JP5193104B2 - Printed circuit board module - Google Patents

Description

  The present invention relates to a printed circuit board module.

  There is a printed circuit board module having an inter-board connector for connecting a pair of printed circuit boards and exchanging electrical signals between these printed circuit boards. 12-14 is a figure explaining the conventional printed circuit board module 100. FIG. 12 is a cross-sectional view of the printed circuit board module 100, FIG. 13 is a cross-sectional view of FIG. 12 viewed from the direction of arrow X, and FIG. 14 is a front view of FIG. 13 viewed from the direction of arrow Y. is there. As shown in these drawings, the printed circuit board module 100 is configured by connecting two printed circuit boards 110 and 120 by an inter-board connector 140. The printed circuit board 110 includes an insulating layer 111, a ground layer 112, and a signal transmission layer 115 having signal transmission lines 115a to 115c. The printed circuit board 120 includes an insulating layer 121, a ground layer 122, and a signal transmission layer 125 having signal transmission lines 125a to 125c. The ground layer 112 of the printed circuit board 110 and the ground layer 122 of the printed circuit board 120 are connected to each other by a conductor 130 as shown in FIG. In addition, the signal transmission layer 115 and the signal transmission layer 125 are connected to each other by a board-to-board connector 140. Specifically, as shown in FIGS. 12 and 13, the signal transmission line 115a and the signal transmission line 125a are connected by a conductor 135a, the signal transmission line 115b and the signal transmission line 125b are connected by a conductor 135b, and the signal transmission line 115c and the signal transmission line 125c are connected by a conductor 135c. The conductors 135a, 135b, and 135c are covered with a covering 136 such as a resin.

  In FIG. 13, the signals are transmitted from the left to the right through the signal transmission lines 125 a to 125 c of the lower printed circuit board 120 as indicated by arrows, and the upper printed circuit board 110 is connected via the inter-board connector 140. The signal transmission lines 115a to 115c are transmitted from the right to the left. As shown in FIG. 14, the signal transmission lines 125a to 125c provided on the printed circuit board 120 have microstrip lines and the like arranged at a predetermined interval.

  By the way, due to the narrow pitch between the terminals (conductors) of the board-to-board connector 140 and the high frequency of the signal to be transmitted, the signal transmission line 125a and the signal transmission are caused by the coupling between the lines as shown by arrows in FIG. Coupling occurs between the lines 125b and between the signal transmission line 125b and the signal transmission line 125c, which causes deterioration of transmission characteristics. In particular, such coupling is likely to occur near a terminal where impedance mismatch occurs. That is, a cheaper connector does not consider high-frequency applications, and in particular, impedance is often not considered, which is a problem. The influence of such coupling becomes significant when a load impedance deviating from the characteristic impedance of the transmission line is connected to the line.

  For example, assuming that the characteristic impedance of the signal transmission line is designed to be 50Ω, consider the influence between the signal transmission lines 125a and 125b on the substrate as shown in FIG. The signal transmission line 125a is used as a signal line with an impedance of 50Ω, and a high impedance component such as a power source is connected to the signal transmission line 125b. When a signal is input to the left end of the signal transmission line 125a, signals are exchanged across the line as indicated by an arrow S1 in a frequency band in which coupling between lines occurs (a band where isolation is not good). The signal that has passed through the signal transmission line 125b is reflected by the influence of the high-impedance component, and a component that returns as indicated by the arrow S2 is generated. Similarly, due to the coupling between the lines, a component returning to the signal transmission line 125a is generated as indicated by an arrow S3. In this way, the component returned to the original causes deterioration of the signal quality, and becomes a frequency characteristic having an abrupt transmission loss when viewed from a passing characteristic of the signal transmission line. FIG. 16A shows transmission characteristics corresponding to the case where there is no adjacent signal transmission line. On the other hand, FIG. 16B shows a case where another signal transmission line is placed close to the target signal transmission line and the other signal transmission line is open (total reflection), as in FIG. The transmission characteristics are shown. From these comparisons, in the case of FIG. 16B where line-to-line coupling occurs, a transmission loss occurs in the vicinity of 4 GHz. This loss tends to occur when the isolation between the lines is poor, and the frequency changes depending on the distance between the inter-board connector and the high impedance component.

