JP2006135064A - Printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed circuit board for stably supplying radio frequency currents to a device, reducing ripple noise of a power supply, and controlling the generation of common mode noise by mounting a device such as an IC to operate in comparativly higher speed and decoupling the power supply with optimum layout of a capacitor. <P>SOLUTION: A power supply terminal of the IC1 and one end of the capacitor 2 are connected with the wire 3 of the minimum distance for mounting the IC1 and capacitor 2, and one end of the capacitor 2 is connected with the wire 4 longer than the wire 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printed circuit board, and more particularly to a printed circuit board that performs power supply decoupling of a device using a capacitor.

  2. Description of the Related Art In recent years, integration of ICs (Integrated Circuits) and ASICs (Application Specific Integrated Circuits) and higher frequencies of signals for operating the electronic devices have been promoted along with higher functionality and higher performance of electronic devices.

  However, the integration and higher frequency of ICs and the like increase the high-frequency current in the circuit, leading to an increase in radiation noise. For this reason, in addition to reducing noise in the power line and decoupling the bypass capacitor to reduce common mode radiation noise, in addition to reducing normal mode radiation noise Various measures are taken.

For example, in the technologies described in Patent Document 1 and Patent Document 2, the power supply layer and the ground layer of the printed circuit board are not connected to the first power supply pattern and the first ground pattern that connect the bypass capacitor and the IC, respectively. The power supply layer is connected to one end of the bypass capacitor via the via hole and the second power supply pattern, and the ground layer is connected to the other end of the bypass capacitor via the via hole and the second ground pattern. When high-frequency current flows between the capacitor and the IC, high-frequency voltage ripple is prevented from occurring between the power supply layer and the ground layer, and as a result, electromagnetic noise radiated from the printed circuit board can be reduced. Yes.
JP 2000-91785 A JP 2000-156548 A

  However, in the configurations described in Patent Document 1 and Patent Document 2, since the distance between the IC and the bypass capacitor becomes long, it is a noise countermeasure for an IC that operates at a relatively low speed (about 10 MHz external clock). However, in a circuit on which an IC that operates at a relatively high speed (external clock of 40 to 50 MHz or more) is mounted, noise removal efficiency may be reduced.

  Further, in this configuration, the wiring area becomes large due to the power supply pattern and the ground pattern, which is not suitable for high-density mounting, and there is a concern about the occurrence of a voltage drop due to the inductance component of these patterns.

  Therefore, the present invention mounts a device such as an IC that operates at a relatively high speed and performs decoupling of the power supply by optimal arrangement of capacitors, thereby stably supplying a high-frequency current to the device, reducing ripple noise of the power supply, Furthermore, it aims at providing the printed circuit board which can suppress generation | occurrence | production of common mode noise.

  In order to achieve the above-described object, the invention of claim 1 is a printed circuit board having a power supply layer and a ground layer and performing power supply decoupling of a device using a capacitor, wherein the power supply terminal of the device and the capacitor Is connected with a first printed pattern having a minimum distance that allows the device and the capacitor to be mounted, and between the one end of the capacitor and the power supply layer by the first printed pattern. Also, a long second print pattern is used for connection.

  The invention of claim 2 is the invention of claim 1, wherein the ground terminal of the device and the other end of the capacitor are connected by a third print pattern having the same length as the first print pattern. The other end of the capacitor is connected to the ground layer through a via.

  According to a third aspect of the invention, in the first aspect of the invention, the ground terminal of the device and the ground layer are connected via a via, and the other end of the capacitor and the ground layer are connected via a via. It is characterized by connecting.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the other end of the capacitor and the ground layer are connected through a plurality of vias.

  According to a fifth aspect of the present invention, there is provided a solid ground according to the third aspect, wherein the via connecting the ground terminal of the device and the ground layer, and the via connecting the other end of the capacitor and the ground layer. The connection is made with a fourth print pattern formed as follows.

  According to a sixth aspect of the present invention, there is provided a printed circuit board having a power supply layer and a ground layer, wherein the power supply decoupling of the device is performed using a capacitor. The capacitor is disposed at a minimum distance from which the device and the capacitor can be mounted from the power supply terminal side of the printed pattern.

  According to a seventh aspect of the present invention, there is provided a printed circuit board having a power supply layer and a ground layer, and performing power supply decoupling of the device using a capacitor, between the power supply terminal of the device and one end of the capacitor. A first printed pattern for connecting the device and the capacitor at a minimum distance that can be mounted, and a second printed pattern for connecting between one end of the capacitor and the power supply layer, The second print pattern is longer than the first print pattern.

