Bias voltage forming circuit, amplifying circuit, streamline type AD adaptor

Abstract

A first bias voltage generating circuit which applies a bias voltage to an amplifier circuit of an AD converter has a driving unit and a control unit. The driving unit includes a first bias circuit and a second bias circuit as a plurality of bias circuits which are connected in parallel and have different current driving capabilities. The first bias circuit and the second bias circuit each include a CMOS transistor which is connected directly between a power supply potential and a ground potential, and a switching element which interrupts a feedthrough current. The drains of the CMOS transistors output the bias voltage. The control unit turns on both or either one of the first bias circuit and the second bias circuit, thereby controlling the current driving capability of the entire driving unit.

Description

technical field

[0001] The invention relates to a bias voltage generating circuit and an amplifying circuit. In particular, the present invention relates to techniques for controlling bias circuits. Background technique

[0002] In recent years, mobile phones have been equipped with various additional functions such as image capture function, image playback function, video capture function, and video playback function, and there is a strong demand for reduction of power consumption of built-in amplifier circuits. In particular, single-chip LSIs incorporating analog-to-digital converters (hereinafter referred to as AD converters) have been miniaturized year by year, requiring a further reduction in power supply voltage. As an AD conversion circuit with high conversion accuracy, a multi-stage pipeline AD converter is known (for example, refer to Patent Document 1). Also, a technique is known in which an operational amplifier is incorporated in an AD converter, and an output ...

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