  Therefore, in order to prevent such transmission loss, as shown in Patent Document 1, a connector provided with ferrite has been proposed. Patent Document 2 proposes a technology for solving such a problem by providing a transmission line having a pseudo coaxial structure by providing a terminal for signal transmission and a terminal for grounding. Furthermore, Patent Document 3 proposes a technique for reducing unnecessary radiation by enclosing a capacitor in a connector in advance.

JP 2006-099971 A JP 09-330770 A Japanese Patent Laid-Open No. 09-2332014

  By the way, in the technique disclosed in Patent Document 1, it is necessary to select a material in consideration of aging degradation of ferrite and high-frequency characteristics, and there is a problem in that the reliability of the module is reduced and the cost is increased. Further, the technique disclosed in Patent Document 2 has a problem that the size of the connector is increased by the provision of a grounding terminal, and it is difficult to reduce the size of the module. Furthermore, in the technique disclosed in Patent Document 3, there is a case in which characteristic deterioration cannot be suppressed by using only a capacitor, and there is a problem that the connector becomes complicated due to the included structure, leading to an increase in cost. Furthermore, when the capacitance value of the capacitor is large, although there is an effect in reducing crosstalk, the impedance of the signal transmission line into which the capacitor is inserted is lowered, so that there is a problem that it is difficult to cope with high frequency. More specifically, in the technique disclosed in Patent Document 3, in the case of FIG. 15, the capacitor 150 is connected to the signal transmission line 125b as shown in FIG. When the capacitor 150 is connected, the characteristics of the signal transmission line 125a are improved as shown in FIG. 18A (the transmission loss near 4 GHz shown in FIG. 16 is improved). On the other hand, the signal transmission line 125b has a problem that the band of the pass characteristic becomes narrow as shown in FIG.

  Therefore, the present invention is to provide a printed circuit board module with less quality degradation of a signal to be transmitted.

In order to solve the above problems, a printed circuit board module according to the present invention includes at least two printed circuit boards each having a signal transmission conductor and a ground conductor, and a plurality of signal transmission lines included in the signal transmission conductor. In a printed circuit board module having an inter-board connector connected between printed circuit boards and a conductor connecting the ground conductors between printed circuit boards, the signal transmission line is connected to the side where the inter-board connector is not connected. When there is a signal transmission line to which a circuit element that does not match the characteristic impedance of the transmission line is added, one end of the capacitive and inductive circuit elements connected in series is connected to a part of the signal transmission line, Connect the other end to the ground conductor of the printed circuit board on which the signal transmission line is formed, and connect the capacitive and induction connected in series Resonant frequency of the circuit elements is set so as to ensure the necessary passband of the signal transmitted through the signal transmission line, characterized in that.
According to this configuration, it is possible to provide a printed circuit board module in which the quality of transmitted signals is small.

According to another invention, in addition to the above invention, one end of the series-connected capacitive and inductive circuit elements is connected in the vicinity of a connection point between the signal transmission line and the inter-board connector. It is characterized by.
According to this configuration, by connecting the capacitive and inductive circuit elements connected in series in the vicinity of the board-to-board connector where impedance mismatch is likely to occur, it is possible to effectively prevent quality degradation of the transmitted signal. Can do.

In addition to the above-mentioned invention, another invention is configured such that a composite transmission line is configured by connecting the signal transmission line and the inter-board connector, and the capacitive and inductive circuit elements connected in series are connected to the composite circuit. The resonance frequency is set to a frequency higher than the frequency band in which the isolation between the transmission lines is smaller than approximately 30 dB.
According to this configuration, it is possible to prevent narrowing of the passage characteristics of the transmission line to which the capacitive and inductive circuit elements connected in series are connected while preventing the isolation between the transmission lines from being lowered.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the printed circuit board module with little quality degradation of the signal to transmit.

It is sectional drawing which shows the structural example of the printed circuit board module which concerns on this invention. It is sectional drawing at the time of seeing FIG. 1 from the direction of arrow X. FIG. 3 is a surface view when FIG. 2 is viewed from the direction of an arrow Y. It is a figure which shows the passage characteristic and isolation characteristic in the case of only a signal transmission line in case two transmission paths are matched. FIG. 5A shows the characteristics of the present embodiment, and FIG. 5B shows the characteristics of the conventional example. It is an application example of the printed circuit board module according to the present invention. It is a figure which shows other embodiment of this invention. It is the example of arrangement | positioning of the series circuit in this invention. It is another example of arrangement | positioning of the series circuit in this invention. It is another example of arrangement | positioning of the series circuit in this invention. It is another example of arrangement | positioning of the series circuit in this invention. It is a figure which shows the structure of the conventional printed circuit board module. It is sectional drawing which looked at FIG. 12 from the direction of arrow X. It is the surface view which looked at FIG. 12 from the direction of arrow Y. It is a figure explaining the signal transmitted between adjacent signal transmission lines. FIG. 16A shows the pass characteristic when there is no adjacent signal transmission line, and FIG. 16B shows the pass characteristic when there is an adjacent signal transmission line. This is a conventional method for improving isolation characteristics. FIG. 18A shows the pass characteristic of the signal transmission line 125a, and FIG. 18B shows the pass characteristic of the signal transmission line 125b.

