JP2008147573A - Multilayer substrate device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer substrate device allowing a circuit device that is mounted on a multilayer substrate to reduce the effects of noise in the relationship with a ground layer. <P>SOLUTION: A second field-effect transistor 112 and capacitors 102 and 106 of a power system constituting a power supply circuit arranged in a wiring board 131 are grounded to a power system ground layer 104. On the other hand, a DC-DC converter control IC 115 and an external LSI 123 that are arranged on the wiring board 131 and are other circuits for mainly processing signals are connected with a general ground layer 119 as a layer different from the power system ground layer 104. The power system ground 104 and the general ground layer 119 are connected by a fourth via-hole 118 at the position where loop current 145 is hard to affect the circuits for processing signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer substrate apparatus composed of a plurality of layers, and more particularly to a multilayer substrate apparatus with reduced influence of noise.

  A switching regulator is a power supply circuit using a switching element, and is widely used in various electronic devices. There are various types of switching regulators for stabilizing the DC output, and a typical example is a PWM (Pulse Width Modulation) method. The PWM switching regulator uses a DC (Direct Current) -DC converter to smooth the AC input and convert it to direct current. After switching at high speed with the switching element, it is rectified and smoothed again to obtain the desired direct current. An output is obtained (see, for example, Patent Document 1).

For this reason, there is a problem that noise is easily emitted to the outside during high-speed switching. This problem occurs particularly when the switching regulator is incorporated in a multilayer substrate. One of the causes is that a ground (GND: GrouND) plane composed of a grounding copper foil layer disposed so as to be sandwiched between multilayer boards is largely related to an external circuit. That is, EMI (Electro Magnetic Interference) noise generated by switching of the power system ground of the DC-DC converter is easily emitted to the outside via the ground plane and easily affected. In addition, there is a problem that the switching regulator easily receives noise generated in other places via the ground plane.
JP 2001-197726 (paragraph 0012, FIG. 1)

  In order to alleviate such a problem, it is conceivable to provide a slit in a ground (GND) layer of a circuit portion such as a switching regulator so as to limit a range in which noise is generated by a current flow. However, if the area through which the current flows is limited by the slit, the amount of current flowing into the ground side through the ground layer may be limited, which may cause not only the power supply circuit but also other ground planes connected to the ground plane. A new problem arises that the circuit is also affected by grounding.

  As described above, the problem has been described by taking a multilayer board device in which a power supply circuit is incorporated in a multilayer board as an example. In some cases, other circuits were adversely affected.

  Accordingly, an object of the present invention is to provide a multilayer board device in which the circuit device mounted on the multilayer board can reduce the influence of noise such as EMI noise in relation to the ground layer.

  In the first aspect of the present invention, (a) a specific circuit component and a wiring board in which other circuit components are arranged in one layer, and (b) grounding formed as a layer different from the wiring board. A first ground layer; (c) a second ground layer for grounding formed as a layer different from the wiring board and the first ground layer; and (d) the specific circuit component described above of the wiring board. First grounding conductive means for electrically connecting the grounding side of the circuit board and the first ground layer; and (e) electrically connecting the grounding side of the other circuit components of the wiring board and the second ground layer. The second grounding conductive means to be connected is provided in the multilayer substrate apparatus.

  In other words, in the present invention, circuit components arranged in the same layer are classified into specific circuit components therein and other circuit components, and the specific circuit components are formed as layers different from the wiring board. The other circuit components are connected to the second ground layer for grounding formed as a layer different from the wiring board and the first ground layer. They are connected and grounded. In this way, by separating the specific circuit component from the grounded portion of the other circuit components, the influence of noise such as EMI noise generated when grounding together on the same ground layer is reduced.

  In the invention according to claim 2, (a) a specific circuit component and a wiring board in which other circuit parts are arranged in one layer, and (b) the wiring board is formed as a different layer, and each has different regions. A ground layer having a first ground region and a second ground region for grounding arranged as: (c) a ground side of the specific circuit component of the wiring board and a first ground region of the ground layer; First conductive means for grounding electrically connected to each other, and (d) a second ground for electrically connecting the ground side of the other circuit components of the wiring board to the second ground region of the ground layer. The multi-layer substrate apparatus is provided with a grounding conductive means.

  In other words, in the present invention, circuit components arranged in the same layer are classified into specific circuit components therein and other circuit components, and the specific circuit components are formed as layers different from the wiring board. The second circuit element is connected to the first ground region of the ground layer for grounding, and the other circuit components described above belong to the same ground layer but are arranged at positions different from the first ground region. They are connected to the ground area and grounded. In this way, by separating the ground location of a specific circuit component and other circuit components, the influence of noise such as EMI noise generated when grounding together in the same ground region is reduced.

  Here, in the case of a switching regulator, the specific circuit components are, for example, a switching element and a capacitor. The specific circuit component may be a power circuit component, and the other circuit components may be signal processing circuit components. Thus, by separating the circuit components that cause noise from the circuit components that perform noise-sensitive operations by the ground layer or the ground region, the influence of noise in the entire multilayer substrate device can be reduced.

