JPWO2014045792A1 - Circuit board and electronic equipment - Google Patents

Abstract

The circuit board (10) has two or more wiring layers (for example, a first wiring layer (11) and a second wiring layer (12)). In these two or more wiring layers, there are a signal wiring (13), a ground wiring (14) arranged in parallel to the signal wiring (13), and a resonance line (linear conductor) (16). Is formed. The signal wiring (13) is arranged in the first wiring layer (11). The resonance line (16) is arranged on the second wiring layer (12) so that at least a part of the resonance line (16) and a part of the signal wiring (13) overlap each other. The resonance line (16) is connected to the ground wiring (14), and at least one end (161) of the resonance line (16) is an open end.

Description

  The present invention relates to a circuit board and an electronic device.

  A circuit board having a transmission line is mounted on various electronic devices.

  Patent Documents 1, 2, and 3 describe circuit boards having transmission lines, respectively. Among these, Patent Documents 1 and 2 describe a circuit board having a coplanar transmission line.

  In an electronic device in which a large number of semiconductor elements such as integrated circuits are mounted on a circuit board, there is a problem in that electromagnetic noise (electromagnetic waves) generated from each component affects other components and causes malfunction. One of such events is a phenomenon in which noise is superimposed on the signal wiring.

  As a technique for suppressing the noise from being superimposed on the signal wiring, there is a technique of inserting a filter (low-pass filter) constituted by a capacitor, an inductor or the like into the signal wiring.

Japanese Patent Laid-Open No. 11-54943 JP 2004-140608 A JP 2009-252816 A

  However, the method of inserting a filter (low-pass filter) composed of components such as a capacitor and an inductor into the signal wiring requires an area for mounting the components on the circuit board, which leads to an increase in the size of the circuit board.

  Further, in addition to the cost of the components, the management costs of the components, the work man-hours and lead times for mounting the components increase. Furthermore, since it is necessary to assign a filter to each signal wiring, the design man-hour increases. Depending on the device, dozens to hundreds of capacitors and inductors may be mounted on one circuit board, so that the increase in area, cost, design time, and manufacturing time becomes so large that it cannot be ignored.

  The objective of this invention is providing the circuit board and electronic device which can suppress the noise which propagates a signal wiring, without mounting components on a circuit board.

The present invention has two or more wiring layers,
In the two or more wiring layers, a signal wiring, a ground wiring arranged in parallel to the signal wiring, and a linear conductor are formed,
The signal wiring is arranged in a first wiring layer of the two or more wiring layers,
The linear conductor is a second wiring layer different from the first wiring layer among the two or more wiring layers so that at least a part of the linear conductor and a part of the signal wiring overlap each other vertically. Arranged,
The circuit board is characterized in that the linear conductor is connected to the ground wiring, and at least one end of the linear conductor is an open end.

The present invention also includes a circuit board,
The circuit board is
Having two or more wiring layers,
In the two or more wiring layers, a signal wiring, a ground wiring arranged in parallel to the signal wiring, and a linear conductor are formed,
The signal wiring is arranged in a first wiring layer of the two or more wiring layers,
The linear conductor is a second wiring layer different from the first wiring layer among the two or more wiring layers so that at least a part of the linear conductor and a part of the signal wiring overlap each other vertically. Arranged,
Provided is an electronic device in which the linear conductor is connected to the ground wiring, and at least one end of the linear conductor is an open end.

  According to the present invention, noise propagating through a signal wiring can be suppressed without mounting a component on a circuit board.

  The above-described object and other objects, features, and advantages will become more apparent from the preferred embodiments described below and the accompanying drawings.

It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 1st embodiment. It is an equivalent circuit of the noise suppression structure of the circuit board according to the first embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on the modification of 1st embodiment. It is a typical perspective view showing an example of a circuit board concerning a first embodiment. It is a figure which shows the result of having performed the electromagnetic field analysis by the three-dimensional electromagnetic field simulator about the transmission characteristic of signal wiring. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 2nd embodiment. It is an equivalent circuit of the noise suppression structure of the circuit board which concerns on 2nd embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on the modification of 2nd embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 3rd embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 4th embodiment. It is an equivalent circuit of the noise suppression structure of the circuit board which concerns on 4th embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 5th embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 6th embodiment. It is a typical disassembled perspective view which shows the noise suppression structure of the circuit board which concerns on 7th embodiment. It is a mimetic diagram of electronic equipment which has a circuit board concerning a first embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[First embodiment]
FIG. 1 is a schematic exploded perspective view showing a configuration of a circuit board 10 according to the first embodiment.

