JPH11224932A - Semiconductor integrated circuit and semiconductor integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit having an analog circuit and a digital circuit on the same substrate, without decreasing operating characteristics of the analog circuit. SOLUTION: An analog part A as an analog circuit and a digital part D as a digital circuit are separated as far as possible in distance. In addition, separating layers I1 and I2 for separating the analog part A and the digital part D are provided between these analog and digital parts A and D on the same semiconductor substrate Sub for forming these analog circuit and the digital circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor integrated circuit device having an analog circuit and a digital circuit, and more particularly to a device for controlling the operations of an analog circuit and a digital circuit by the same control circuit.

[0002]

2. Description of the Related Art Conventionally, noise generated from a digital circuit due to a clock or the like is mixed into an analog circuit, and as a result, the operating characteristics of the analog circuit are deteriorated. Is not formed on one semiconductor substrate, and the analog circuit and the digital circuit are separate chips.

For this reason, in a semiconductor integrated circuit device that requires an analog circuit and a digital circuit that are related to each other, the audio device is taken as an example.
As shown in FIG. 4, an audio circuit (analog circuit) 20 that performs a sound operation to drive the load in the load group 300 and a switch circuit (digital circuit) 30 that performs a switching operation to drive the load in the load group 300 Is controlled by a microcomputer (hereinafter abbreviated as “microcomputer”) 100 which is the same control circuit, the microcomputer 100 sends a control signal to the audio circuit 20 via a control line L 1 and a switch circuit 30 via a control signal. And two control lines L1 and L2.

[0004]

As described above, as long as the control line to the analog circuit and the control line to the digital circuit are separate, the operation of the analog circuit and the digital circuit due to external noise and the like is caused. The timing relationship may be out of order, which may lead to malfunction.In particular, the more circuits that need to be controlled by the microcomputer, the more control lines,
Regardless of the arrangement, as shown in FIG. 5, since the control line becomes long, the control line becomes susceptible to external noise, and the possibility of causing a malfunction increases.

In addition, as the number of circuits that need to be controlled by the microcomputer increases, more control ports are provided in the microcomputer 100 as shown in FIG. 6A, or as shown in FIG. As shown in FIG.
., Or control circuits 400-1 and 40 that receive a control signal from a microcomputer and control a plurality of circuits as shown in FIG.
0-2,... Need to be provided separately, and disadvantages increase in cost and circuit area. If a control circuit is separately provided, the number of control lines increases, and the possibility of malfunctions increases.

Accordingly, an object of the present invention is to provide a semiconductor integrated circuit in which an analog circuit and a digital circuit are formed on the same substrate without deteriorating the operating characteristics of the analog circuit.

Another object of the present invention is to provide a semiconductor integrated circuit device having an analog circuit and a digital circuit which are related to each other in operation content, which reduces the possibility of malfunction, reduces cost and circuit area. It is an object of the present invention to provide a semiconductor integrated circuit device realizing the above.

[0008]

In order to achieve the above object, in a semiconductor integrated circuit according to the present invention, an area between an analog section for forming an analog circuit and a digital section for forming a digital circuit is provided. As far as possible,
An analog circuit and a digital circuit are formed on a single semiconductor substrate after providing a separation layer between the analog section and the digital section for separating them from each other.

With the above configuration, an analog circuit and a digital circuit are formed on one semiconductor substrate, but a path through which noise generated from the digital circuit due to a clock or the like enters the analog circuit is cut off. .

In the semiconductor integrated circuit device according to the present invention,
In a semiconductor integrated circuit device having a plurality of circuits that are related to each other in operation content and a control circuit that controls operations of the plurality of circuits based on a common control signal,
Between the analog section, which is an area where an analog circuit of the plurality of circuits and the control circuit is formed, and the digital section which is an area where a digital circuit of the plurality of circuits and the control circuit is formed. As far as possible, a separation layer is provided between the analog section and the digital section to electrically separate the analog section and the digital section. It is formed on a semiconductor substrate.

