terminal of the signal transmission / reception circuit 102 via wiring 108 (third wiring). The ground terminal 103b of the coaxial connector 103 is connected to the ground (not shown) of the printed circuit board 101. The other end of the capacitor 113 is connected to one end of the resistor 114 via wiring 106. The other end of the resistor 114 (second terminal of the signal circuit) is connected to the signal terminal of the signal transmission / reception circuit 102 via wiring 107 (fourth wiring). The terminals of the capacitor 113 and the terminals of the resistor 114 are soldered to the first mounting surface. Because the resistor 114 is placed near one end (signal terminal) of the signal transmission / reception circuit 102, the sum of the input impedance of the signal transmission / reception circuit 102 and the resistance value of the resistor 114 matches the characteristic impedance of the wiring 106.

[0014] In this embodiment, considering the dimensions of the first signal filter 110, the first signal filter 110 is disposed outside the region surrounded by the plurality of ground terminals 103b of the coaxial connector 103. That is, in a plan view of the printed wiring board 101, the distance between the signal terminal 103a and one end of the first signal filter 110 is longer than the distance d1 between the signal terminal 103a and the ground terminal 103b. Such an arrangement structure is suitable when the dimensions of the first signal filter 110 are large and the first signal filter 110 cannot be disposed within the region surrounded by the ground terminals 103b. In addition, the first signal filter 110 can also be disposed outside the region surrounded by the plurality of ground terminals 103b when preventing a short circuit between the first signal filter 110 and the ground terminal 103b due to a mounting defect.

[0015] Subsequently, the operation of the circuit will be described. When a coaxial cable (not shown) is connected to the connection portion of the coaxial connector 103, a signal and a DC power supply are transmitted from an external device (not shown) to the circuit board 100 via the coaxial cable. The signal and the DC power supply that reach the coaxial connector 103 are transmitted to the wiring 104 provided on the first mounting surface via the signal terminal 103a. The signal and the DC power supply transmitted to the wiring 104 are separated by the first signal filter 110, the second signal filter 111, and the capacitor 113.

[0016] The first signal filter 110 is connected to the wiring 104 and has a first cut-off frequency. The second signal filter 111 is connected to the first signal filter 110 and has a second cut-off frequency lower than the first cut-off frequency. The DC-DC converter 112 is connected to the second signal filter 111 and outputs a power supply voltage to the power supply terminal of the signal transmission / reception circuit 102.

[0017] Since the first signal filter 110 has the characteristics of a low-pass filter, high-frequency signals are transmitted to the wiring 105 without passing through the first signal filter 110 and reach the capacitor 113. Also, the capacitor 113 is in a short-circuit state with respect to high-frequency signals. Therefore, the high-frequency signals reach the signal terminal of the signal transmission / reception circuit 102 via the wiring 106, the resistor 114, and the wiring 107 from the capacitor 113. Here, the sum of the input impedance of the signal transmission / reception circuit 102 and the resistance value of the resistor 114 is matched with the characteristic impedance of the wiring 106. Therefore, no reflection of high-frequency signals occurs.

[0018] Also, the signal output from the signal terminal of the signal transmission / reception circuit 102 reaches one end of the first signal filter 110 via the wiring 107, the resistor 114, the wiring 106, the capacitor 113, and the wiring 105. Since the first signal filter 110 has the characteristics of a low-pass filter, high-frequency signals are transmitted to the wiring 104 without passing through the first signal filter 110 and are transmitted to the signal terminal 103a of the coaxial connector 103. The signal that reaches the coaxial connector 103 is transmitted to an external device via a coaxial cable.

[0019] Since the first signal filter 110 has a high impedance with respect to high-frequency signals, the wirings and components connected to the other end side of the first signal filter 110 do not become stubs. Therefore, the signals output or received by the signal transmission / reception circuit 102 are not affected by reflection.