  The circuit board 10 according to the present embodiment has two or more wiring layers. In FIG. 1, two of the two or more wiring layers, that is, the first wiring layer 11 and the second wiring layer 12 different from the first wiring layer 11 are shown. The circuit board 10 may have only two wiring layers or may have three or more wiring layers. In these two or more wiring layers, a signal wiring 13, a ground wiring 14 arranged in parallel to the signal wiring 13, and a resonance line (linear conductor) 16 are formed. The signal wiring 13 is arranged in the first wiring layer 11. The resonance line 16 is disposed in the second wiring layer 12 so that at least a part of the resonance line 16 and a part of the signal wiring 13 overlap each other. The resonance line 16 is connected to the ground wiring 14, and at least one end 161 of the resonance line 16 is an open end that is not connected to any conductor. Details will be described below.

  In the case of this embodiment, the signal wiring 13 and the ground wiring 14 are formed in parallel on the first wiring layer 11 which is one wiring layer of the plurality of wiring layers of the circuit board 10, and the ground wiring 14 is It is arranged adjacent to the signal wiring 13. More specifically, the signal wiring 13 and the ground wiring 14 extend in parallel to each other.

  A resonance line 16 is formed in the second wiring layer 12 which is one wiring layer different from the first wiring layer 11 among the plurality of wiring layers of the circuit board 10. The resonance line 16 is arranged on the second wiring layer 12 so that at least a part of the resonance line 16 and a part of the signal wiring 13 overlap each other vertically (in the stacking direction of the plurality of wiring layers). In the case of the present embodiment, for example, the resonance line 16 overlaps the signal wiring 13 in the vertical direction over the entire region in the extending direction.

  The resonance line 16 extends in parallel with the signal wiring 13, for example. That is, the resonance line 16 extends in the same direction as the signal wiring 13.

  In the case of the present embodiment, the resonance line 16 is connected to the ground wiring 14 via the ground connection line 17 and the interlayer connection via 15.

The ground connection line 17 is disposed in the second wiring layer 12. For example, the ground connection line 17 extends in a direction orthogonal to the extending direction of the resonance line 16. One end 171 of the ground connection line 17 is connected to an end 162 of the resonance line 16 opposite to the end 161. The ground connection line 17 is formed integrally with the resonance line 16. The interlayer connection via 15 connects the other end 172 of the ground connection line 17 and the ground wiring 14 to each other.
That is, the end 162 of the resonance line 16 opposite to the open end (end 161) is connected to the ground wiring 14.

  The resonance line 16 and the signal line 13 are insulated from each other.

  In the present embodiment, the first wiring layer 11 and the second wiring layer 12 are wiring layers adjacent to each other, but if another conductor is not formed between the signal wiring 13 and the resonance line 16. For example, another wiring layer may exist between the first wiring layer 11 and the second wiring layer 12.

  Note that, in the resonance line 16, the length in the extending direction of the signal wiring 13 in a region overlapping with the signal wiring 13 in the portion from the connection portion (end 162) to the open end (end 161) with respect to the ground wiring 14. Is 1/4 of the wavelength of the noise to be suppressed. In the present embodiment, the length from the end 162 to the end 161 of the resonance line 16 is ¼ of the wavelength of the noise to be suppressed.

  Next, the function of the circuit board 10 shown in FIG. 1 will be described with reference to FIG. FIG. 2 is an equivalent circuit of the circuit board 10.

  In the equivalent circuit of FIG. 2, the transmission line is divided and shown at the position of the end 161 of the resonance line 16 (position indicated by the dotted line AA ′ in FIG. 1).

  The element 21a of the equivalent circuit represents the portion on the left side of the dotted line AA ′ in the signal wiring 13 in FIG. 1, the element 21c represents the resonance line 16 in FIG. 1, and the element 21b represents the dotted line A in the ground wiring 14 in FIG. It represents the part on the left side of -A '. The three elements 21a, 21b, and 21c constitute a transmission line 21.

  Similarly, elements 22a and 22b of the equivalent circuit represent portions on the right side of the dotted line AA ′ in the signal wiring 13 and the ground wiring 14 in FIG. 1, respectively. The elements 22a and 22b constitute a coplanar pair line transmission line 22.

  In the transmission line 21, the resonance line 16 disposed below the signal line 13 and the ground line 14 disposed beside the signal line 13 function as a reference signal line. A return current flows through the resonance line 16 and the ground wiring 14 in the direction opposite to the signal current flowing through the signal wiring 13.

  Here, it is assumed that the resonance line 16 has a larger area facing the signal line 13 than the ground line 14 and the resonance line 16 is closer to the signal line 13 than the ground line 14. That is, the wiring in each wiring layer has a larger width (dimension in the direction orthogonal to the extending direction of the wiring and in the direction perpendicular to the thickness direction) than the thickness (dimension in the wiring layer stacking direction). And In addition, the distance between the wirings that overlap each other in the adjacent wiring layer (specifically, the distance between the signal wiring 13 and the resonance line 16) is the distance between the adjacent wirings in the same wiring layer (specifically, Specifically, it is shorter than the distance between the ground wiring 14 and the signal wiring 13.