According to the above configuration, only one control line is provided from the control circuit for outputting the control signal to the control circuit. Therefore, even if external circuits are affected, the operation timings of the plurality of circuits are the same. The number of control circuits is increased or the number of control ports of the control circuit is increased according to the number of circuits that need to be controlled. Or the need to provide another control circuit becomes unnecessary.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an audio device according to an embodiment of the present invention. In the figure, 1 is a control circuit, 2 is an audio circuit, 3 is a switch circuit, and an audio circuit 2 which is an analog circuit, and a control circuit 1 and a switch circuit 3 which are digital circuits are formed on one semiconductor substrate. The control circuit 1, the audio circuit 2, and the switch circuit 3 are one chip as the audio IC 200.

An audio circuit 2 drives a speaker 302 via a power amplifier 301 and a switch circuit 3
When the transistor 31 is turned on, the capacitor 303 is discharged, the terminal of the mute circuit 24 becomes the ground potential, and the volume is narrowed down by the volume circuit 23.
When the transistors 32 and 33 are turned on, the lamp 303 and the motor 304 are driven, respectively.

A control circuit 1 is a surround circuit 2 which forms an audio circuit 2 based on a control signal sent from a microcomputer 100 via a control line L.
1, control the operation of the tone circuit 22, the volume circuit 23, and the mute circuit 24, and
ON / OF of the transistors 31, 32, 33 constituting the
Switch F.

With the above configuration, the control line is only one control line L from the microcomputer 100 to the audio IC 200. Therefore, even if the control circuit L is affected by external noise, the control line L If one of the operation timings is shifted, the other is also shifted by the same amount, so that the relationship between the operation timings of the audio circuit 2 and the switch circuit 3 is not disrupted. Can be reduced.

As shown in FIG. 2, even if the number of audio circuits as analog circuits or the number of switch circuits as digital circuits is large, all circuits 202, 203, 204,
., Are controlled, and the control circuit 201 is mounted on one semiconductor substrate.
Is formed on a single semiconductor substrate, the chip area of the audio IC 200 naturally increases, but the microcomputer 100 transmits the audio IC 200 from the microcomputer 100 regardless of the number of circuits that need to be controlled. There is only one control line, and as in the past, the number of microcontroller control ports, or the number of microcontrollers, or external control It is not necessary to provide a circuit, so that cost reduction and circuit area reduction can be realized.

In the audio IC 200, as shown in the top view of FIG. 3A, an analog section A for forming an analog circuit (audio circuit 2) and a digital circuit (control circuit 1 and control circuit 1) are provided. Separation layers I1 and I2 are provided between the analog section A and the digital section D so as to separate the digital section D as much as possible from the area where the switch circuit 3) is formed. .

The structure will be specifically described with reference to the sectional view shown in FIG. P-type substrate (substrate) Su
N ⁺ type buried layers BL1, BL2, BL3, B
The N-type epitaxial layer Epi is formed by providing L4. The N ⁺ type buried layer BL3 has a ring shape surrounding the N ⁺ type buried layer BL4.

The N-type epitaxial layer Epi is formed of four regions Epi1 and Epi by three P-type layers each including a P-type well layer W and a P-type lower isolation layer LI.
2, Epi3 and Epi4. The N-type epitaxial layer Epi3 is an N-type epitaxial layer E.
It has a ring shape surrounding pi4.

An N ⁺ -type collector wall CW is formed in the N-type epitaxial layer Epi2 so as to be in contact with the buried layer BL2 and to have a ring shape.
Further, an N ⁺ -type contact layer SD is formed above the N ⁺ -type collector wall CW. The N ⁺ type contact layer SD is connected to the power supply voltage V _CC .

An N ⁺ -type collector wall CW is formed in the N-type epitaxial layer Epi3 so as to be in contact with the buried layer BL3.
Is formed with an N ⁺ -type contact layer SD. The collector wall CW2 has a ring shape like the N-type epitaxial layer Epi3. Also,
N ⁺ -type contact layer SD is connected to power supply voltage V _CC .