[0020] The second signal filter 111 operates when the frequency band of the signal output by the signal transmission / reception circuit 102 and the frequency band of the signal input to the signal transmission / reception circuit 102 are different. With a single signal filter, there is a risk that it will not be able to maintain a high impedance for different frequency bands for transmission and reception. To shorten the stub, the first signal filter 110, which is located close to the signal terminal 103a, operates for high-frequency signals. The second signal filter 111 operates for low-frequency signals. In this case, the low-frequency signal may pass through the first signal filter 110. That is, the impedance of the first signal filter 110 is higher than that of the second signal filter 111 for high-frequency signals. Conversely, the impedance of the second signal filter 111 is higher than that of the first signal filter 110 for low-frequency signals.

[0021] The DC power transmitted through wiring 104 passes through the first signal filter 110 and the second signal filter 111, which are low-pass filters, and reaches the DC-DC converter 112. Also, since wiring 105 is connected to capacitor 113, it is isolated from the DC power. That is, the DC power is not transmitted through wiring 105 and does not reach the signal terminals of the signal transmission / reception circuit 102. The DC power passes through the first signal filter 110 and the second signal filter 111 and reaches the DC-DC converter 112. The DC power is converted by the DC-DC converter 112 to the power supply voltage required by the signal transmission / reception circuit 102 and reaches the power terminals of the signal transmission / reception circuit 102 via wiring 108.

[0022] In electronic devices, to minimize high-frequency signal loss, it is effective to connect the signal terminal of a semiconductor element to the signal terminal of a coaxial connector using the shortest possible path. However, there may be insufficient space to mount a signal-power isolation circuit on the shortest straight line connecting the signal terminal of the semiconductor element to the signal terminal of the coaxial connector. In such cases, the signal-power isolation circuit needs to be positioned off the straight line connecting the signal terminal of the semiconductor element to the signal terminal of the coaxial connector. As a result, the wiring connecting the main signal wiring of the high-frequency signal and the signal-power isolation circuit becomes longer, and this wiring acts as a stub, causing signal reflection. In contrast, according to the circuit board 100 of this embodiment, there is no stub that reflects the high-frequency signal, thus reducing signal degradation.

[0023] Next, we will describe Examples 1-5 of the circuit board 100 shown in Figures 1A and 1B. Note that Examples 2-5 are modified versions of Example 1.

[0024] (Example 1) Example 1 of the circuit board 100 shown in Figure 1A will be described. The printed circuit board 101 of Example 1 is a laminated substrate consisting of 6 layers. The thicknesses of the conductor layers 1 to 6 in the printed circuit board 101 are 0.031 mm, 0.031 mm, 0.034 mm, 0.031 mm, and 0.031 mm, respectively. The material of the conductor layers is, for example, copper. An insulating layer is provided between adjacent conductor layers. The thickness of each insulating layer is 0.08 mm between the 1st and 2nd layers, 0.08 mm between the 2nd and 3rd layers, 0.964 mm between the 3rd and 4th layers, 0.08 mm between the 4th and 5th layers, and 0.08 mm between the 5th and 6th layers. The dielectric constant is 4.3 and the dielectric loss tangent is 0.02. The material of the insulating layer is, for example, glass epoxy resin. Solder resist is applied to the 1st and 6th layers. The thickness of the solder resist in the first and sixth layers is 0.03 mm. The dielectric constant is 3.0, and the dielectric loss tangent is 0.02. The overall thickness of the printed circuit board 101 is 1.536 mm.

[0025] The coaxial connector 103 has four ground terminals 103b. The four ground terminals 103b are arranged at the four corners of a square. The arrangement pitch of the ground terminals 103b is 5.08 mm. The signal terminal 103a is located at the intersection of the diagonals of the four ground terminals 103b. The distance d1 between the signal terminal 103a and the ground terminal 103b is 2.54 mm. The characteristic impedance of the coaxial connector 103 is 75 Ω. The length of wire 104 is 3.5 mm. The length of wire 105 is 4.6 mm. The length of wire 106 is 3.0 mm. The length of wire 107 is 1.7 mm. The width of each wire 104, wire 105, wire 106, and wire 107 is 0.35 mm. The characteristic impedance of wires 106 and 107 is 75 Ω. The printed circuit board 101 has no conductors except for the parts that are in contact with wiring 104, wiring 105, signal terminal 103a, and ground terminal 103b, within a concentric circle with a radius of 3 mm centered on the signal terminal 103a of the mounted coaxial connector 103. The areas within the concentric circle where no conductors are present are filled with an insulator.

