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Differential binary pixel technology is a threshold-based timing, readout, and image reconstruction method that utilizes the subframe partial charge transfer technique in a standard four-transistor (4T) pixel CMOS image sensor to achieve a high dynamic range video with stop motion. This technology improves low light signal-to-noise ratio (SNR) by up to 21 dB. The method is verified in silicon using a Taiwan Semiconductor Manufacturing Company’s 65 nm 1.1 μm pixel technology 1 megapixel test chip array and is compared with a traditional 4 × oversampling technique using full charge transfer to show low light SNR superiority of the presented technology.

We describe a photon statistics-based theoretical model of the response to incident light of an image sensor and show that conditional reset and multibit temporal oversampling increase the dynamic range signifi- cantly. This photon-based modeling approach describes the full image sensor design space of temporal and spatial oversampling either with a binary comparison or with a multibit read of each sample. We find excellent quantitative agreement between measurements on custom hardware and our theoretical predictions. We then use this model to show what improvements in dynamic range and low-light response can be achieved by over- sampling and what the limits of improvement caused by pixel size and lens parameters are. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.JEI.23.1.013021)