  According to the present invention, since the power supply terminal of the device and one end of the capacitor are connected with a printed pattern having a minimum distance that can be mounted, the supply of high-frequency current to the device is stable. Ripple noise can also be reduced, the high-frequency loop area related to the generation of radiation noise is minimized, and the generation of noise can be suppressed.

  Hereinafter, an embodiment of a printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram for explaining the concept of the present invention. In the present invention, the length of the wiring 3 that connects the IC (including ASIC, LSI (Large Scale Integration), etc.) 1 and the decoupling capacitor 2, that is, the mounting distance of the capacitor 2 with respect to the IC 1 is minimized. The length of the wiring 3 is actually the minimum length determined by the restrictions of the component mounting machine (insert machine). Further, the length of the wiring 4 connecting the power source side and the capacitor 2 is made longer than the length of the wiring 3. As a result, the area of the high-frequency loop indicated by arrow A in the figure is minimized, and stable supply of high-frequency current and reduction of radiation noise are achieved.

  Specific mounting methods of the IC 1 and the capacitor capacitor 2 will be described in the following embodiments.

  In the configuration described in the first embodiment, as shown in FIG. 2, the power pin 11 of the IC 1 and one end of the capacitor 2 are connected by a pattern 31 on the printed circuit board, and the ground pin 12 of the IC 1 and the other end of the capacitor 2 are connected. Are connected by a pattern 51 on the printed circuit board. Each of the pattern 31 and the pattern 51 is the minimum length determined by the restrictions of the component mounter.

  Of the terminals of the capacitor 2, the terminal connected to the power supply pin 11 is connected to the power supply layer of the printed circuit board via the pattern 41 and the via 42 on the printed circuit board. The side connected to the ground pin 12 is connected to the ground layer of the printed circuit board via the via 52. Neither IC1 nor capacitor 2 is connected to a solid ground 61 formed on the surface of the printed circuit board.

  FIG. 3 is a diagram showing an equivalent circuit of the configuration shown in FIG. In the equivalent circuit shown in the figure, an element indicated by reference numeral 20 is an equivalent circuit of the capacitor 2, and elements indicated by reference numerals L31, L41, L42, L51, and L52 are a pattern 31, a pattern 41, a via 42, and a pattern, respectively. 51 and inductance components of the via 52 are shown.

  In this configuration, the high frequency loop related to the generation of radiation noise includes an inductance component L31 and an inductance component L51 in addition to the capacitor 2.

  In the configuration described in the second embodiment, as shown in FIG. 4, the power supply pin 11 of the IC 1 and one end of the capacitor 2 are connected by a pattern 32 on a printed board. This pattern 32 is the minimum length determined by the restrictions of the component mounter. Of the terminals of the capacitor 2, the terminal connected to the power supply pin 11 is connected to the power supply layer of the printed circuit board via the pattern 43 and the via 44 on the printed circuit board.

  On the other hand, the ground pin 12 of the IC 1 is connected to the ground layer of the printed board through the via 53, and the other end of the capacitor 2 is connected to the ground layer of the printed board through the via 54 and the via 55. However, when it is difficult to connect the terminal of the capacitor 2 to the ground layer of the printed board via both the via 54 and the via 55, the connection may be made via either one.

  Neither IC1 nor capacitor 2 is connected to a solid ground 62 formed on the surface of the printed circuit board.

  FIG. 5 is a diagram showing an equivalent circuit of the configuration shown in FIG. In the equivalent circuit shown in the figure, the element indicated by reference numeral 20 is an equivalent circuit of the capacitor 2, and the elements indicated by reference numerals L32, L43, L44, L53, L54, and L55 are the pattern 32, pattern 43, and via 44, respectively. , The inductance components of the via 53, the via 54, and the via 55 are shown.

  In this configuration, the high-frequency loop related to the generation of radiation noise includes the inductance component L32, the inductance component L53, the inductance component L54, and the inductance component L55 in addition to the capacitor 2.

  In the configuration described in the third embodiment, as shown in FIG. 6, the power supply pin 11 of the IC 1 and one end of the capacitor 2 are connected by a pattern 33 on a printed board. This pattern 33 is the minimum length determined by the restrictions of the component mounter. Of the terminals of the capacitor 2, the terminal connected to the power supply pin 11 is connected to the power supply layer of the printed circuit board via the pattern 45 and the via 46 on the printed circuit board.

