JP2000353895A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a printed wiring board in which a digital signal processing area and an analog signal processing area on the opposite sides of the board can take an overlapped arrangement and conventional restraints of mounting can be eliminated. SOLUTION: The printed wiring board comprises a GND layer 1 for digital circuit formed on the entire surface of one inner layer of the board, a GND layer 2 for analog circuit formed on the inner layer in an analog signal processing area contiguously to the GND layer for digital circuit, and signal lines 12 for transmitting signals from a digital circuit 11 on a part mounting plane 7 to an analog circuit 9 on the same plane. According to the structure, generation of resonance due to parallel plate mode, radiation noise and electromagnetic coupling between signal lines can be suppressed, the digital signal processing area and the analog signal processing area on the opposite sides of the board can take an overlapped arrangement and restraints of mounting can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board for suppressing electromagnetic noise generated from a substrate.

[0002]

2. Description of the Related Art A conventional printed wiring board will be described with reference to the drawings. FIG. 4 and FIG.
FIG. 1 is a diagram showing a configuration of a conventional printed wiring board disclosed in Japanese Patent Application Publication No. 0-190167.

In FIGS. 4 and 5, reference numeral 22 denotes a power supply layer;
3 is a GND layer, 24 is a GND layer, 25 is an analog signal processing area, 26 is an analog signal processing area, 27 is a digital signal processing area, 28 is a digital signal processing area, 29 is a front layer, 30 is a back layer, and 32 is a back layer. The wiring layer 33 is a wiring layer.

In FIG. 4, the digital signal processing area 27 and the analog signal processing area 25 are arranged so as not to be mixed in the surface layer 29, and the analog signal processing area 27 Processing area 26
And the analog signal processing area 25
The digital signal processing area 28 is arranged so as not to be located at the lower position. Further, in the inner layer, all the areas corresponding to the analog signal processing areas 25 and 26 and the
The ND layers 23 and 24 are grounded. Further, an area adjacent to the digital signal processing area 27 is a planar power supply layer 22.

FIG. 5 shows a case where the printed wiring board having the structure shown in FIG. 4 is composed of six or more layers. In this case, wiring layers 32 and 33 are further arranged between the power supply layer 22 and the GND layer 23 and the GND layer 24 inside the printed wiring board.

As described above, in a substrate in which the digital signal processing area and the analog signal processing area are separated, the digital signal processing area and the analog signal processing area on both surfaces of the substrate are prevented from overlapping with each other.
At least the inner layer portion adjacent to the component mounting surface (front and back surfaces) is a GND surface.

This prevents noise from entering the analog signal processing area from the power supply surface of the inner layer. Further, noise is prevented from entering the digital signal processing area into the analog signal processing area.

[0008]

In the above-mentioned conventional printed wiring board, noise is prevented from entering the analog signal processing area from the power supply surface of the inner layer or the digital signal processing area. However, in the case of a configuration with six or more layers, by arranging the signal lines in a layer between the GND layer and the power supply layer, resonance in the parallel plate mode by the GND layer and the power supply layer occurs, and radiation noise increases, and However, there is a problem that electromagnetic coupling occurs between these signal lines.

Also, the digital signal processing area and the analog signal processing area on both surfaces of the substrate are prevented from overlapping, and the digital signal processing areas and the analog signal processing areas are overlapped on both sides of the substrate. However, there is a problem that the digital signal processing area and the analog signal processing area on both surfaces do not overlap each other, which limits mounting.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a digital signal processing area and an analog signal processing area, and further includes a signal line connecting circuits between the two processing areas. In the printed wiring board provided, by arranging signal lines in a layer between the GND layer and the power supply layer, resonance in the parallel plate mode by the GND layer and the power supply layer occurs, thereby increasing radiation noise. It is an object of the present invention to obtain a printed wiring board capable of suppressing the occurrence of electromagnetic coupling between signal lines.

