In-pixel high dynamic range imaging

摘要

Embodiments of the invention describe providing high dynamic range imaging (HDRI or simply HDR) to an imaging pixel by coupling a floating diffusion node of the imaging pixel to a plurality of metal-oxide semiconductor (MOS) capacitance regions. It is understood that a MOS capacitance region only turns "on" (i.e., changes the overall capacitance of the floating diffusion node) when the voltage at the floating diffusion node (or a voltage difference between a gate node and the floating diffusion node) is greater than its threshold voltage; before the MOS capacitance region is "on" it does not contribute to the overall capacitance or conversion gain of the floating diffusion node. Each of the MOS capacitance regions will have different threshold voltages, thereby turning "on" at different illumination conditions. This increases the dynamic range of the imaging pixel, thereby providing HDR for the host imaging system.