[0026] In this embodiment, the first signal filter 110 is a ferrite bead. The impedance of the first signal filter 110 at 1 GHz is 400 Ω. The second signal filter 111 is a coil (inductor). The inductance of the second signal filter 111 is 10 μH. The capacitance of the capacitor 113 is 0.1 μF. The resistance of the resistor 114 is 6.8 Ω. The impedance of the signal terminal 103a of the signal transmitting / receiving circuit 102 is 70 Ω. The sum of the impedance of the signal terminal 103a and the resistance of the resistor 114 is 76.8 Ω, which is approximately matched with the characteristic impedance of the wiring 106, which is 75 Ω.

[0027] Figure 2 is a top view showing a comparative example of the circuit board 100 according to the first embodiment. The layer configuration, component positions, and constants of the printed circuit board 101 in the comparative example are the same as in Example 1. The difference between the comparative example and Example 1 is that there is no wiring 105, and wiring 120 connects the signal terminal 103a of the coaxial connector 103 to one end of the capacitor 113. In the comparative example, wiring 104 acts as a stub for high-frequency signals. The length of wiring 120 is 3 mm. The width of wiring 120 is 0.35 mm. The lengths of wiring 104 and wiring 106 are the same as in Example 1.

[0028] Figure 3A shows the simulation results of the reflection characteristics of Example 1 and the comparative example. The vertical axis represents the return loss (dB). The horizontal axis represents the frequency (Hz). The reflection characteristics are measured by the following method. First, when a coaxial cable is connected to the coaxial connector 103, the network analyzer (not shown) injects a sine wave signal into the circuit board 100 while sweeping the frequency. Then, the injected sine wave signal is reflected by the circuit board 100 and returns to the network analyzer. The network analyzer measures the amount of reflection for each frequency. The ratio of the amount of reflection to the amount of injection is the return loss (dB). The smaller the value of the return loss, the smaller the amount of reflection. In the simulation, the S-parameters (S11) as seen from the signal terminal 103a of the coaxial connector 103 were calculated, and the reflection characteristics (return loss) were obtained from these calculated values. Ansys's HFSS was used as the simulator.

[0029] In Figure 3A, the dashed line C shows the return loss of the comparative example. The solid line E1 shows the return loss characteristics of Example 1. Comparing the return losses at 6.25 GHz, the return loss in the comparative example with a stub is -3.2 dB. In contrast, the return loss in Example 1 without a stub is -10.6 dB. That is, the reflection in Example 1 is smaller than the reflection in the comparative example. In Example 1 without a stub, the signal that reaches the first signal filter 110 is transmitted to wiring 105 without returning to signal terminal 103a. In contrast, in the comparative example, wiring 104 and wiring 120 extend from signal terminal 103a of the coaxial connector 103. The high-frequency signal transmitted to wiring 104 is reflected by the first signal filter 110 and returns to signal terminal 103a, so the reflected wave is superimposed on the signal transmitted to wiring 120. Therefore, the return loss in the comparative example is larger than the return loss in Example 1.

[0030] The CoaXPress (CXP) standard specifies acceptable return loss values ​​for each frequency. When the maximum signal transmission speed of the device circuit is 12.5 Gbps, the acceptable values ​​are -10 dB or less for 5 MHz to 625 MHz, -7 dB or less for 625 MHz to 3.2 GHz, and -4 dB or less for 3.2 GHz to 6.25 GHz.