The present invention has been made in order to solve the above-mentioned problems, and can adopt a configuration in which a digital signal processing area and an analog signal processing area on both surfaces of a substrate are overlapped. It is an object of the present invention to obtain a printed wiring board which can eliminate restrictions on mounting.

[0012]

A printed wiring board according to the present invention processes a digital signal and an analog signal on the same substrate, and processes a digital signal in a digital signal processing area and an analog signal in the analog signal processing area. In the multi-layer substrate separated from the signal processing area, a digital circuit GND layer is disposed on the entire surface of one inner layer of the substrate; An analog circuit GND layer and a layer outside the substrate as viewed from the digital circuit GND layer;
And a signal line for transmitting a signal from a digital circuit on the component mounting surface to an analog circuit on the same surface.

Further, the printed wiring board according to the present invention comprises:
The digital still camera further includes a second digital circuit GND layer disposed so as to sandwich the analog circuit GND layer.

Further, the printed wiring board according to the present invention processes a digital signal and an analog signal on the same substrate, and has a digital signal processing area for processing the digital signal and an analog signal processing area for processing the analog signal. And a first digital circuit GND layer disposed on the entire surface of one inner layer of the substrate, and an inner layer of the analog signal processing area adjacent to the first digital circuit GND layer. Analog circuit GND layer, a second digital circuit GND layer disposed so as to sandwich the analog circuit GND layer, and one layer outside the substrate when viewed from the first digital circuit GND layer From the digital circuit on one component mounting surface to the analog circuit on the other component mounting surface. A.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A printed wiring board according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 1 of the present invention. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, 1 is a GN for a digital circuit.
D plane, 2 GND plane for analog circuit, 3 power supply plane for digital circuit, 4 layer of low-speed digital signal line or analog signal line, 5 layer of high-speed digital signal line, 6 and 7
Is a component mounting / wiring surface, 8 and 9 are analog circuits, 10 and 11 are digital circuits, and 12 is a signal line.

In FIG. 1, a GND plane 1 for a digital circuit, a GND plane 2 for an analog circuit, and a power supply plane 3 for a digital circuit are provided in an inner layer of the substrate. The outer surfaces of the substrate are the component mounting / wiring surfaces 6 and 7.

A signal line 12 between the digital circuit 11 and the analog circuit 9 (a signal line from the digital circuit 11 to the DA converter) is placed on the GND plane 1 side for the digital circuit. The digital circuit 11 and the analog circuit 9 are also placed on this surface. The high-speed digital signal line layer 5 is placed in the area of the digital circuit section.

On the other side 6, analog GND
The analog circuit 8 is placed in the area of the surface 2. A digital circuit 10 is provided on the digital GND plane 1.

Thus, the layer 5 of the high-speed digital signal line
And a signal line 12 between the digital circuit 11 and the analog circuit 9
Are wired on the digital GND plane 1. These signal lines are not wired on the joints of the GND planes for the analog signal processing area and the digital signal processing area. This can suppress an increase in radiation noise.

Further, between the digital GND plane 1 and the digital power supply layer 3, and between the digital GND plane 1 and the analog GND plane.
Since there is no digital signal line between the D layers 2, there is no resonance due to this, and an increase in radiation noise can be suppressed.

The analog circuit 8 has an analog GND
2, the analog circuits 8 and 9 do not necessarily have to overlap. This reduces restrictions on mounting.

In the printed wiring board according to the first embodiment, a digital signal processing area for processing digital signals and an analog signal processing for processing analog signals in a multilayer board for processing digital signals and analog signals on the same substrate. The digital GND1 (ground) is disposed on the entire surface of one inner layer of the substrate, and the analog GND2 is disposed on the inner layer of the analog signal processing area.
These GNDs are located on different layers adjacent to each other, and include signal lines 12 connecting between the two circuits for transmitting signals from the digital circuit 11 to the analog circuit 9. On the outer layer.

Embodiment 2 FIG. Embodiment 2 A printed wiring board according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 2 of the present invention.

