Ultra low readout noise architecture having a pixel sensor with dual active pixel sensor pixel and dual ramp line

Abstract

A method to read out pixels includes reading a first pixel by resetting a first photodetector, integrating the first photodetector after resetting the first photodetector, resetting a first floating diffusion node coupled to the first photodetector and a second floating diffusion node coupled to a second photodetector, transferring charge from the first photodetector to the first floating diffusion node, comparing a first signal at the first floating diffusion node and a second signal at the second floating diffusion node and generating a first signal to latch a first counter value when the first signal is less than the second signal, incrementing the first signal and decrementing the second signal, and comparing the first signal and the second signal and generating a second signal to latch a second counter value when the first signal is greater than the second signal, wherein the difference between the second counter value and the first counter value indicates a first pixel level.

Dependencies are inferred from the claim text.