JP2008091707A - Wiring board device and its transmission characteristic correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce influence on transmission characteristics by a through-hole becoming an open stab. <P>SOLUTION: A transmission line 14 for adjustment of a higher line impedance is connected to the other end of the through-hole stab 13 of a wiring board 10 and the other end of the transmission line is grounded. Then, the length of the transmission line 14 is determined so that the total length of the through-hole stab 13 and the transmission line 14 for the adjustment becomes λ/4 relative to a using wavelength λ. At the time, while the through-hole stab 13 is capacitive and functions as a band stop filter when the transmission line 14 for the adjustment is not connected, the configuration of equivalently connecting a band pass filter to the connection point of a transmission line 11 and a transmission line 12 by the through-hole stab 13 and the transmission line 14 for the adjustment is attained by connecting the transmission line 14 for the adjustment (short stab), and the adverse influence of the through-hole stab 13 is prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wiring board device having a through hole and a correction method for preventing an adverse effect of a stub caused by the through hole on circuit characteristics.

  Conventionally, in a wiring board device, there is a case where a through hole is provided in order to shorten the wiring (see, for example, Patent Document 1), but if the wiring is not passed through the through hole, the through hole is opened stub. End up. Since this open stub is usually close to the state where the content is connected, not only does transmission loss occur, but it also adversely affects the transmission characteristics of the substrate.

In particular, when the length of the through hole is λ / 4 with respect to the wavelength λ used, this will act as a band rejection filter. When transmission lines by wiring are connected in series and there is an open stub having the above-mentioned λ / 4 length at the connection point, this functions as a band rejection filter, and the influence on transmission characteristics is further increased.
JP-A-2005-026549

  As described above, in a wiring board having a through hole, the through hole may become an open stub and adversely affect transmission characteristics.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wiring board device that can reduce the influence of a through hole as an open stub on transmission characteristics and a method for correcting the transmission characteristics. And

  In order to achieve the above object, a wiring board device according to the present invention is configured as follows.

  (1) In a wiring board device in which a through hole for connecting a plurality of transmission lines of different layers is formed on a substrate, and the through hole is an open stub, the surface of the through hole to which the transmission line is not connected An adjustment transmission line having one end connected to the end and the other end grounded is provided. The length of the adjustment transmission line is the sum of the stub length of the through hole and the length of the adjustment transmission line. It is characterized in that it is adjusted to be λ / 4 with respect to the operating wavelength λ.

  (2) In a wiring board device in which a through hole for connecting a plurality of transmission lines of different layers is formed on a substrate, and the through hole is an open stub, the surface of the through hole to which the transmission line is not connected A first adjustment transmission line whose one end is connected to the end, and a second adjustment transmission line whose one end is connected to the other end of the first adjustment transmission line and whose other end is open. And the length of the first adjustment transmission line is adjusted so that the sum of the stub length of the through hole and the length of the first adjustment transmission line is λ / 4 with respect to the wavelength λ used. The length of the second adjustment transmission line is adjusted to be λ / 4.

  (3) In (1) or (2), the impedance of the transmission line for adjustment is higher than the impedance of each of the plurality of transmission lines.

  The transmission characteristic correction method for a wiring board device according to the present invention is configured as follows.

  (4) A through hole for connecting a plurality of transmission lines of different layers is formed on the substrate, and the through hole is used in a wiring board device that becomes an open stub, and the transmission line of the through hole is not connected A short stub is formed by connecting an adjustment transmission line whose one end is grounded to an end of the surface, and the length of the adjustment transmission line is set to the length of the stub of the through hole and the length of the adjustment transmission line. Is adjusted so that the total is λ / 4 with respect to the operating wavelength λ.

  (5) A through hole for connecting a plurality of transmission lines of different layers to each other is formed on the substrate, and the through hole is used in a wiring board device that becomes an open stub, and the transmission line of the through hole is not connected One end of the first adjustment transmission line is connected to the end of the surface, and the other end of the second adjustment transmission line whose one end is open is connected to the other end of the first adjustment transmission line. Then, an open stub is formed, and the length of the first adjustment transmission line is the sum of the length of the stub of the through hole and the length of the first adjustment transmission line λ / And adjusting the length of the second adjustment transmission line so as to be λ / 4.

  (6) In (4) or (5), the impedance of the transmission line for adjustment is higher than the impedance of each of the plurality of transmission lines.

