Circuit device and electronic apparatus

a technology of circuit device and electronic device, which is applied in the direction of motor/generator/converter stopper, dynamo-electric converter control, pulse technique, etc., can solve the problem of fluctuation of the potential of the substrate, and achieve the effect of reducing the effect of the potential fluctuation of the substrate on the operation of the circui

US20140247001A1Inactive Publication Date: 2014-09-04SEIKO EPSON CORP
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2014-09-04
Estimated Expiration
Not applicable · inactive patent

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Abstract

An electronic circuit includes a noise source and an analog circuit and a logic circuit that may be adversely affected by noise. At least a portion of the analog circuit and the logic circuit is formed on a buried impurity layer whose conductivity is different from that of a substrate, and at least a portion of the periphery of that portion is surrounded by an impurity layer that is different from the substrate. Thus, propagation of the noise from the noise source is prevented.
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Description

BACKGROUND

[0001] 1. Technical Field

[0002] The present invention relates to a circuit device and an electronic apparatus or the like.

[0003] 2. Related Art

[0004] A technique of controlling the number of revolutions of a motor by controlling a chopping current is known as a technique for a motor driver that drives a DC motor. In this technique, a current flowing to a bridge circuit is converted to a voltage by a sense resistor, and the resultant voltage is compared with a reference voltage, to detect a chopping current. The detection result is fed back to a control circuit, to perform PWM control of a drive signal for the bridge circuit, thereby rotating a motor at a fixed rate.

[0005] For example, JP-A-2008-042975 discloses a technique of improving the precision of detection of the chopping current in such a motor driver. In this technique, a sense resistor is provided for each half bridge of an H-bridge, where one resistor detects that the current in the charge period has reached a predete...

Examples

Embodiment Construction

[0047]The following describes in detail a preferred embodiment of the invention. It should be noted that the embodiment to be described hereinafter is not intended to unduly limit the scope of the invention defined by the appended claims and that the entire configuration to be described in the embodiment is not necessarily essential as the means for achieving the invention.

[0048]1. Configuration of Substrate of Comparative Example

[0049]FIG. 1 shows the configuration of a substrate of a comparative example of this embodiment. FIG. 1 is a cross-sectional view of a substrate of an integrated circuit device constituting a circuit device.

[0050]It should be noted that although a case where the circuit device is a motor driver as described later with reference to FIG. 3, for example, will be described as an example below, this embodiment is not limited to this, but can be applied to various types of circuit devices that perform switching operation of a drive current or a drive voltage. For...