  For this reason, the electric field coupling between the resonance line 16 and the signal wiring 13 is stronger than the electric field coupling between the ground wiring 14 and the signal wiring 13. Therefore, most of the return current flows through the resonance line 16. For this reason, the resonance line 16 mainly functions as the reference signal line, and the transmission line 21 functions as a stacked pair line having the signal wiring 13 and the resonance line 16 that overlap each other.

In the transmission line 21, the resonance line 16 is opened at the dotted line AA ′. Therefore, the dotted line BB ′ where the resonance line 16 is connected to the ground wiring 14 is the input end, and the dotted line AA ′. Can be regarded as a receiving end open line. The voltage V _{1 at} the dotted line BB ′ is defined as an incident voltage V _i , a voltage at the receiving end Vg, a resonance line length d, a phase constant β in the transmission line 21, and a complex coefficient j, When the transmission loss of the transmission line 21 is ignored, it can be expressed by the following formula (1).

V ₁ = j · V _g · cos (β · d) (1)

As can be seen from Equation (1) above, V ₁ = 0 at a frequency that is an odd multiple of d = λ / 4, and the signal does not propagate. In this way, in the circuit board 10 of the present embodiment, it is possible to remove a band of a signal having an odd multiple of the frequency where d = λ / 4 among the signals propagating through the coplanar line.

  The length d of the resonance line 16 can be designed from the following formula (2), where f is the noise frequency, c is the speed of light, and εr is the relative dielectric constant of the circuit board 10.

  Next, a method for manufacturing the circuit board 10 will be described. The circuit board 10 can be manufactured using the same material as a general circuit board. The base material of the circuit board 10 can be composed of, for example, an organic material (epoxy, polyimide, fluororesin, PPE resin, phenol resin, etc.), or an insulating material such as ceramic, glass, silicon, or composite material. As materials for the signal wiring 13, the ground wiring 14, the resonance line 16, and the ground connection line 17, conductors such as copper, silver, silver palladium, and gold can be used. The pattern of the signal wiring 13, the ground wiring 14, the resonance line 16, and the ground connection line 17 can be formed by using a technique such as etching or printing.

  FIG. 1 shows an example in which the interlayer connection via 15 is used to connect the ground wiring 14 and the ground connection line 17 and the ground connection line 17 is formed in the second wiring layer 12 like the resonance line 16. . However, the connection method between the resonance line 16 and the ground wiring 14 is not limited to this example, and a connection method such as a modification described below may be used.

FIG. 3 is a schematic exploded perspective view showing the configuration of the circuit board 10 according to a modification of the first embodiment.
As shown in FIG. 3, the end 162 of the resonance line 16 is extended to a region without the signal wiring 13, the interlayer connection via 15 is formed at the end 162, and the ground connection line 17 is formed in the first wiring layer 11. May be. One end 171 of the ground connection line 17 is connected to the ground wiring 14, and the other end 172 of the ground connection line 17 is connected to the end 162 of the resonance line 16 via the interlayer connection via 15. The ground connection line 17 is formed integrally with the ground wiring 14. For example, the ground connection line 17 is formed in an L shape including a portion located on an extension line of the ground wiring 14 and a portion orthogonal to the ground wiring 14 in a plan view.

  Even if the resonance line 16 is extended as shown in FIG. 3, the transmission line 21 (FIG. 2) constitutes only the portion where the signal wiring 13 and the resonance line 16 overlap each other, and the length d of the wavelength d Signal propagation is suppressed at a frequency of 1/4. Therefore, the ground connection structure (the extended portion of the resonance line 16, the interlayer connection via 15, and the ground connection line 17) does not affect the frequency at which noise is suppressed.

  1 and 3 show an example in which the width of the resonance line 16 is the same as the width of the signal wiring 13 and the resonance line 16 overlaps with the signal wiring 13 in the entire width direction in plan view. The present embodiment is not limited to this example. If the resonance line 16 is arranged so that the electric field coupling between the signal line 13 and the resonance line 16 is stronger than the electric field coupling between the signal line 13 and the ground line 14, the resonance line 16 is made wider than the signal line 13. The resonance lines 16 and the signal wirings 13 may have different widths from each other.

[Application Example of Circuit Board According to First Embodiment]
FIG. 4 is a schematic perspective view showing an application example of the circuit board 10 according to the first embodiment.

  Integrated circuits (LSIs (Large Scale Integration)) 42 to 45 are mounted on the circuit board 41. A signal wiring 46 and a ground wiring 47 are formed between the integrated circuit 42 and the integrated circuit 43, and a signal wiring 48 and a ground wiring 49 are formed between the integrated circuit 44 and the integrated circuit 45. A clock signal having a fundamental frequency component of 40 MHz is transmitted from the integrated circuit 42 to the integrated circuit 43, and a high-speed signal of 2 GHz is transmitted from the integrated circuit 44 to the integrated circuit 45.