[0031] (Example 2) Figure 1C is a top view showing Example 2 of the circuit board 100. Since many parts are the same as Example 1, only the characteristic parts will be explained. The shape of the wiring 105 in Example 2 is different from the shape of the wiring 105 in Example 1. Specifically, the width of one end of the wiring 105 connected to the first signal filter 110 is narrower than the width of the other end connected to one end of the capacitor 113 (the input terminal of the power supply circuit). In Example 2, the width of one end of the wiring 105 was set to 0.175 mm. The width of the other end of the wiring 105 was set to 0.35 mm. Everything else is the same as Example 1. The long dashed line E2 in Figure 3B shows the return loss characteristics in Example 2. The return loss at 6.25 GHz is -11.5 dB. According to Example 2, the return loss is smaller than that of the comparative example.

[0032] (Example 3) Figure 1D is a top view showing Example 3 of the circuit board 100. The shape of the wiring 104 in Example 3 is different from the shape of the wiring 104 in Example 1. Specifically, the width of one end of the wiring 104 connected to one end of the first signal filter 110 (the input terminal of the power supply circuit) is narrower than the width of the other end of the wiring 104 connected to the signal terminal 103a. In Example 3, the width of one end of the wiring 104 was set to 0.175 mm. The width of the other end of the wiring 104 was set to 0.35 mm. Everything else is the same as in Example 1. The short dashed line E3 in Figure 3B shows the return loss characteristics in Example 3. The return loss at 6.25 GHz is -12.0 dB. According to Example 3, the return loss is smaller than in the comparative example.

[0033] (Example 4) Figure 1E is a top view showing Embodiment 4 of the circuit board 100. The shapes of wiring 104 and wiring 105 in Embodiment 4 differ from those of wiring 104 and wiring 105 in Embodiment 1. Specifically, the width of one end of wiring 104 connected to one end of the first signal filter 110 (the input terminal of the power supply circuit) is narrower than the width of the other end of wiring 104 connected to the signal terminal 103a. In Embodiment 4, the width of one end of wiring 104 was 0.175 mm. The width of the other end of wiring 104 was 0.35 mm. In addition, the width of one end of wiring 105 connected to the first signal filter 110 is narrower than the width of the other end connected to one end of capacitor 113 (the input terminal of the power supply circuit). In Embodiment 4, the width of one end of wiring 105 was 0.175 mm. The width of the other end of wiring 105 was 0.35 mm. The lengths of wiring 104 and wiring 106 are the same as in Embodiment 1. The solid line E4 in Figure 3B shows the return loss characteristics in Example 4. The return loss at 6.25 GHz is -13.8 dB. According to Example 4, the return loss is smaller than that of the comparative example.

[0034] The relationship between the width of the wiring and the characteristic impedance of the wiring in the above-described Examples 1 to 4 will be described in detail based on Example 4. In the same wiring, the characteristic impedance of the narrower portion is higher than that of the wider portion. On the other hand, the lands (not shown) on which the first signal filter 110 is mounted to the board have a width that matches the dimensions of the component. Therefore, the width of the lands is often wider than the width of wiring 104 and wiring 105. In Examples 1 to 4, the width of the lands is 1.0 mm. As a result, the impedance at the lands becomes lower than the characteristic impedance of wiring 104 and wiring 105, causing an impedance mismatch between wiring 104 and wiring 105. In contrast, in Example 4, in order to compensate for the decrease in impedance at the lands, the width of one end of each of wiring 104 and wiring 105 that is connected to the lands is made narrower than the width of the other end that is connected to the first signal filter 110. As a result, the return loss in Example 4 is smaller than the return loss in Example 1.

[0035] (Example 5) Figure 1F is a top view showing Embodiment 5 of circuit board 100. Here, wire 105 branches off from wire 104 and is connected to one end of capacitor 113 (the first terminal of the signal circuit). The distance between the point where wire 105 branches off from wire 104 and the signal terminal 103a of wire 104 is 2.3 mm. The lengths of wires 104 and 106 are the same as in Embodiment 1.

