Analog-to-digital converter and image sensor including the same

Abstract

Provided is an image sensor, which includes a pixel array including a plurality of active pixels, and an analog-to-digital converter (ADC) that converts a pixel signal of the plurality of active pixels into a digital signal. The ADC includes an input circuit outputs a first signal in which a ramp signal is applied to the pixel signal; an inverter including a pull-up transistor and a pull-down transistor connected in series between a power supply node and a ground node and that outputs a second signal obtained by inverting the first signal input through an input node to an output node; and a code generation circuit that outputs the digital signal based on the second signal. The inverter includes at least one bias transistor connected in series with the pull-down transistor between the pull-down transistor and the ground node and controlled by a bias voltage.