  Next, an embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view showing a configuration example of a printed circuit board module 1 according to an embodiment of the present invention. 1 to 3 correspond to FIGS. 12 to 14, but in the present embodiment shown in FIGS. 1 to 3, in order to simplify the description, the case where there are two signal transmission lines is used. An example is given. Of course, there may be three or more signal transmission lines. As shown in FIG. 1, the printed circuit board module 1 is configured by connecting two printed circuit boards 10 and 20 by an inter-board connector 40. The printed circuit board 10 includes an insulating layer 11, a ground layer 12 (corresponding to “ground conductor” in the claims), and a signal transmission layer 15 (“signal transmission conductor” in the claims) including signal transmission lines 15a and 15b. Correspondence). The printed circuit board 20 includes an insulating layer 21, a ground layer 22, and a signal transmission layer 25 including signal transmission lines 25a and 25b.

  In this example, the ground layer 12 of the printed circuit board 10 and the ground layer 22 of the printed circuit board 20 are connected to each other by two conductors 30. The signal transmission layer 15 and the signal transmission layer 25 are connected to each other by the inter-board connector 40. Specifically, as shown in FIGS. 1 and 2, the signal transmission line 15a and the signal transmission line 25a are connected by a conductor 35a, and the signal transmission line 15b and the signal transmission line 25b are connected by a conductor 35b. The conductors 35a and 35b are covered with a covering 36 such as a resin.

  FIG. 2 is a cross-sectional view when viewed from the direction of arrow X in FIG. As shown in FIG. 2, the signal transmission lines 15a and 15b and the signal transmission lines 25a and 25b are arranged so as to extend from the left end of the printed circuit boards 10 and 20 toward the right side in the figure, and the inter-board connector 40 is The signal transmission lines 15a and 25b are disposed near the right ends of the signal transmission lines 25a and 25b and connect the signal transmission layers 15 and 25 of the upper and lower printed circuit boards 10 and 20 to each other. Further, the signal to be transmitted is transmitted from the left to the right of the signal transmission lines 25a and 25b of the lower printed circuit board 20, as indicated by an arrow in the figure, and passes through the board-to-board connector 40 to the upper side. The signal is transmitted from the right to the left of the signal transmission lines 15a and 15b of the printed circuit board 10.

  FIG. 3 is a view showing the upper surface of the printed circuit board 20 when viewed from the direction of the arrow Y in FIG. As shown in FIG. 3, the signal transmission lines 25a and 25b provided on the printed circuit board 20 have rectangular lines arranged at predetermined intervals. In the example of this figure, the signal transmission line 25a has a characteristic impedance of 50Ω, and a circuit element that is matched up to a high frequency is connected to a part thereof. On the other hand, the signal transmission line 25b is not matched with the characteristic impedance, for example, a high impedance element is connected to a part thereof. In addition, one terminal of a capacitor 51 (capacitive circuit element) is connected in the vicinity of a portion where the signal transmission line 25b and the conductor 35b of the inter-board connector 40 are connected, and the other terminal of the capacitor 51 is connected. Is connected to one terminal of a coil 52 (inductive circuit element). The other terminal of the coil 52 is connected (grounded) to the ground layer 22 of the printed circuit board 20. That is, one end of a series circuit 50 in which a capacitor 51 and a coil 52 are connected in series is connected near the portion where the signal transmission line 25b and the conductor 35b of the inter-board connector 40 are connected, and the other end of the circuit is connected Connected (grounded) to the ground layer 22. In addition, the capacitor | condenser 51 and the coil 52 can be comprised by chip components, for example. 3 shows only the printed circuit board 20 side, a similar series circuit 60 (see FIG. 8) is also provided on the printed circuit board 10 side as necessary. That is, as viewed from the board-to-board connector 40, a series circuit is provided for a transmission line in which impedance mismatch occurs.