  As described above, in the present invention, the adjustment transmission line is connected to the through hole to form a short stub or an open stub, and the length of the adjustment transmission line is designed according to the use wavelength. Flatten the transmission characteristics. Therefore, according to the present invention, it is possible to provide a wiring board device and a transmission characteristic correction method thereof that can reduce the influence of the through hole as an open stub on the transmission characteristic.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is an equivalent circuit diagram showing a first embodiment of a wiring board device according to the present invention. In FIG. 1, reference numeral 10 denotes a wiring board. For example, a signal transmission line 11 having an impedance of 50Ω and a signal transmission line 12 having an impedance of 50Ω are connected in series, and one end of the through-hole stub 13 is connected to an intermediate point between these transmission lines. Are connected. It is assumed that the length of the through-hole stub 13 is shorter than λ / 4 with respect to the used wavelength λ.

  The other end of the through-hole stub 13 of the wiring board 10 is increased in line impedance by a predetermined length, for example, an adjustment transmission line 14 of about 55Ω to 75Ω is connected, and the other end of the transmission line is grounded. Then, the length of the transmission line 14 is determined so that the total length of the through-hole stub 13 and the adjustment transmission line 14 becomes λ / 4 with respect to the used wavelength λ.

  At this time, the through-hole stub 13 is capacitive and functions as a band rejection filter when the adjustment transmission line 14 is not connected. However, by connecting the adjustment transmission line 14 (short stub), the through-hole stub 13 is connected. Thus, the adjustment transmission line 14 has a configuration in which a band-pass filter is equivalently connected to the connection point between the transmission line 11 and the transmission line 12, and the adverse effect of the through-hole stub 13 can be prevented.

  In particular, if the impedance of the adjustment transmission line 14 is adjusted, a bandpass filter having a flat transmission characteristic around the wavelength used can be obtained.

(Second Embodiment)
FIG. 2 is an equivalent circuit diagram showing a second embodiment of the wiring board device according to the present invention. In FIG. 2, reference numeral 20 denotes a wiring board, for example, a signal transmission line 21 with an impedance of 50Ω and a signal transmission line 22 with an impedance of 50Ω are connected in series, and a through-hole stub 23 is connected to an intermediate point between these signal transmission lines. One end is connected.

  The other end of the through-hole stub 23 of the wiring board 20 is connected to a first adjustment transmission line 24 having a predetermined length and a line impedance of, for example, about 55Ω to 75Ω. The second adjustment transmission line 25 is connected to the end. The other end of the second adjustment transmission line 25 is an open end.

  The length of the transmission line 24 is determined so that the total length of the through-hole stub 23 and the first adjustment transmission line 24 is λ / 4 with respect to the used wavelength λ. Further, as the second adjustment transmission line 25, for example, a line having a high line impedance of about 55 to 75Ω is used, and the length is λ / 4.

  Also in this embodiment, the through-hole stub 23, the first adjustment transmission line 24, and the second adjustment transmission line 25 serve as a band pass filter at the used wavelength, and adversely affect the transmission lines 21 and 22 on the wiring board. It becomes possible to prevent. In particular, if the impedance of the first adjustment transmission line 24 is adjusted, the filter characteristics of the bandpass filter can be flattened.

(Example 1)
FIG. 3 is a sectional view showing an example of a through-hole forming wiring board device having a conventional structure. In FIG. 3, reference numeral 100 denotes a substrate, and first and second signal transmission lines 101 and 102 having a length of 47.5 mm are formed on the surface of the substrate 100. The end portions of the transmission lines 101 and 102 are connected to first and second through holes 103 and 104 which are formed 47.5 mm apart. Here, it is assumed that the through holes 103 and 104 are connected to each other via a third signal transmission line 105 formed in the intermediate layer. When the thickness of the substrate 100 is 1.6 mm and the depth from the substrate surface to the intermediate layer, that is, the length of the signal transmission portions 103a and 104a of the through holes 103 and 104 is 0.2 mm, the stubs of the through holes 103 and 104 are obtained. The lengths of the portions (from the intermediate layer to the back surface) 103b and 104b are 1.4 mm. In FIG. 3, the ground layer is omitted. The unit is mm.