  A part of the output signal of the integrated circuit 42 is coupled to the signal wiring 48 as noise 42a. The output signal of the integrated circuit 42 includes a frequency component that is a multiple of 40 MHz. Among the components included in the noise 42a, in particular, the 2 GHz component, which is a 50th harmonic of 40 MHz, becomes a factor that degrades the signal quality of the high-speed signal from the integrated circuit 44.

  In the circuit board 41, at least a part of the region C surrounded by the dotted line is composed of a noise suppression structure having the same configuration as that of the circuit board 10 shown in FIG. A portion in the region C in the signal wiring 46 corresponds to the signal wiring 13 in FIG. 1, and a portion in the region C in the ground wiring 47 corresponds to the ground wiring 14 in FIG.

  The circuit board 41 is a multilayer board having a relative dielectric constant (εr) of 4.4 and a dielectric loss tangent (tan δ) of 0.02. In the circuit board 41, the thickness of the interlayer board between the uppermost layer and the second wiring layer (second wiring layer counted from the uppermost layer) is, for example, 60 μm. In the circuit board 41, the thickness of conductors such as signal wirings 46 and 48, ground wirings 47 and 49, resonance lines (not shown in FIG. 4; see resonance line 16 in FIG. 1), ground plane, and the like is, for example, 20 μm. In the circuit board 41, the widths of the signal wirings 46 and 48, the ground wirings 47 and 49, and the resonance lines are, for example, 100 μm, and the interval between the lines is, for example, 100 μm. The total length of the signal wiring 46 and the ground wiring 47 is 30 mm. In the resonance line, the length in the extending direction of the signal line 46 from the connection part between the resonance line and the ground line 47 to the open end of the part overlapping the signal line 46 in the vertical direction is 20 mm.

  FIG. 5 shows the result of electromagnetic field analysis performed on the transmission characteristics of the signal wiring 46 using a three-dimensional electromagnetic field simulator. The horizontal axis in FIG. 5 is the frequency (GHz), and the vertical axis is the S parameter representing the signal characteristics of the signal wiring 46.

  The reflection loss S <b> 11 (solid line) indicates the ratio of the signal that is reflected from the integrated circuit 42 to the signal wiring 46 and returns to the integrated circuit 42. That is, the reflection loss S11 is expressed by using the amplitude of the signal input from the integrated circuit 42 to the signal wiring 46 as a denominator and the amplitude of the signal reflected from the signal wiring 46 and returning to the integrated circuit 42 as a numerator.

  The insertion loss S21 (dotted line) indicates the ratio of the signal reaching the integrated circuit 43 out of the signals output from the integrated circuit 42. That is, the insertion loss S21 is expressed by using the amplitude of the signal output from the integrated circuit 42 as a denominator and the amplitude of the signal input to the integrated circuit 43 as a numerator.

  At a resonant frequency of 2.0 GHz, the insertion loss S21 is remarkably reduced and the reflection loss S11 is increased. Therefore, this frequency component of the signal is not incident on the signal wiring 46 from the integrated circuit 42. Accordingly, the noise coupled from the signal wiring 46 to the signal wiring 48 does not include a 2.0 GHz component, and therefore this noise does not affect the 2 GHz signal component on the signal wiring 48. Thus, by forming the same structure as the circuit board 10 shown in FIG. 1 or FIG. 3 in the region C in FIG. 4, the integrated circuit among the harmonic components of the 40 MHz signal output from the integrated circuit 42. The noise of the component that affects the output signal 44 can be removed, and good signal transmission can be performed between the integrated circuit 44 and the integrated circuit 45.

  The integrated circuit 43 receives the component of the 40 MHz clock signal output from the integrated circuit 42 that has passed through the filter indicated by the insertion loss S21 in FIG. That is, the integrated circuit 43 receives a signal from which a harmonic component of an odd multiple of 2 GHz is removed from the 40 MHz clock signal, but the insertion loss S21 of 40 MHz passes through the signal wiring 46 with a loss of approximately 0 dB. As 43, a good clock signal can be received.

  FIG. 15 is a schematic diagram showing an electronic apparatus 150 having the circuit board 10 (or the circuit board 41) according to the first embodiment. The electronic device 150 is, for example, a mobile phone, a personal computer equipped with a wireless communication function, or a portable information terminal. The circuit board 10 (or the circuit board 41) is a circuit board such as a printed board of the electronic device 150, and is disposed in the housing 151 of the electronic device 150.