[0036] The dashed line E5 in Figure 3B shows the return loss characteristics in Example 5. The return loss at 6.25 GHz is -6.7 dB. According to Example 5, the return loss is smaller than in the comparative example. A stub is generated when wiring 105 branches off from wiring 104, but if the stub is short, the reflection generated is small. In Example 5, the distance d2 between the point where wiring 105 branches off from wiring 104 and one end of the first signal filter 110 of wiring 104 is 1.2 mm. In the CXP standard, signals are transmitted at a maximum of 12.5 Gbps. When the transmission speed is 12.5 Gbps, the distance between the point where wiring 105 branches off from wiring 104 and the first signal filter 110 is preferably 2.0 mm or less.

[0037] [Second Embodiment] Figure 4 is a top view showing the circuit board 100 according to the second embodiment. The following description will focus on the differences between the second embodiment and the first embodiment.

[0038] In the second embodiment, the wiring 105 shown in the first embodiment is not provided. In the second embodiment, a wiring 120 (second wiring) is provided that connects the signal terminal 103a and the first terminal of the capacitor 113. Wirings 104 and 120 extend from the signal terminal 103a.

[0039] In the second embodiment, in a plan view of the printed circuit board 101, one terminal of the first signal filter 110 (the input terminal of the signal circuit) is located closer to the signal terminal 103a (main terminal) of the coaxial connector 103 than to the ground terminal 103b (sub-terminal). The first signal filter 110 is superimposed on the coaxial connector 103 in a plan view of the printed circuit board 101.

[0040] The length of wiring 104 corresponds to the distance d3 between signal terminal 103a and the first signal filter 110. The length of wiring 104 is shorter than the length of wiring 120. Furthermore, the length of wiring 104 is shorter than the distance d1 between signal terminal 103a and ground terminal 103b, and is preferably 0.7 times or less of the distance d1.

[0041] (Examples) Next, an embodiment of the circuit board 100 shown in Figure 4 will be described. Note that the configuration of the circuit board 100 in this embodiment is largely the same as the configuration of the circuit board 100 in the comparative example of the first embodiment shown in Figure 2. Therefore, the circuit board 100 shown in Figure 2 is used as a comparative example to this embodiment.

[0042] In this embodiment, the length of wire 104 is 0.5 mm. The length of wire 120 is 3 mm.

[0043] Furthermore, the dimensions of the first signal filter 110 in this embodiment are smaller than those of the comparative example. In this embodiment, the dimensions of the first signal filter 110 are 1.0 mm vertically and 0.5 mm horizontally in a plan view. On the other hand, the dimensions of the first signal filter 110 in the comparative example are 1.6 mm vertically and 0.8 mm horizontally. The dimensions of components other than the wiring 104 and the first signal filter 110 are the same as those of Embodiment 1 and the comparative example of the first embodiment. In this embodiment, since the dimensions of the first signal filter 110 are smaller than those of the comparative example, the possibility of a short circuit between the first signal filter 110 and the ground terminal 103b is also low. Therefore, the first signal filter 110 can be placed within the range enclosed by the four ground terminals 103b of the coaxial connector 103. In addition, by placing the first signal filter 110 closer to the signal terminal 103a, the wiring 104 that acts as a stub can be shortened.

[0044] Figure 5 shows the simulation results of the reflection characteristics of the circuit board 100 according to the second embodiment in an embodiment and a comparative example. The solid line E6 shows the return loss characteristics of this embodiment. The return loss at 6.25 GHz is -7.0 dB. This is smaller than the return loss shown in the comparative example in Figure 3A. In this embodiment, the length of the wiring 104 that forms the stub is preferably 2.5 mm or less when the transmission speed is 12.5 Gbps.

[0045] [Modified Embodiment] This disclosure is not limited to the embodiments described above and can be modified in various ways. For example, an example in which some components of one embodiment are added to another embodiment, or in which some components of another embodiment are replaced, is also an embodiment of this disclosure. Furthermore, the effects described in the embodiments are merely a list of the most preferred effects that result from this disclosure, and the effects of this disclosure are not limited to those described in the embodiments.