  FIG. 4 is an equalization circuit diagram showing a transmission line model of the apparatus shown in FIG. In FIG. 4, the first to third signal transmission lines 101, 102, 105 have a length L = 47.5 mm and an impedance Z0 = 50Ω, and the used portions 103a, 104a of the through holes 103, 104 have a length L. = 0.2 mm and impedance Z0 = 35Ω, and each stub portion 103b, 104b has L = 1.4 mm and impedance Z0 = 35Ω. The transmission characteristics at this time are as shown in FIG. 5, and the transmission characteristics are disturbed at a frequency of 10 GHz corresponding to the used wavelength λ, so that there is a large signal transmission loss.

  6 and 7 are a cross-sectional view and a transmission line model showing the structure when the invention described in the first embodiment is applied to the apparatus shown in FIG. 3 as Example 1 according to the present invention, respectively. It is an equalization circuit diagram shown. 6 and 7, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals.

  In the apparatus shown in FIG. 6, on the back side of the substrate 100, the adjustment transmission lines 201 and 202 are drawn out from the portions where the through holes 103 and 104 are formed, and are connected to the ground layer. It has a structure in which a short stub is connected. Here, assuming that the length from the through-hole connection position to the ground layer connection position of each transmission line 201, 202 is 2.78 mm and the impedance Z0 is 50Ω, the transmission line model is as shown in FIG. 104, the impedance Z0 of the used portions 103a and 104a is 50Ω, and the impedance Z0 of the stub portions 103b and 104b is 50Ω. As shown in FIG. 8, the transmission characteristic at this time becomes flat in the vicinity of a frequency of 10 GHz corresponding to the used wavelength λ. Therefore, signal transmission loss can be effectively reduced.

  Here, the impedance Z0 of the adjustment transmission lines 201 and 202 is selected to be 65Ω, which is higher than the impedance 50Ω of the signal transmission lines 101 and 102. At this time, in the transmission line model, as shown in FIG. 9, the impedance Z0 of the used portions 103a and 104a of the through holes 103 and 104 is 35Ω, and the impedance Z0 of the stub portions 103b and 104b is 35Ω. As shown in FIG. 10, the transmission characteristics at this time become further flat in the vicinity of a frequency of 10 GHz corresponding to the used wavelength λ. Therefore, signal transmission loss can be further effectively reduced. In this case, an appropriate amount of impedance adjustment is considered to be 55 to 75Ω.

(Example 2)
11 and 12 are a cross-sectional view and a transmission line model, respectively, showing a configuration when the invention described in the second embodiment is applied to the apparatus shown in FIG. 3 as Example 2 according to the present invention. It is an equalization circuit diagram shown. 11 and 12, the same parts as those in FIGS. 3 and 4 are denoted by the same reference numerals.

  In the apparatus shown in FIG. 11, on the back side of the substrate 100, the adjustment transmission lines 203 and 204 having one end opened from the formation portions of the through holes 103 and 104, and thereby open stubs are formed in the through holes 103 and 104. It has a connected structure. Here, assuming that the lengths of the transmission lines 203 and 204 are 7.4 mm and the impedance Z0 is 50Ω, the transmission line model is as shown in FIG. 12, and the impedances of the used portions 103a and 104a of the through holes 103 and 104 are as follows. Z0 is 50Ω, and the impedance Z0 of the stub portions 103b and 104b is 50Ω. As shown in FIG. 13, the transmission characteristics at this time become flat in the vicinity of a frequency of 10 GHz corresponding to the used wavelength λ. Therefore, signal transmission loss can be effectively reduced.