  In many cases, the first ground layer and the second ground layer are connected and grounded by a third grounding conductive means. In this case, the third grounding conductive means is the first grounding means. Further, by grounding at one point or locally at the second ground layer, the influence of noise on the other circuit components can be suppressed. The same applies to the third grounding conductive means for the first ground region and the second ground region. Further, it is also effective to arrange the second grounding conductive means in a region where the influence of the loop current generated by the third grounding conductive means in the second ground layer is reduced. For example, the second grounding conductive means is arranged as far as possible from the third grounding conductive means.

  As described above, according to the present invention, the noise flowing into the ground layer or the ground region can be suppressed by a simple measure such as dividing the grounding locations of various circuit components arranged on the same wiring board into two types. The amount of noise radiated from the ground layer or the ground region can also be suppressed. Thereby, for example, a power supply circuit and a signal processing system circuit can be efficiently arranged on the multilayer substrate device, and it becomes easy to increase the integration rate of the entire circuit device while reducing the influence of noise.

  Hereinafter, the present invention will be described in detail with reference to examples.

  Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 shows a peripheral portion of a power source of a multilayer board device according to an embodiment of the present invention. In the multilayer substrate apparatus 100 of this embodiment, one end of an input capacitor 102 is connected to an input terminal (V _IN ) 101 connected to a power source (not shown). The other end of the input capacitor 102 is connected to a power system ground (GND) layer 104 via a first via (IVH: Interstitial Via Hole) 103. One end of an output capacitor 106 and one end of a coil 107 are connected to an output terminal (V _OUT ) 105 of the power supply circuit 100. The other end of the output capacitor 106 is connected to the power system ground layer 104 through the second via 108. Further, the first and second field effect transistors 111 and 112 are connected in series between the input terminal 101 and the power ground layer 104 via a third via 109 having one end connected to the power ground layer 104. Has been.

  The other end of the coil 107 is connected to a connection point between the source S of the first field effect transistor 111 and the drain D of the second field effect transistor 11. The two control terminals 116 and 117 of the DC-DC converter control IC 115 are connected to the switching control gates G of the first and second field effect transistors 111 and 112 one by one.

  Meanwhile, one end of the fourth via 118 is connected to the power ground layer 104 together with the first to third vias 103, 108, and 109. The other end of the fourth via 118 is connected to the general ground layer 119. The grounding terminal 121 of the DC-DC converter control IC 115 is directly connected to the general ground layer 119 by the earth line 122. An external LSI (Large Scale Integration) 123 is also directly connected to the general ground layer 119 through an earth line 124. The general ground layer 119 is grounded.

  In such a multilayer substrate apparatus 100, each component in the frame indicated by the alternate long and short dash line constitutes a power supply circuit 126 formed of a switching regulator. Therefore, the external LSI 123 is housed in the same wiring board (board) together with the power supply circuit 126, but is a circuit component different from the power supply circuit 126. The power system ground layer 104 and the general ground layer 119 are formed as layers different from the wiring board on which the power supply circuit 126 and the external LSI 123 are arranged. The power system ground layer 104 and the general ground layer 119 may be formed as a first ground region and a second ground region as physically separated regions in the same layer, but in this embodiment, different layers are used. It is formed as.

  Here, the power supply circuit 126 performs the following operation. The power supplied from the input terminal 101 is applied to the drain D of the first field effect transistor 111 after the noise between the power system ground layer 104 is absorbed by the input capacitor 102. In this state, an ON signal is input from the control terminal 116 of the DC-DC converter control IC 115 to the gate G of the first field effect transistor 111, and the drain D and the source S are turned ON. As a result, the charge flowing in from the input terminal 101 is accumulated in the coil 107 and the output capacitor 106.

  Next, the input of the on signal to the gate G of the first field effect transistor 111 is turned off, and instead, the control signal 117 of the DC-DC converter control IC 115 is turned on to the gate G of the second field effect transistor 112. When a signal is input, its drain D and source S are turned on. As a result, the charge charged in the previous cycle flows to a load (not shown) connected to the output terminal 105.

  The rectangular wave generated by repeating the circuit operation as described above using the DC-DC converter control IC 115 is smoothed by passing through the coil 107 and further smoothed by the output capacitor 106, and is loaded from the output terminal 105. To be supplied. The voltage appearing at the output terminal 105 is determined by the value of the resistance component of the load.

  In such a power supply circuit 126, a voltage appearing at a load connected to the output terminal 105 is fed back to the DC-DC converter control IC 115 via a circuit portion (not shown). The DC-DC converter control IC 115 compares this voltage with the voltage to be originally applied to the load, and controls the output section of the ON signal output from the two control terminals 116 and 117. As a result, the voltage output from the output terminal 105 is controlled to an optimum value.