  Next, the operation of this embodiment will be described.

  4 shows a state in which the capacitor 51, the coil 52, and the high-impedance element are not connected in the printed circuit board module 1 shown in FIG. 1 (only the printed circuit boards 10 and 20 are connected by the inter-board connector 40). It is a figure which shows the passage characteristic and isolation characteristic of signal transmission line 25a, 25b in FIG. More specifically, in FIG. 4, a curve connecting a plurality of triangles indicates the pass characteristics of the signal transmission lines 25a and 25b. Since the signal transmission lines 25a and 25b are both in a matched state, they have the same characteristics. A curve connecting a plurality of rhombuses indicates the mutual isolation characteristics of the signal transmission lines 25a and 25b.

  In this embodiment, the resonance frequency of the capacitor 51 and the coil 52 is set to a frequency higher than 1 GHz, which is a frequency band in which isolation is smaller than 30 dB. Generally, the resonance frequency of a resonance circuit composed of L and C is defined by 1 / (2π × √ (L × C)). Therefore, for example, when the resonance frequency is set in the vicinity of 2 GHz larger than 1 GHz, L = 2.2 nH and C = 3.3 pF may be set (more precisely, the resonance frequency is about 1.87 GHz). It should be noted that when actually setting the resonance frequency, it is necessary to expand to which band the pass characteristic of the signal transmission line 25b needs to be widened, and the tolerance of ripples of the transmission characteristic generated by giving the resonance characteristic. Set in consideration. That is, the resonance frequency is set to a frequency that can secure a necessary pass band of signals transmitted through the signal transmission lines 15b and 25b.

  5A, the capacitor 51 and the coil 52 having the element values described above are connected to the printed circuit board module 1 shown in FIG. 1, and the signal transmission line 25a is in a state in which impedance matching is achieved. The line 25b shows characteristics when a high impedance element is connected. In this figure, a curve connecting a plurality of rhombuses indicates the isolation characteristics of the signal transmission lines 25a and 25b. As shown in this figure, the isolation characteristic has a minimum point in the vicinity of 2 GHz which is the resonance frequency. A curve connecting a plurality of triangles indicates the pass characteristic of the signal transmission line 25b, and a curve connecting a plurality of circles indicates the pass characteristic of the signal transmission line 25a. FIG. 5B shows characteristics of the conventional printed circuit board module 100 shown in FIG. In FIG. 5B, a curve connecting a plurality of rhombuses indicates the isolation characteristics of the signal transmission lines 125a and 125b, and a curve connecting a plurality of triangles indicates the pass characteristics of the signal transmission lines 125b. A curve connecting a plurality of circles indicates the pass characteristic of the signal transmission line 125a. From the comparison between FIGS. 5A and 5B, in the printed circuit board module 1 of the present embodiment, the cut-off frequency fc (frequency at which 3 dB is attenuated) of the signal transmission line 25b is higher than in the conventional case. ing. Specifically, in the conventional example, the cutoff frequency fc exists near 500 MHz, but in the example of the present embodiment, the cutoff frequency fc exists near 750 MHz. That is, the frequency band is expanded to about 1.5 times. In FIG. 5A, since a series resonant circuit is used and the impedance is drastically reduced near the resonance frequency, the cutoff characteristic of the signal transmission line 25b is steep compared to FIG. 5B. Yes.

  Note that the transmission characteristics of the signal transmission line 25a are not changed from those of the signal transmission line 125a. That is, as shown in FIG. 5A, the transmission characteristic of the signal transmission line 25b attenuates the signal with a cut-off frequency around 750 MHz, so that the signal that returns to the signal transmission line 25a (see FIG. 15). As a result, transmission loss as shown in FIG. 16B can be prevented.

  FIG. 6 is a diagram illustrating an application example of the printed circuit board module 1 of the present embodiment. In the example of this figure, a signal processing unit having a signal generation unit 71, an amplification circuit 72, and a power source control signal generation unit 73 is disposed on the printed circuit board 20, and a mixer circuit 74, a low-pass filter is disposed on the printed circuit board 10. 75, an amplifying circuit 76, and a high frequency circuit section having a band pass filter 77 are arranged. The printed circuit boards 10 and 20 are connected by an inter-board connector 40. Further, the output of the bandpass filter 77 is connected to the antenna unit 80. In the circuit of FIG. 6, it is necessary to send a control signal for switching on / off the amplifier circuit 76 present in the high-frequency circuit section from the power control signal generation section 73 present in the signal processing section. Although it is a power supply line, it is necessary to cope with a relatively high frequency.