[0046] Furthermore, although the structure of the circuit board was described in the embodiments described above, the embodiments of this disclosure are not limited to circuit boards. An electronic device comprising a housing and a circuit board disposed inside the housing is also an embodiment of this disclosure. The electronic device may further include an imaging module disposed inside the housing that outputs the generated video signal to a signal transmission / reception circuit. The signal transmission / reception circuit outputs the video signal from the imaging module to an external device via a signal circuit and connector. Such an electronic device is also an embodiment of this disclosure. Examples of electronic devices include a CMOS camera that conforms to the CXP standard and transmits video signals, power, control signals, etc., via a single coaxial cable.

[0047] This disclosure includes the following components: (Composition 1) Wiring board and A connector having a main terminal and a sub-terminal is mounted on the aforementioned wiring board, A power supply circuit having input terminals and output terminals is mounted on the aforementioned wiring board, A signal circuit having a first terminal and a second terminal is mounted on the aforementioned wiring board, A signal transmitting and receiving circuit having power terminals and signal terminals is mounted on the aforementioned wiring board, A circuit board comprising, The main terminal and the sub-terminal penetrate the wiring board, The aforementioned wiring board includes a first wiring that connects the main terminal and the input terminal, A second wiring that connects the input terminal and the first terminal without going through the main terminal, A third wiring harness connecting the output terminal and the power terminal, It has a fourth wire connecting the second terminal and the signal terminal, The second wiring passes between the main terminal and the sub-terminal, A circuit board characterized by the following features. (Configuration 2) The connector further has a connection portion to which a coaxial cable is connected, The aforementioned sub-terminal is a ground terminal, The wiring board has a first mounting surface and a second mounting surface opposite to the first mounting surface. The signal circuit and the signal transmitting / receiving circuit are mounted on the first mounting surface. The first terminal and the second terminal are soldered to the first mounting surface. The connected portion is located on the second mounting surface side, The second wiring is provided on the first mounting surface. The circuit board according to configuration 1, characterized by the above. (Composition 3) In the first wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the main terminal. The circuit board according to configuration 1, characterized by the above. (Composition 4) In the second wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the first terminal. The circuit board according to configuration 1, characterized by the above. (Composition 5) The connector further has other sub-terminals, The second wiring does not pass between the other sub-terminal and the main terminal. The circuit board according to configuration 1, characterized by the above. (Composition 6) The second wiring branches off from the first wiring and is connected to the first terminal. The circuit board according to configuration 1, characterized by the above. (Composition 7) The second wiring branches off from the first wiring at a position closer to the input terminal than the main terminal. The circuit board according to configuration 6, characterized by the features described above. (Composition 8) The aforementioned power supply circuit is A first signal filter connected to the first wiring and having a first cutoff frequency, A second signal filter connected to the first signal filter and having a second cutoff frequency lower than the first cutoff frequency, A converter connected to the second signal filter and outputting a power supply voltage to the power supply terminal of the signal transmission and reception circuit, including, The circuit board according to configuration 1, characterized by the above. (Composition 9) The aforementioned signal circuit is A capacitor connected to the first wiring, The capacitor and the resistor connected to the signal terminal of the signal transmitting and receiving circuit, including, The circuit board according to feature 1. (Composition 10) The sum of the input impedance of the signal transmitting / receiving circuit and the resistance value of the resistor matches the characteristic impedance of the third wiring. The circuit board according to configuration 9, characterized by the features described therein. (Composition 11) In a plan view of the aforementioned wiring board, the distance between the main terminal and the input terminal is longer than the distance between the main terminal and the sub-terminal. The circuit board according to configuration 1, characterized by the above. (Composition 12) The length of the first wire is shorter than the length of the second wire. The circuit board according to configuration 1, characterized by the above. (Composition 13) Wiring board and A connector having a main terminal and a sub-terminal is mounted on the aforementioned wiring board, A power supply circuit having input terminals and output terminals is mounted on the aforementioned wiring board, A signal circuit having a first terminal and a second terminal is mounted on the aforementioned wiring board, A circuit board comprising a signal transmitting and receiving circuit having power terminals and signal terminals, mounted on the aforementioned wiring board, The main terminal and the sub-terminal penetrate the wiring board. The aforementioned wiring board includes a first wiring that connects the main terminal and the input terminal, A second wiring harness connecting the main terminal and the first terminal, A third wiring harness connecting the output terminal and the power terminal, It has a fourth wire connecting the second terminal and the signal terminal, In a plan view of the aforementioned wiring board, the input terminal is positioned closer to the main terminal than the sub-terminal. A circuit board characterized by the following features. (Composition 14) The length of the first wiring is 0.7 times or less the distance between the main terminal and the sub-terminal. The circuit board according to configuration 13, characterized by the features described above. (Composition 15) The length of the first wire is shorter than the length of the second wire. The circuit board according to configuration 13, characterized by the features described above. (Composition 16) The connector further has a connection portion to which a coaxial cable is connected, The aforementioned sub-terminal is a ground terminal, The wiring board has a first mounting surface and a second mounting surface opposite to the first mounting surface. The signal circuit and the signal transmitting / receiving circuit are mounted on the first mounting surface. The first terminal and the second terminal are soldered to the first mounting surface. The connected portion is located on the second mounting surface side, The second wiring is provided on the first mounting surface. The circuit board according to configuration 13, characterized by the features described above. (Composition 17) The aforementioned power supply circuit is A first signal filter connected to the first wiring and having a first cutoff frequency, A second signal filter connected to the first signal filter and having a second cutoff frequency lower than the first cutoff frequency, A converter connected to the second signal filter and outputting a power supply voltage to the power supply terminal of the signal transmission and reception circuit, Includes, The first signal filter is superimposed on the connector in a plan view of the wiring board. The circuit board according to configuration 13, characterized by the features described above. (Composition 18) In the first wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the main terminal. The circuit board according to configuration 13, characterized by the features described above. (Composition 19) The casing and A circuit board according to any one of configurations 1 to 18, arranged inside the aforementioned housing, An electronic device characterized by having the following features. (Composition 20) The housing further comprises an imaging module, which is located inside the housing and outputs the generated video signal to the signal transmission / reception circuit. The signal transmission and reception circuit outputs the video signal to an external device via the signal circuit and the connector. The electronic device according to configuration 19, characterized by the features described above. [Explanation of symbols]