According to the first embodiment as described above, in the region where the resonance line 16 overlaps the signal line 13, the signal line 13 overlaps with the signal line 13 rather than the electric field coupling between the signal line 13 and the ground line 14 adjacent thereto. The electric field coupling with the resonance line 16 is stronger. For this reason, a transmission line is formed by the signal wiring 13 and the resonance line 16. This transmission line can be regarded as a receiving end open line with a location where the resonance line 16 and the ground wiring 14 are connected as an input end and a location where the resonance line 16 is open as a receiving end. At the frequency where the length of the transmission line is ¼ of the wavelength, the voltage at the input end is 0, so that signal propagation is suppressed. Therefore, by adjusting the length of the resonance line 16 according to the noise frequency, it is possible to attenuate the noise propagated through the signal wiring 13.
As described above, the circuit board 10 according to the present embodiment has a structure in which the noise suppression structure is accommodated in the wiring board. Therefore, compared to the technique of inserting a filter (low-pass filter) configured by a capacitor, an inductor, or the like into the signal wiring, The mounting area can be reduced.
In addition, since it is not necessary to mount an inductor or a capacitor on the substrate, it is possible to reduce component costs, component management costs, mounting man-hours and lead times, installation area, design time, and manufacturing time.

  Thus, in the present embodiment, the noise propagating through the signal line 13 can be removed without mounting components on the board. Therefore, the wiring board 10 can be downsized.

[Second Embodiment]
FIG. 6 is a schematic exploded perspective view showing the configuration of the circuit board 50 according to the second embodiment.

In the first embodiment, the example in which the resonance line 16 is arranged at the position where the interlayer connection via 15 is connected to the end of the ground wiring 14 has been described.
On the other hand, in the present embodiment, as shown in FIG. 6, the interlayer connection via 15 is connected to a portion between the both ends of the ground wiring 14 (hereinafter, a middle portion). That is, the portion between both ends of the resonance line 16 is connected to the ground wiring 14.

  FIG. 7 is an equivalent circuit of the circuit board 50.

  The difference between the equivalent circuit of FIG. 7 and the equivalent circuit of FIG. 2 is that in FIG. 7, each of the signal wiring 13 and the ground wiring 14 has elements 23a and 23b that are regions on the left side of the dotted line BB ′. ing. That is, in the equivalent circuit of FIG. 7, the transmission line 23 constituted by the elements 23 a and 23 b is connected to the transmission line 21 at a dotted line BB ′.

Even in such a configuration, the voltage V _{1 on} the dotted line BB ′ becomes V ₁ = 0 at a frequency that is an odd multiple of the frequency at which d = λ / 4, and the signal does not propagate. In this way, in the circuit board 50 according to the present embodiment as well, as in the first embodiment, among the signals propagated through the coplanar lines, signals having a frequency that is an odd multiple of the frequency at which d = λ / 4 is obtained. The band can be removed.
That is, according to the second embodiment, the same effect as the first embodiment can be obtained.
Further, in the second embodiment, since the interlayer connection via 15 is connected to the middle portion of the ground wiring 14, the resonance line 16 and the ground connection line in the circuit board 50 are compared with the first embodiment. The degree of freedom of the positions of 17 and the interlayer connection via 15 (the degree of freedom of arrangement) increases.

  FIG. 8 is a schematic exploded perspective view showing a configuration of a circuit board 60 according to a modification of the second embodiment. The circuit board 60 shown in FIG. 8 is different from the circuit board 50 shown in FIG. 6 in that it has a plurality of resonance lines. In the example of FIG. 8, two resonance lines 16 and 19 are provided on the circuit board 60. The resonance line 16 and the resonance line 19 are arranged in the second wiring layer 12. The resonance line 16 and the resonance line 19 are arranged apart from each other in the longitudinal direction of the signal wiring 13. The resonance line 19 is connected via the ground connection line 17 and the interlayer connection via 18 in the same manner as the resonance line 16 is connected to the ground wiring 14 via the ground connection line 17 and the interlayer connection via 15. It is connected to the ground wiring 14.

  In this case, each resonance line (for example, two resonance lines 16 and 19) independently exhibits a noise suppression effect, and frequency components of odd multiples of frequencies at which the lengths d1 and d2 are ¼ of the wavelength. Can be band-removed. Here, since d1 and d2 can be selected independently, two frequencies for suppressing signal propagation can be arbitrarily selected. Therefore, the noise components in the two bands can be removed by setting the length d1 of the resonance line 16 and the length d2 of the resonance line 19 to be different from each other.

[Third embodiment]
FIG. 9 is a schematic exploded perspective view showing the configuration of the circuit board 70 according to the third embodiment.

  As shown in FIG. 9, in the case of this embodiment, ground wirings 14a and 14b are arranged on both sides of the signal wiring 13 in the first wiring layer 11, and the signal wiring 13 and the ground wiring 14a on both sides thereof are arranged. , 14b constitute a coplanar line.

  The resonance line 16 is arranged on the second wiring layer 12 so as to overlap the signal line 13, and the resonance line 16 is connected to the two ground connection lines 17 at the end 162. One ground connection line 17 is connected to one ground wiring 14a via an interlayer connection via 15a, and the other ground connection line 17 is connected to the other ground wiring 14b via an interlayer connection via 15b. Yes.