  Here, the impedance Z0 of the adjustment transmission lines 203 and 204 is selected to be 60Ω, which is higher than the impedance 50Ω of the signal transmission lines 101 and 102. At this time, as shown in FIG. 14, the transmission line model does not change because the impedance Z0 of the used portions 103a and 104a of the through holes 103 and 104 is 50Ω and the impedance Z0 of the stub portions 103b and 104b is 50Ω. As shown in FIG. 15, the transmission characteristic at this time becomes further flat in the vicinity of a frequency of 10 GHz corresponding to the used wavelength λ. Therefore, signal transmission loss can be further effectively reduced. In this case, the appropriate amount of impedance adjustment is considered to be 55 to 75Ω.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is an equalization circuit diagram showing a first embodiment of a wiring board device according to the present invention. The equalization circuit diagram which shows 2nd Embodiment of the wiring board apparatus based on this invention. Sectional drawing which shows the example of the through-hole formation wiring board apparatus by a conventional structure. FIG. 4 is an equalization circuit diagram showing a transmission line model of the apparatus shown in FIG. 3. The frequency characteristic figure which shows the transmission characteristic of the apparatus shown in FIG.3 and FIG.4. Sectional drawing which shows the structure at the time of applying the invention demonstrated in 1st Embodiment to the apparatus shown in FIG. 3 as Example 1 which concerns on this invention. FIG. 7 is an equalization circuit diagram showing a transmission line model of the apparatus shown in FIG. 6. The frequency characteristic figure which shows the transmission characteristic of the apparatus shown in FIG.6 and FIG.7. The equalization circuit diagram which shows the transmission line model which gave the improvement further to the said Example 1. FIG. The frequency characteristic figure which shows the transmission characteristic of the transmission line model shown in FIG. Sectional drawing which shows the structure at the time of applying the invention demonstrated in 2nd Embodiment to the apparatus shown in FIG. 3 as Example 2 which concerns on this invention. FIG. 12 is an equalization circuit diagram showing a transmission line model of the apparatus shown in FIG. 11. The frequency characteristic figure which shows the transmission characteristic of the apparatus shown in FIG.11 and FIG.12. The equalization circuit diagram which shows the transmission line model which gave the improvement further to the said Example 2. FIG. The frequency characteristic figure which shows the transmission characteristic of the transmission line model shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Wiring board | substrate, 11, 12 ... Signal transmission line, 13 ... Through-hole stub, 14 ... Transmission line for adjustment, 20 ... Wiring board, 21, 22 ... Transmission line, 23 ... Through-hole stub, 24 ... 1st adjustment 25, second adjustment transmission line, 100, substrate, 101, 102, 105, signal transmission line, 103, 104, through-hole, 103a, 104a, through-hole signal transmission part, 103b, 104b, through Hall stub portion, 201, 202, 203, 204... Transmission line for adjustment.

Claims (6)

In the wiring board device in which a through hole for connecting a plurality of signal transmission lines having different layers is formed on the substrate, and the through hole is an open stub,
An adjustment transmission line having one end connected to the end of the through hole and the other end grounded,
The length of the transmission line for adjustment is adjusted so that the sum of the stub length of the through hole and the length of the transmission line for adjustment is λ / 4 with respect to the use wavelength λ. apparatus. In the wiring board device in which a through hole for connecting a plurality of transmission lines having different layers is formed on the substrate, and the through hole is an open stub,
A first adjustment transmission line whose one end is connected to the end of the through hole, and a second adjustment line whose one end is connected to the other end of the first adjustment transmission line and whose other end is open A transmission line,
The length of the first adjustment transmission line is adjusted so that the sum of the stub length of the through hole and the length of the first adjustment transmission line is λ / 4 with respect to the wavelength λ used, The wiring board device, wherein the length of the second adjustment transmission line is adjusted to be λ / 4.   The wiring board device according to claim 1, wherein an impedance of the adjustment transmission line is higher than an impedance of each of the plurality of transmission lines. A through hole for connecting a plurality of transmission lines of different layers to each other is formed on the substrate, and the through hole is used in a wiring board device that becomes an open stub,
A short stub is formed by connecting an adjustment transmission line whose one end is grounded to an end portion of the surface of the through hole to which the transmission line is not connected,
The length of the adjustment transmission line is adjusted so that the sum of the stub length of the through-hole and the length of the adjustment transmission line is λ / 4 with respect to the operating wavelength λ. Transmission characteristics correction method. A through hole for connecting a plurality of transmission lines of different layers to each other is formed on the substrate, and the through hole is used in a wiring board device that becomes an open stub,
A second adjustment in which one end of the first adjustment transmission line is connected to an end of the surface of the through hole where the transmission line is not connected, and one end is open to the other end of the first adjustment transmission line. By connecting the other end of the transmission line for use, an open stub is formed,
Adjusting the length of the first adjustment transmission line so that the sum of the stub length of the through hole and the length of the first adjustment transmission line is λ / 4 with respect to the wavelength λ used; A method for correcting a transmission characteristic of a wiring board device, wherein the length of the second adjustment transmission line is adjusted to be λ / 4.   3. The method of correcting a transmission characteristic of a wiring board device according to claim 1, wherein the impedance of the adjustment transmission line is higher than the impedance of each of the plurality of transmission lines.

Images