  On the other hand, the ground pin 12 of the IC 1 and the other end of the capacitor 2 are connected to a solid ground 63 formed on the surface of the printed circuit board. However, since the solid ground 63 is unstable in noise because it is formed on the surface layer of the printed circuit board, the solid ground 63 is connected to the ground layer of the printed circuit board via the via 64 in the vicinity of the ground pin 12. In the vicinity of the capacitor 2, the solid ground 63 and the ground layer of the printed circuit board are connected via the via 65 and the via 66. When it is difficult to form both the via 65 and the via 66, only one of them may be formed.

  FIG. 7 is a diagram showing an equivalent circuit of the configuration shown in FIG. In the equivalent circuit shown in the figure, the element indicated by reference numeral 20 is an equivalent circuit of the capacitor 2, and the elements indicated by reference numerals L33, L45, L46, L63, L64, L65, and L66 are the pattern 33, pattern 45, and The inductance components of the via 46, the solid ground 63, the via 64, the via 65, and the via 66 are shown. Reference numeral L67 represents an inductance component of another via that connects the solid ground 63 and the ground layer of the printed circuit board.

  In this configuration, in addition to the capacitor 2, the high-frequency loop related to the generation of radiation noise includes an inductance component L33, an inductance component L64, an inductance component L65, and an inductance component L66.

It is a figure for demonstrating the concept of this invention. 3 is a diagram for explaining a configuration of a printed circuit board in Embodiment 1. FIG. FIG. 3 is a diagram illustrating an equivalent circuit having the configuration illustrated in FIG. 2. 6 is a diagram for explaining a configuration of a printed circuit board in Embodiment 2. FIG. FIG. 5 is a diagram illustrating an equivalent circuit having the configuration illustrated in FIG. 4. FIG. 10 is a diagram for explaining a configuration of a printed circuit board in Example 3. It is the figure which showed the equivalent circuit of the structure shown in FIG.

Explanation of symbols

1 IC
2 capacitor 3 wiring 4 wiring 11 power supply terminal 12 ground terminal 20 capacitor equivalent circuit 31 pattern 32 pattern 33 pattern 41 pattern 42 via 43 pattern 44 via 45 pattern 46 via 51 pattern 52 via 53 via 54 via 55 via 61 solid ground 62 solid ground 63 Solid ground 64 Via 65 Via 66 Via L31 Inductive component L32 Inductive component L33 Inductive component L41 Inductive component L42 Inductive component L43 Inductive component L44 Inductive component L45 Inductive component L46 Inductive component L51 Inductive component L52 Inductive component L53 Inductive component L55 Inductive component L55 Inductive component L55 Inductance component L61 inductance component L62 inductance component L63 inductance component L64 inductance component L65 inductance component L66 inductance component L67 inductance component

Claims (7)

A printed circuit board having a power supply layer and a ground layer and performing power supply decoupling of a device using a capacitor,
The power terminal of the device and one end of the capacitor are connected by a first printed pattern with a minimum distance that can mount the device and the capacitor, and between the one end of the capacitor and the power layer. Are connected by a second print pattern longer than the first print pattern.   The ground terminal of the device and the other end of the capacitor are connected by a third print pattern having the same length as the first print pattern, and the other end of the capacitor and the ground layer are connected via a via. The printed circuit board according to claim 1.   The printed circuit board according to claim 1, wherein the ground terminal of the device and the ground layer are connected via vias, and the other end of the capacitor and the ground layer are connected via vias.   The printed circuit board according to claim 3, wherein the other end of the capacitor and the ground layer are connected via a plurality of vias.   A via that connects the ground terminal of the device and the ground layer, and a via that connects the other end of the capacitor and the ground layer are connected by a fourth printed pattern formed as a solid ground. The printed circuit board according to claim 3. A printed circuit board having a power supply layer and a ground layer and performing power supply decoupling of a device using a capacitor,
The power supply terminal of the device and the power supply layer are connected by a print pattern, and the capacitor is disposed at a minimum distance at which the device and the capacitor can be mounted from the power supply terminal side of the print pattern. Printed circuit board characterized by A printed circuit board having a power supply layer and a ground layer and performing power supply decoupling of a device using a capacitor,
A first printed pattern for connecting the power terminal of the device and one end of the capacitor at a minimum distance at which the device and the capacitor can be mounted;
A second printed pattern connecting between one end of the capacitor and the power supply layer,
The printed circuit board, wherein the second printed pattern is longer than the first printed pattern.

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