  Here, with respect to the signal transmission line on the conductor 35a side, since a high-frequency signal is transmitted, both the amplifier circuit 72 and the mixer circuit 74 are set to a frequency having high impedance matching. However, the signal transmission line on the conductor 35b side is connected to the control signal generation unit 73 of the power source and the low-pass filter 75, and these are not matched in impedance. For this reason, in the example of FIG. 6, on the printed circuit board 20 side, one end of a series circuit including a capacitor and a coil similar to FIG. 3 is connected in the vicinity of the connection portion between the conductor 35b and the signal transmission line 25b. Connected to the ground layer 22. On the other hand, on the printed circuit board 10 side, one end of a series circuit including a capacitor and a coil similar to that in FIG. 3 is connected in the vicinity of the connection portion between the conductor 35b and the signal transmission line 15b, and the other end is connected to the ground layer 12. Yes. According to such a configuration, the signal transmission lines 15b and 25b on the conductor 35b side do not deteriorate the passing characteristics of the signal transmission lines 15a and 25a on the conductor 35a side. 76, a control signal for switching on and off.

  As described above, according to the embodiment of the present invention, when there is a signal transmission line to which a circuit element that does not match the characteristic impedance of the signal transmission line is present, a part of the signal transmission line is connected in series. Connect one end of the connected capacitive and inductive circuit elements, connect the other end to the ground layer of the printed circuit board on which the signal transmission line is formed, and connect the capacitive and inductive circuit elements connected in series. Since the resonance frequency is set to a frequency that can secure the necessary pass band of the signal transmitted through the signal transmission line, it does not affect the pass characteristics of other adjacent signal transmission lines and The pass characteristic can be improved.

  In addition, in this way, by connecting capacitive and inductive circuit elements connected in series in the vicinity of the board-to-board connector, an inexpensive board-to-board connector that is not created in consideration of impedance is used Even so, it is possible to prevent the transmission characteristics from deteriorating.

  In addition, said embodiment is an example and various deformation | transformation aspects exist besides this. For example, the relationship between the capacitor 51 and the coil 52 shown in FIG. 3 may be reversed. That is, the coil 52 may be connected to the inter-board connector 40 side, and the capacitor 51 may be connected to the ground layer 22 side.

  Further, instead of using capacitors and coils as chip components, for example, as shown in FIG. 7, a C component and an L component configured by a microstrip line may be used. Specifically, in the example of FIG. 7, the C component is generated by the wiring pattern 91 and the right end portion of the signal transmission line 25 b, and the L component is generated by the wiring pattern 92. Further, the connection to the ground layer 22 can be made through the through hole 93 or the like. By using such a microstrip line 90, a circuit can be formed at a lower cost than when a chip component is used.

  Further, in the above embodiment, as shown in the schematic configuration in FIG. 8, the signal transmission layers 15 and 25 are arranged at opposing positions of the printed boards 10 and 20 (substantially the same position in the left-right direction in the figure) and in series. The circuits 50 and 60 are connected to the end portions of the signal transmission lines 15b and 25b on the board-to-board connector 40 side by wirings 53 and 63, and are connected to the ground layers 12 and 22 by through-hole wirings 54 and 64. For example, it is good also as a structure as shown in FIG. In the printed circuit board module 1A shown in FIG. 9, the signal transmission layer 15 is disposed so as to extend from the left end of the printed circuit board 10 toward the right side, and the signal transmission layer 25 is disposed so as to extend from the right end of the printed circuit board 20 toward the left side. Has been. The series circuits 50 and 60 are connected to ends of the signal transmission lines 15b and 25b on the board-to-board connector 40 side by wirings 53 and 63, respectively. The series circuits 50 and 60 are connected to the ground layers 12 and 22 by through-hole wirings 54 and 64. Further, the signal is input to the right end of the signal transmission line 25b of the printed circuit board 20 and transmitted to the left, transmitted to the printed circuit board 10 through the inter-board connector 40, and transmitted to the left side through the signal transmission line 15b. Is done. The same effect can be obtained even with the printed circuit board module 1A having such a configuration.

