Pinned Photodiode Imaging Pixel With Floating Gate Readout and Dual Gain

We present an imaging pixel featuring dual conversion gain in a single exposure based on the pinned photodiode (PPD). The signal charge is first converted to voltage nondestructively using a floating gate, and a second conversion is done at a p-n junction-based sense node (SN). Higher signal dynamic range (DR) is achieved due to the sensing of the same charge with two different conversion gains. The results from a prototype 10- $\mu \text{m}$ -pitch pixel manufactured in a 180-nm CMOS image sensor process demonstrate a gain ratio of 3, DR of 90 dB, 3.6 e− rms readout noise, and negligible image lag.