In FIG. 2, 1 is a GN for a digital circuit.
D plane, 2 GND plane for analog circuit, 3 power supply plane for digital circuit, 4 layer of low-speed digital signal line or analog signal line, 5 layer of high-speed digital signal line, 6 and 7
Is a component mounting / wiring surface, 8 and 9 are analog circuits, 10 and 11 are digital circuits, and 12 is a signal line.

In FIG. 1, reference numeral 13 denotes a GND plane for a digital circuit, and reference numeral 14 denotes a high-speed digital signal line layer.

The printed wiring board according to the second embodiment is different from the wiring shown in FIG. 1 in that the GND planes 1 and 13 for the digital circuit in the inner layer of the substrate have the G plane
It has a structure in which a layer of the ND plane 2 and a power supply plane 3 for digital circuits is sandwiched.

Thus, the digital circuit 10 can be a high-speed digital circuit with respect to the wiring board shown in the first embodiment, and high-speed digital circuits can be placed on both sides of the wiring board. Further, the radiation noise from the digital power supply layer 3 can be electromagnetically shielded.

In FIG. 2, there is no need to overlap digital circuits and analog circuits located on both sides of the substrate.
The degree of freedom in mounting is increased. GND for digital circuits
By changing the ratio of the surface 13 to be closed, the side of the component mounting / wiring surface 6 can be used as a digital circuit area.

The printed wiring board according to the second embodiment has a digital GND layer 13 in a layer next to a certain layer of the analog GND 2 from the digital GND layer 1.

Embodiment 3 Embodiment 3 A printed wiring board according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 3 of the present invention.

In FIG. 3, 1 is a GN for a digital circuit.
D plane, 2 GND plane for analog circuit, 3 power supply plane for digital circuit, 4 layer of low-speed digital signal line or analog signal line, 5 layer of high-speed digital signal line, 6 and 7
Is a component mounting / wiring surface, 9 is an analog circuit, 10 and 11
Is a digital circuit.

In FIG. 1, reference numeral 13 denotes a GND plane for a digital circuit, and reference numeral 14 denotes a high-speed digital signal line layer.

Further, in the figure, 15 is a digital circuit, and 16 is a signal line.

As shown in FIG. 3, according to the third embodiment, when the signal line 16 connecting the digital circuit 11 and the analog circuit 9 crosses both sides of the wiring board, for example, the signal line 16 Is a case where the digital circuit 11 and the DA conversion circuit connected by the above are on the opposite surface of the substrate.

Also in this case, since the digital GNDs 1 and 13 are always provided below the main signal line 16, the signal line 16 is connected to the GND plane 2 for the analog signal processing area and the GND planes 1 and 13 for the digital signal processing area. Is not wired on the seam. An increase in radiation noise due to this defect can be suppressed.

The printed wiring board according to the third embodiment has a digital signal processing area for processing digital signals and an analog signal processing for processing analog signals in a multilayer substrate for processing digital signals and analog signals on the same substrate. The digital GND 1 is arranged on the entire surface of one inner layer of the substrate, and the analog GND 2 is arranged on the inner layer of the analog signal processing area.
D is a signal that connects two circuits for transmitting a signal from the digital circuit 11 to the analog circuit 9, wherein D is on a different layer adjacent to the next layer and has a digital GND layer 13 on the next layer separated from a certain layer of the analog GND 2. Lines 16, from which the signal lines extend from a layer outside the substrate when viewed from the digital GND layer 1.
Wired to the other layer.

[0038]

As described above, the printed wiring board according to the present invention processes a digital signal and an analog signal on the same substrate, processes a digital signal in a digital signal processing area for processing the digital signal, and processes the analog signal. In the multi-layer substrate in which the analog signal processing area is separated, a digital circuit GND layer is disposed on the entire surface of one inner layer of the substrate, and is disposed in the analog signal processing area adjacent to the digital circuit GND layer. And a signal line for transmitting a signal from the digital circuit on the component mounting surface to the analog circuit on the same surface, which is located on a layer outside the substrate when viewed from the GND layer for the digital circuit. , The generation of resonance due to the parallel plate mode, radiation noise, and the generation of electromagnetic coupling between signal lines can be suppressed. An analog signal processing section overlaps configuration can take an effect that it is possible to eliminate the restrictions on mounting.