  The function of the circuit board 70 according to the third embodiment can be explained by the equivalent circuit shown in FIG. 2 as in the first embodiment.

In the case of the present embodiment, the element 21b in FIG. 2 represents the region on the left side of the line AA ′ of both the ground wirings 14a and 14b, and the element 22b is more than the line AA ′ of both the ground wirings 14a and 14b. It represents the area on the right side. Even when there are ground wirings 14 a and 14 b on both sides of the signal wiring 13 as in the present embodiment, the resonance line 16 is formed so as to overlap the signal wiring 13, so that the ground wirings 14 a and 14 b and the signal wiring 13 are not connected. The coupling of the electric field between the resonance line 16 and the signal wiring 13 is stronger than the coupling of the electric field. Accordingly, the voltage V _{1 at} the dotted line BB ′ in FIG. 2 becomes V ₁ = 0 at a frequency that is an odd multiple of the frequency at which the length d of the resonance line 16 is d = λ / 4. Propagation can be suppressed.

  Thus, also by 3rd embodiment, the effect similar to 1st embodiment is acquired. The first embodiment is an example in which the present invention is applied to a structure in which one ground wiring 14 runs parallel to the signal wiring 13, whereas the third embodiment does not apply to the signal wiring 13. This is an example in which the present invention is applied to a structure in which two ground wirings 14a and 14b run side by side.

[Fourth embodiment]
FIG. 10 is a schematic exploded perspective view showing the configuration of the circuit board 80 according to the fourth embodiment.

  In the case of the present embodiment, the ground connection line 17 is connected to a portion between the both ends (the end 161 and the end 162) of the resonance line 16 (hereinafter referred to as a midway portion). The open end is not connected to a conductor.

  FIG. 11 is an equivalent circuit of the circuit board 80.

In FIG. 10, the right end of the region where the signal wiring 13 and the resonance line 16 overlap is separated by a dotted line AA ′, and the left end of the region where the signal wiring 13 and the resonance line 16 overlap is separated by a dotted line DD ′. A portion where the ground connection line 17 and the resonance line 16 are connected is separated by a dotted line BB ′.
In FIG. 11, an element 23a represents an area on the left side of the dotted line DD ′ in the signal wiring 13, an element 24a represents an area between the dotted line DD ′ and the dotted line BB ′ in the signal wiring 13. The element 21a represents a region between the dotted line BB ′ and the dotted line AA ′ in the signal wiring 13, and the element 22 a represents a region on the right side of the dotted line AA ′ in the signal wiring 13.
The element 23b represents a region on the left side of the dotted line DD ′ in the ground wiring 14, the element 24b represents a region between the dotted line DD ′ and the dotted line BB ′ in the ground wiring 14, and the element 21b. Represents a region between the dotted line BB ′ and the dotted line AA ′ in the ground wiring 14, and the element 22 b represents a region on the right side of the dotted line AA ′ in the ground wiring 14. The element 24c represents a region between the dotted line DD ′ and the dotted line BB ′ in the resonance line 16, and the element 21c is between the dotted line BB ′ and the dotted line AA ′ in the resonance line 16. Represents an area. The elements 23a and 23b constitute the transmission line 23, the elements 24a, 24b and 24c constitute the transmission line 24, the elements 21a, 21b and 21c constitute the transmission line 21, and the elements 22a and 22b transmit. The track 22 is configured.

Here, as in the first to third embodiments, the coupling between the signal wiring 13 and the resonance line 16 is stronger than the coupling between the signal wiring 13 and the ground wiring 14. Accordingly, it can be considered that the transmission line 24 is substantially constituted by the elements 24a and 24c, and the transmission line 21 can be regarded as constituted by the elements 21a and 21c. Accordingly, if the dotted line BB ′ is the input end, the transmission lines 24 and 21 can be regarded as transmission lines with the output end open. Therefore, at the frequency where d3 = λ / 4 or d4 = λ / 4, the dotted line BB voltages V ₁ is 0 in the 'propagation of the signal is suppressed. Here, d3 is an extending direction of the signal wiring 13 in a region overlapping with the signal wiring 13 in the resonance line 16 from the connection portion to the ground wiring 14 to one open end (end 162). Is the length of D4 is a part of the resonance line 16 extending from the connecting part to the ground line 14 to the other open end (end 161) in the extending direction of the signal line 13 in a region overlapping with the signal line 13 in the vertical direction. Length. Here, since d3 and d4 can be selected independently, two frequencies for suppressing signal propagation can be arbitrarily selected. That is, by setting d3 and d4 to different lengths, it is possible to remove noise components in two bands.
In this way, by connecting the ground connection line 17 to the middle portion of the resonance line 16 and opening both ends of the resonance line 16, signals of odd frequency components of two different frequencies are used as the basic frequencies. Can be removed.

