Comparator, analog-to-digital convertor, solid-state imaging device, camera system, and electronic apparatus

摘要

A comparator includes a first amplifier, a second amplifier, and a level holding part. The first amplifier includes differential-pair transistors and outputs a signal of a level corresponding to a comparison result from a first output node. The differential-pair transistors compare a reference voltage with a potential of an input signal. The second amplifier gain up the signal output from the first output node of the first amplifier and outputs the signal from a second output node. The level holding part holds a level of the second output node at a predetermined level. The second amplifier includes a transistor for amplification and a transistor for a current source. The level holding part holds the level of the second output node of the second amplifier such that the transistor for the current source does not fall into a level at which a saturated operation condition is not satisfied.

主权项

1. A comparator, comprising:
a first amplifier including differential-pair transistors and configured to output a signal of a level corresponding to a comparison result from a first output node,
the differential-pair transistors serving as a comparison part configured to compare a reference voltage with a potential of an input signal; a second amplifier configured to gain up the signal output from the first output node of the first amplifier and output the signal from a second output node; and a level holding part configured to hold a level of the second output node at a predetermined level,
the second amplifier includinga transistor for amplification connected between the second output node and a power supply or a reference potential source anda transistor for a current source connected between the second output node and the reference potential source or the power supply,the level holding part holding the level of the second output node of the second amplifier such that the transistor for the current source of the second amplifier does not fall into a level at which a saturated operation condition is not satisfied.