  Further, as shown in FIG. 8, the series circuits 50 and 60 are not connected to the end portions of the signal transmission lines 15b and 25b on the board-to-board connector 40 side, but as shown in FIG. You may make it connect to a part. In the example of the printed circuit board module 1B shown in FIG. 10, a series circuit 50 is provided in an empty portion of the signal transmission layer 25, and the series circuit 50 is connected to a part of the signal transmission line 25b. The series circuit 50 is connected to the ground layer 12 by the wiring 54 a and the wiring 54 disposed in the through hole. In FIG. 10, only the printed circuit board 20 is shown, but the printed circuit board 10 has the same configuration. A similar effect can be obtained by such a configuration.

  Further, as shown in FIG. 8, the series circuits 50 and 60 may be provided on the ground layers 12 and 22 side as shown in FIG. 11 instead of being provided on the signal transmission layers 15 and 25 side. In the example of the printed circuit board module 1 </ b> C shown in FIG. 11, the series circuits 50 and 60 are provided on the ground layers 12 and 22 side, and these series circuits 50 and 60 penetrate the wirings 53 and 63 and the insulating layers 11 and 21. They are connected to each other by wirings 55 and 65 embedded in the through holes. In addition, the area | region where the series circuits 50 and 60 of the ground layers 12 and 22 are arrange | positioned excludes a conductor, and the series circuits 50 and 60 are arrange | positioned in the said excluded area | region. A similar effect can be obtained by such a configuration.

  In addition, it does not select and apply any one of the configurations of FIG. 8 to FIG. 11 described above. For example, according to the layout of signal transmission lines and circuit elements in the printed boards 10 and 20, The optimum arrangement may be selected from FIGS. 8 to 11 and applied. For example, a method of connecting the series circuit 50 to the printed circuit board 20 by the method of FIG. 8 and connecting the series circuit 60 to the printed circuit board 10 by the method of FIG. In addition, only one series circuit element may be provided for each printed circuit board as a target, but a plurality of series circuit elements may be provided by a combination of the configurations shown in FIGS.

  In the above embodiment, only two signal transmission lines are provided, but three or more signal transmission lines may be provided. Further, the case of two printed boards has been described as an example, but three or more printed boards may be used.

  In the above embodiment, the signal transmission layer includes only the signal transmission line. However, the signal transmission layer may include a ground line. In the present embodiment, the “signal transmission layer” means a layer in which signals are mainly transmitted. The same applies to the ground layer, and the ground layer may include a signal transmission line.

  The conductor connecting the ground layers is an example constituted by a conductor different from the inter-board connector in each of the above embodiments, but the inter-board connector may have a function of connecting the ground layers to each other. Further, the inter-board connector and another conductor may be used in combination.

DESCRIPTION OF SYMBOLS 1 Printed circuit board module 10,20 Printed circuit board 11,21 Insulating layer 12,22 Grounding layer (grounding conductor)
15 Signal transmission layer (signal transmission conductor)
15a, 15b Signal transmission line 25 Signal transmission layer (signal transmission conductor)
25a, 25b Signal transmission line 30 Conductor 35a, 35b Conductor 36 Covering body 40 Inter-board connector 51 Capacitor (capacitive circuit element)
52 Coils (inductive circuit elements)

Claims (3)

At least two printed circuit boards each having a signal transmission conductor and a ground conductor, an inter-board connector for connecting a plurality of signal transmission lines included in each of the signal transmission conductors between the printed circuit boards, and the ground conductors In a printed circuit board module having a conductor connecting between the printed circuit boards,
If there is a signal transmission line to which a circuit element that does not match the characteristic impedance of the signal transmission line is present on the side where the inter-board connector of the signal transmission line is not connected, a part of the signal transmission line Connect one end of the capacitive and inductive circuit elements connected in series, connect the other end to the ground conductor of the printed circuit board on which the signal transmission line is formed, and connect the capacitive and inductive in series The resonance frequency of the circuit element is set so as to ensure the necessary passband of the signal transmitted through the signal transmission line,
A printed circuit board module.   The printed circuit board module according to claim 1, wherein one end of the capacitive and inductive circuit elements connected in series is connected in the vicinity of a connection point between the signal transmission line and the inter-board connector. The signal transmission line and the inter-board connector are connected to form a composite transmission line, and the capacitive and inductive circuit elements connected in series have a frequency at which the isolation between the composite transmission lines is less than about 30 dB. The printed circuit board module according to claim 1, wherein the resonance frequency is set to a frequency higher than the band.

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