[Fifth embodiment]
FIG. 12 is a schematic exploded perspective view showing the configuration of the circuit board 90 according to the fifth embodiment.

  In the circuit board 90 according to the present embodiment, a plurality of signal wirings and a plurality of resonance lines are formed. As shown in FIG. 12, the first wiring layer 11 includes a ground wiring 14 and a plurality of (for example, seven) signal wirings 13a, 13b, 13c, 13d, 13e, 13f, and 13g. It is formed to be in parallel. In the second wiring layer 12, a plurality of resonance lines 16a, 16b, 16c, 16d, 16e, 16f, and 16g (for example, the same number as the signal wirings 13a to 13g) are formed in parallel with each other. Here, each of the signal wirings 13a to 13g and each of the resonance lines 16a to 16g extend in the same direction (parallel to each other). Further, individual resonance lines 16a to 16g correspond to the individual signal wirings 13a to 13g. Specifically, for example, the signal wirings 13a to 13g and the resonance lines 16a to 16g have a one-to-one correspondence. Then, the resonance lines 16a to 16g and the signal wirings 13a to 13g corresponding to each other are arranged so that a part of each other overlaps each other.

  The resonance lines 16a to 16g are connected to the ground connection line 17 at one end thereof. The ground connection line 17 is connected to the ground wiring 14 through the interlayer connection via 15.

  In the case of the present embodiment, the equivalent circuits and functions of the signal wirings 13a to 13g are the same as those of the first embodiment, and the frequency component signal of which the length of each of the resonance lines 16a to 16g is λ / 4. Propagation is suppressed. Thus, the present invention can also be applied to a signal transmission system in which a plurality of signal wirings 13a to 13g are formed in parallel. Note that the lengths of the respective resonance lines 16a to 16g can be set independently, and can be designed to suppress the propagation of signals having different frequency components.

[Sixth embodiment]
FIG. 13 is a schematic exploded perspective view showing the configuration of the circuit board 100 according to the sixth embodiment. As will be described below, the circuit board 100 according to the present embodiment has differential signal wiring.

  As shown in FIG. 13, the signal wiring 33 a and the signal wiring 33 b are formed in parallel with each other on the first wiring layer 11 of the circuit board 100. These signal wiring 33a and signal wiring 33b constitute a differential pair (differential signal wiring). That is, the circuit board 100 has a first signal wiring (signal wiring 33a) and a second signal wiring (signal wiring 33b), and the first signal wiring and the second signal wiring are adjacent to each other. Thus, they are arranged in parallel to constitute a differential signal wiring.

On both sides of the differential signal wiring, a ground wiring 34a and a ground wiring 34b are formed in parallel with the signal wiring 33a and the signal wiring 33b.
These signal wirings 33a and 33b and ground wirings 34a and 34b constitute a coplanar differential line.

  Signals having the same amplitude and opposite phases are propagated to the signal wiring 33a and the signal wiring 33b. At the transmitting end and the receiving end of the signal wiring 33a and the signal wiring 33b, the difference between these signals is processed as a differential signal.

  On the other hand, in the second wiring layer 12 of the circuit board 100, a resonance line 36a and a resonance line 36b are formed. Among these, the resonance line 36a is disposed at a position overlapping with the signal wiring 33a in the vertical direction, and the resonance line 36b is disposed at a position overlapping with the signal wiring 33b in the vertical direction.

  The resonance line 36a and the resonance line 36b are connected to the ground connection line 17 at one end thereof. The ground connection line 17 is connected to the ground wiring 34a through the interlayer connection via 35a, and is connected to the ground wiring 34b through the interlayer connection via 35b. Here, the length d of the resonance line 36a and the length d of the resonance line 36b are equal to each other.

  Also in this embodiment, as in the first to fifth embodiments, out of the signals flowing in the signal wirings 33a and 33b, the odd number of the frequency at which the length d of the resonance lines 36a and 36b is 1/4 of the wavelength. Propagation of double frequency components is suppressed. Therefore, the signal component of the frequency is also removed from the differential signal which is the difference between the signals propagating on the signal wirings 33a and 33b. Since the resonance lines 36a and 36b affect only the signals on the overlapping signal wirings 33a and 33b, respectively, and do not affect each other, they are effective for both the common mode component and the differential mode component of the signal. Thus, by forming the resonance lines 36a and 36b so as to overlap with the signal lines 33a and 33b constituting the differential signal lines, it is possible to suppress noise propagating on the differential signal lines.

[Seventh embodiment]
FIG. 14 is a schematic exploded perspective view showing the configuration of the circuit board 110 according to the seventh embodiment.

  Similar to the sixth embodiment, the circuit board 110 according to the present embodiment includes signal wirings 33a and 33b that constitute differential signal wirings. Furthermore, ground wirings 34a and 34b are formed on both sides of the differential wiring signal, as in the sixth embodiment. Therefore, the circuit board 110 according to the present embodiment has a coplanar differential line as in the sixth embodiment.