The N-type epitaxial layer Epi4 is separated into two regions Epi41 and Epi42 by a P-type layer composed of a P-type well layer W and a P-type lower isolation layer LI. The N-type epitaxial layer Epi41 has a ring shape surrounding the N-type epitaxial layer Epi42.

The analog section A is an N-type epitaxial layer Epi1 and the digital section D is an N-type epitaxial layer Epi42. Each has a digital circuit built in.

With the above structure, the analog section A and the digital section D are separated as much as possible.
Electrical separation layers I1 and I2 using a PN junction separation (the separation layer I2 has a shape surrounding the digital part D) are provided between the analog part A and the digital part D. Since the digital circuit is completely independent of the potential from the P-type substrate Sub, a path through which noise of the digital circuit is mixed into the analog circuit is cut off. As described above, when an analog circuit and a digital circuit are formed on one semiconductor substrate, noise of the digital circuit is mixed into the analog circuit, thereby deteriorating the operating characteristics of the analog circuit. Have been around.

[0025]

As described above, according to the semiconductor integrated circuit of the present invention, the analog circuit and the digital circuit are formed on one semiconductor substrate. The path through which the noise is mixed into the analog circuit is cut off, so that the operating characteristics of the analog circuit do not deteriorate.

Further, according to the semiconductor integrated circuit device of the present invention, the relationship between the operation timing of the analog circuit and the operation timing of the digital circuit due to external noise or the like does not change.
The possibility of malfunction can be reduced. In addition, it is not necessary to increase the number of control circuits, or increase the number of control ports of the control circuit, or perform a measure such as providing another control circuit according to the number of circuits that need to be controlled. The cost and the circuit area can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an audio device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration in a case where the number of circuits that need to be controlled is large in the audio device according to the embodiment of the present invention;

FIG. 3A is a top view of a semiconductor integrated circuit according to an embodiment of the present invention; (B) It is a sectional view of a semiconductor integrated circuit which is one embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of an example of a conventional semiconductor integrated circuit device.

FIG. 5 is a diagram showing that in a conventional semiconductor integrated circuit device, when the number of circuits that need to be controlled by a microcomputer increases, the device is more susceptible to external noise.

FIG. 6A is a diagram showing a configuration in which, in a conventional semiconductor integrated circuit device, a number of control ports are increased and one microcomputer controls many circuits. (B) In a conventional semiconductor integrated circuit device, a diagram showing a configuration in which many circuits are controlled by a plurality of microcomputers without increasing the number of control ports. (C) In a conventional semiconductor integrated circuit device, there is shown a configuration in which many circuits are controlled by one microcomputer with a control circuit interposed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control circuit 2 Audio circuit 3 Switch circuit 21 Surround circuit 22 Tone circuit 23 Volume circuit 24 Mute circuit 31, 32, 33 Transistor 100 Microcomputer 200 Audio IC 300 Load group 301 Power amplifier 302 Speaker 303 Capacitor 304 Lamp 305 Motor

Claims (2)

[Claims] 1. An analog circuit forming an analog circuit and a digital circuit forming a digital circuit are separated from each other as much as possible and separated from each other between the analog circuit and the digital circuit. A semiconductor integrated circuit, wherein an analog circuit and a digital circuit are formed on one semiconductor substrate after providing a separation layer for performing the operation. 2. A semiconductor integrated circuit device comprising: a plurality of circuits related to each other in operation content; and a control circuit controlling operation of the plurality of circuits based on a common control signal. In addition, the analog section which is an area where the analog circuit is formed in the control circuit and the digital section which is an area where the digital circuit is formed among the plurality of circuits and the control circuit are separated as much as possible. And a separation layer is provided between the analog section and the digital section to electrically separate the analog section and the digital section, and the plurality of circuits and the control circuit are mounted on a single semiconductor substrate. A semiconductor integrated circuit device characterized by being formed.