[0048] 100 circuit board 101 Printed circuit board 102 Signal Transceiver Circuit 103 Coaxial Connector 103a signal terminal 103b Ground terminal Wiring 104, 105, 106, 107, 108 110 First signal filter 111 Second signal filter 112 DC-DC Converters 113 Capacitor 114 resistors

Claims

1. Wiring board and A connector having a main terminal and a sub-terminal is mounted on the aforementioned wiring board, A power supply circuit having input terminals and output terminals is mounted on the aforementioned wiring board, A signal circuit having a first terminal and a second terminal is mounted on the aforementioned wiring board, A signal transmitting and receiving circuit having power terminals and signal terminals is mounted on the aforementioned wiring board, A circuit board comprising, The main terminal and the sub-terminal penetrate the wiring board, The aforementioned wiring board includes a first wiring that connects the main terminal and the input terminal, A second wiring that connects the input terminal and the first terminal without going through the main terminal, A third wiring harness connecting the output terminal and the power terminal, It has a fourth wire connecting the second terminal and the signal terminal, The second wiring passes between the main terminal and the sub-terminal, A circuit board characterized by the following features.

2. The connector further has a connection portion to which a coaxial cable is connected, The aforementioned sub-terminal is a ground terminal, The wiring board has a first mounting surface and a second mounting surface opposite to the first mounting surface. The signal circuit and the signal transmission / reception circuit are mounted on the first mounting surface. The first terminal and the second terminal are soldered to the first mounting surface. The connected portion is located on the second mounting surface side, The second wiring is provided on the first mounting surface. The circuit board according to claim 1.

3. In the first wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the main terminal. The circuit board according to claim 1.