In the case of this embodiment, the resonance line 36 formed in the second wiring layer 12 is different from the sixth embodiment in that it is arranged so as to overlap both the signal wirings 33a and 33b. That is, in the sixth embodiment, separate resonance lines 36a and 36b are arranged for the two signal wirings 33a and 33b, respectively, whereas in this embodiment, the common resonance line 36 is arranged.
That is, the plurality of signal wirings 33a and 33b are formed in the same wiring layer (the first wiring layer 11), and the resonance line 36 overlaps with the plurality of signal wirings 33a and 33b in the vertical direction.

  In such a structure, only the common mode component is removed from the signal flowing through the differential signal wiring having the frequency for band removal, and the differential mode component is not affected. Hereinafter, this reason will be described.

  A transmission line through which a high-speed signal propagates is composed of a pair of a signal wiring through which a signal flows and a reference wiring through which a return current flows. In the cross section, the potential on the signal wiring and the potential on the reference wiring are opposite to each other. In the case of a signal of a common mode component, that is, when a signal having the same phase flows through the two signal wirings of the differential pair, a reverse sign potential is generated on the resonance line, and a return current flows on the resonance line.

  However, in the case of a differential mode component signal, signals in opposite phases flow through the two signal wirings 33a and 33b of the differential pair, so that the resonance line 36 is connected to both signal wirings 33a and 33b as in the present embodiment. Since the potential of the resonance line 36 becomes 0 V, which is an intermediate value, the return current flows not on the resonance line 36 but on the signal wirings 33a and 33b. Therefore, for the differential mode signal, the resonance line 36 is merely a conductor having an intermediate potential, which is the same as if it does not exist, and thus does not suppress signal propagation.

  In this way, by forming the resonance line 36 so as to overlap both the signal wirings 33a and 33b, among the signals of frequency components that are odd multiples of the frequency at which the length of the resonance line 36 is 1/4 of the wavelength, It functions as a common mode band elimination filter that removes only the common mode component and passes the differential mode component.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are accept | permitted.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2012-204113 for which it applied on September 18, 2012, and takes in those the indications of all here.

Claims (10)

Having two or more wiring layers,
In the two or more wiring layers, a signal wiring, a ground wiring arranged in parallel to the signal wiring, and a linear conductor are formed,
The signal wiring is arranged in a first wiring layer of the two or more wiring layers,
The linear conductor is a second wiring layer different from the first wiring layer among the two or more wiring layers so that at least a part of the linear conductor and a part of the signal wiring overlap each other vertically. Arranged,
The circuit board, wherein the linear conductor is connected to the ground wiring, and at least one end of the linear conductor is an open end.   The circuit board according to claim 1, wherein the ground wiring is disposed in the first wiring layer and is disposed adjacent to the signal wiring. The ground wiring is disposed on both sides of the signal wiring,
The circuit board according to claim 2, wherein a coplanar line is configured by the signal wiring and the ground wiring on both sides thereof.   4. The circuit board according to claim 1, wherein an end of the linear conductor opposite to the open end is connected to the ground wiring. 5.   4. The circuit board according to claim 1, wherein a portion between both ends of the linear conductor is connected to the ground wiring. 5. A plurality of each of the signal wiring and the linear conductor are formed,
Each of the signal wirings and each of the linear conductors extend in the same direction,
The individual linear conductors correspond to the individual signal wirings,
6. The circuit board according to claim 1, wherein the linear conductor and the signal wiring corresponding to each other are arranged so as to overlap each other. A plurality of the signal wirings are formed in the same wiring layer,
6. The circuit board according to claim 1, wherein the linear conductor overlaps vertically with respect to any of the plurality of signal wirings. 7. The first signal wiring and the second signal wiring,
8. The circuit board according to claim 6, wherein the first signal wiring and the second signal wiring are arranged adjacent to each other in parallel to constitute a differential signal wiring.   In the linear conductor, in the portion from the connection portion to the open end to the open end, the length in the extending direction of the signal wiring in the region overlapping with the signal wiring is the noise to be suppressed. The circuit board according to any one of claims 1 to 8, wherein the circuit board has a quarter wavelength. Having a circuit board,
The circuit board is
Having two or more wiring layers,
In the two or more wiring layers, a signal wiring, a ground wiring arranged in parallel to the signal wiring, and a linear conductor are formed,
The signal wiring is arranged in a first wiring layer of the two or more wiring layers,
The linear conductor is a second wiring layer different from the first wiring layer among the two or more wiring layers so that at least a part of the linear conductor and a part of the signal wiring overlap each other vertically. Arranged,
The electronic device, wherein the linear conductor is connected to the ground wiring, and at least one end of the linear conductor is an open end.

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