Pixel circuit and method of operation thereof

Abstract

An embodiment circuit includes: a first source follower configured to be controlled by a voltage at a first node; a photodiode controllably coupled to the first node; and a bias transistor configured to be controlled by a bias voltage. The bias transistor has a first terminal coupled to the output of the first source follower. The circuit additionally includes: a storage node controllably coupled to the output of the first source follower; and an amplifier controllably coupled between the storage node and an output line. Also included in the circuit is a controllable switching element configured to couple the second terminal of the bias transistor to a supply voltage in response to the pixel operating in the first mode, and in response to the pixel operating in the A second mode couples the second terminal of the bias transistor to the output line.

Description

technical field [0001] The present disclosure relates generally to electronic circuits and, in particular embodiments, to a pixel circuit and method of operation thereof. Background technique [0002] Image sensors using photodiode pixels can be implemented in a complementary metal oxide semiconductor (CMOS) architecture. Each photodiode pixel of a CMOS image sensor may include an image sensitive element and associated image processing circuitry may be implemented in a single chip. Each photodiode pixel may also include a plurality of capacitors and at least one source follower, which may act as an amplifier. Such photodiode pixels can exhibit high power consumption due to the use of capacitors and generate kTC noise associated with capacitors and random telegraph signal (RTS) noise associated with source followers. As such, photodiode pixels of CMOS image sensors are ineffective for certain applications or environments (eg, low light conditions) where at least one of a lo...

AI Technical Summary

Problems solved by technology

Such photodiode pixels can exhibit high power consumption due to the use of capacitors and generate kTC noise associated with capacitors and random telegraph signal (RTS) noise associated with source followers

As such, photodiode pixels of CMOS image sensors are ineffective for certain applications or environments where at least one of a low power mode of operation or a low noise floor is desired (e.g., low light conditions)

Images