4. In the second wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the first terminal. The circuit board according to claim 1.

5. The connector further has other sub-terminals, The second wiring does not pass between the other sub-terminal and the main terminal. The circuit board according to claim 1.

6. The second wiring branches off from the first wiring and is connected to the first terminal. The circuit board according to claim 1.

7. The second wiring branches off from the first wiring at a position closer to the input terminal than the main terminal. The circuit board described in proc.

6.

8. The aforementioned power supply circuit is A first signal filter having a first cutoff frequency is connected to the first wiring, A second signal filter connected to the first signal filter and having a second cutoff frequency lower than the first cutoff frequency, A converter connected to the second signal filter and outputting a power supply voltage to the power supply terminal of the signal transmission and reception circuit, including, The circuit board according to claim 1.

9. The aforementioned signal circuit is A capacitor connected to the first wiring, The capacitor and the resistor connected to the signal terminal of the signal transmitting and receiving circuit, including, The circuit board according to claim 1.

10. The sum of the input impedance of the signal transmitting and receiving circuit and the resistance value of the resistor matches the characteristic impedance of the third wiring. The circuit board according to feature 9.

11. In a plan view of the aforementioned wiring board, the distance between the main terminal and the input terminal is longer than the distance between the main terminal and the sub-terminal. The circuit board according to claim 1.

12. The length of the first wire is shorter than the length of the second wire. The circuit board according to claim 1.

13. Wiring board and A connector having a main terminal and a sub-terminal is mounted on the aforementioned wiring board, A power supply circuit having input terminals and output terminals is mounted on the aforementioned wiring board, A signal circuit having a first terminal and a second terminal is mounted on the aforementioned wiring board, A circuit board comprising a signal transmitting and receiving circuit having power terminals and signal terminals, mounted on the aforementioned wiring board, The main terminal and the sub-terminal penetrate the wiring board. The aforementioned wiring board includes a first wiring that connects the main terminal and the input terminal, A second wiring that connects the main terminal and the first terminal, A third wiring harness connecting the output terminal and the power terminal, It has a fourth wire connecting the second terminal and the signal terminal, In a plan view of the aforementioned wiring board, the input terminal is positioned closer to the main terminal than the sub-terminal. A circuit board characterized by the following features.

14. The length of the first wiring is 0.7 times or less the distance between the main terminal and the sub-terminal. The circuit board according to claim 13, characterized in that it is a circuit board.

15. The length of the first wire is shorter than the length of the second wire. The circuit board according to claim 13, characterized in that it is a circuit board.

16. The connector further has a connection portion to which a coaxial cable is connected, The aforementioned sub-terminal is a ground terminal, The wiring board has a first mounting surface and a second mounting surface opposite to the first mounting surface. The signal circuit and the signal transmission / reception circuit are mounted on the first mounting surface. The first terminal and the second terminal are soldered to the first mounting surface. The connected portion is located on the second mounting surface side, The second wiring is provided on the first mounting surface. The circuit board according to claim 13, characterized in that it is a circuit board.

17. The aforementioned power supply circuit is A first signal filter having a first cutoff frequency is connected to the first wiring, A second signal filter connected to the first signal filter and having a second cutoff frequency lower than the first cutoff frequency, A converter connected to the second signal filter and outputting a power supply voltage to the power supply terminal of the signal transmission and reception circuit, Includes, The first signal filter is superimposed on the connector in a plan view of the wiring board. The circuit board according to claim 13, characterized in that it is a circuit board.

18. In the first wiring, the width of one end connected to the input terminal is narrower than the width of the other end connected to the main terminal. The circuit board according to claim 13, characterized in that it is a circuit board.

19. The casing and A circuit board according to any one of claims 1 to 18, disposed inside the housing, An electronic device characterized by having the following features.

20. The housing further comprises an imaging module, which is located inside the housing and outputs the generated video signal to the signal transmission / reception circuit. The signal transmission and reception circuit outputs the video signal to an external device via the signal circuit and the connector. The electronic device according to feature 19.

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