Further, the printed wiring board according to the present invention comprises:
As described above, since the second digital circuit GND layer is further provided so as to sandwich the analog circuit GND layer, the occurrence of resonance in the parallel plate mode, radiation noise, and electromagnetic coupling between signal lines are reduced. Generation can be suppressed, and the digital signal processing area and the analog signal processing area on both sides of the substrate can be configured to overlap each other, so that there is an effect that mounting restrictions can be eliminated.

Further, as described above, the printed wiring board according to the present invention processes a digital signal and an analog signal on the same substrate, processes the digital signal, and processes the digital signal and the analog signal. In a multilayer board where the analog signal processing area is separated,
A first digital circuit GND layer disposed on the entire surface of one inner layer of the substrate; and an analog circuit GND layer disposed adjacent to the first digital circuit GND layer and disposed on an inner layer of the analog signal processing area. A second digital circuit GND layer disposed so as to sandwich the analog circuit GND layer, and a wiring from one layer outside the substrate as viewed from the first digital circuit GND layer to the other layer, Signal lines for transmitting signals from a digital circuit on one component mounting surface to an analog circuit on the other component mounting surface. Generation can be suppressed, and the digital signal processing area and the analog signal processing area on both sides of the substrate can be configured to overlap with each other, so that restrictions on mounting can be eliminated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 2 of the present invention.

FIG. 3 is a diagram showing a cross-sectional configuration of a printed wiring board according to Embodiment 3 of the present invention.

FIG. 4 is a diagram showing a cross-sectional configuration of a conventional printed wiring board.

FIG. 5 is a diagram showing a cross-sectional configuration of another conventional printed wiring board.

[Explanation of symbols]

1 GND plane for digital circuit, 2 GND plane for analog circuit, 3 power supply plane for digital circuit, 4 low-speed digital signal line or analog signal line layer, 5 high-speed digital signal line layer, 6, 7 parts Mounting / wiring surface, 8, 9
Analog circuits, 10, 11 digital circuits, 12 signal lines, 13 GND plane for digital circuits, 14 layers of high-speed digital signal lines, 15 digital circuits, 16 signal lines.

Continued on the front page (72) Inventor Yu Uchida 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Mitsuhiko Kanda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. In-house F-term (reference) 5E321 AA17 GG05 5E338 AA03 CC01 CC04 CC05 EE11 EE13 5E346 BB02 BB04 BB06 HH04

Claims (3)

[Claims] 1. A multi-layer substrate in which a digital signal and an analog signal are processed on the same substrate, and a digital signal processing area for processing the digital signal and an analog signal processing area for processing the analog signal are separated. For digital circuits arranged on the entire inner layer
An ND layer, an analog circuit GND layer adjacent to the digital circuit GND layer and disposed in an inner layer of the analog signal processing area, and a component mounting surface on a layer outside the substrate when viewed from the digital circuit GND layer. A signal line for transmitting a signal from an upper digital circuit to an analog circuit on the same surface. 2. The printed wiring board according to claim 1, further comprising a second GND layer for a digital circuit arranged so as to sandwich the GND layer for the analog circuit. 3. A multi-layer substrate in which a digital signal and an analog signal are processed on the same substrate, and a digital signal processing area for processing the digital signal and an analog signal processing area for processing the analog signal are separated. A first digital circuit GND layer disposed on the entire surface of one inner layer, and an analog circuit GND disposed adjacent to the first digital circuit GND layer and disposed on an inner layer of the analog signal processing area.
A second digital circuit GND layer disposed so as to sandwich the analog circuit GND layer, and wiring from one layer outside the substrate to the other layer as viewed from the first digital circuit GND layer. A signal line for transmitting a signal from a digital circuit on one component mounting surface to an analog circuit on the other component mounting surface.