  FIG. 2 conceptually shows a three-dimensional view of the power supply peripheral portion of the multilayer substrate apparatus shown in FIG. In FIG. 2, the same components as those in FIG. FIG. 2 shows only the portion related to FIG. 1 in the multilayer substrate apparatus.

  As shown in FIG. 2, each circuit component shown in FIG. 1 is arranged on a wiring board 131 forming a predetermined layer. Among these, the second field effect transistor 112, the DC-DC converter control IC 115, and the external LSI 123 are mounted in areas where the ground wiring patterns 141, 142, and 143 are formed, respectively. This is performed for the ground wiring patterns 141, 142, and 143.

In the figure, a power ground layer 104 is disposed below the layer on which the wiring board 131 is formed, and a general ground layer 119 is disposed further below. A relatively large amount of current flows between the source S of the second field effect transistor 112 and the power system ground layer 104. Therefore, a pair of third vias 109 ₁ and 109 ₂ are arranged between the ground wiring pattern 141 and the power ground layer 104, and correspond to a large current.

In addition, between the power ground layer 104 and the general ground layer 119, there are three third positions at positions where the influence of the loop current 145 is minimized on the DC-DC converter control IC 115 and the external LSI 123 grounded with the general ground layer 119. Four vias 118 _{1 to} 118 ₃ are provided in a concentrated manner locally, and corresponding to a large current by so-called single-point grounding.

  In the example shown in FIG. 2, the power system ground layer 104 is formed as a single layer, but may be formed as a plurality of layers. In this case, it is preferable that the plurality of power ground layers perform grounding using vias evenly.

  As described above, in the multilayer substrate apparatus 100 of the present embodiment, the power ground layer 104 is provided separately from the general ground layer 119. As a result, a loop current 145 of the ground line flows in the power system ground layer 104. Switching noise generated by the loop current 145 is transmitted from the power system ground layer 104 to the general ground layer 119 or the outside thereof. However, since the power system ground layer 104 and the general ground layer 119 are grounded at a single point by the fourth via 118, the influence of noise on the general ground layer 119 or noise on other external circuit portions is reduced. The impact can be minimized.

  In the embodiment, the layer substrate circuit including the switching regulator using the DC-DC converter control IC 115 has been described. However, in general, a circuit portion such as a power source that is a source of noise and the other circuit portions are grounded on a board. The present invention can be applied to the separation of the layers.

  In the embodiment, only one wiring board is shown, but the present invention can be similarly applied to various wiring boards having a plurality of layers. In this case, two types of ground layers or two types of ground regions may be provided for each wiring board, or a part or all of these ground layers or ground regions may be shared. Good.

It is a circuit diagram showing the power supply periphery part of the multilayer substrate apparatus in one Example of this invention. FIG. 2 is an explanatory diagram conceptually showing a power supply peripheral portion of the multilayer substrate device shown in FIG. 1 in a three-dimensional manner.

Explanation of symbols

100 multilayer substrate device 103 first via 104 power ground layer (first ground layer)
108 second via 109 third via 111 first field effect transistor 112 second field effect transistor 115 DC-DC converter control IC
118 Fourth via 119 General ground layer (second ground layer)
123 External LSI
126 Power supply circuit 131 Wiring board 141, 142, 143 Ground wiring pattern 145 Loop current

Claims (7)

A specific circuit component and a wiring board in which other circuit components are arranged in one layer;
A first ground layer for grounding formed as a layer different from the wiring board;
A second ground layer for grounding formed as a layer different from the wiring board and the first ground layer;
A first grounding conductive means for electrically connecting a ground side of the specific circuit component of the wiring board and the first ground layer;
A multilayer board device comprising: a grounding side of the other circuit components of the wiring board; and second grounding conductive means for electrically connecting the second ground layer. A specific circuit component and a wiring board in which other circuit components are arranged in one layer;
A ground layer having a first ground region and a second ground region for grounding, which are formed as layers different from the wiring board and are disposed as different regions,
First grounding conductive means for electrically connecting a ground side of the specific circuit component of the wiring board and the first ground region of the ground layer;
And a second grounding conductive means for electrically connecting a grounding side of the other circuit component of the wiring board to the second ground region of the ground layer. .   3. The multilayer board device according to claim 1, wherein the specific circuit component is a switching element and a capacitor constituting a switching regulator.   3. The multi-layer substrate apparatus according to claim 1, wherein the specific circuit component is a power system circuit component, and the other circuit components are signal processing circuit components.   2. The multilayer substrate device according to claim 1, wherein the first ground layer and the second ground layer are connected by a third grounding conductive means disposed locally.   3. The multilayer substrate device according to claim 2, wherein the first ground region and the second ground region are connected by a third grounding conductive means disposed locally.   6. The second grounding conductive means is disposed in a region of the second ground layer where an influence of a loop current generated by the third grounding conductive means is reduced. Multi-layer board device.

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