In-pixel high dynamic range imaging system and imaging sensor pixels

Abstract

The application relates to an in-pixel high dynamic range imaging system and imaging sensor pixels. 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.

Description

technical field [0001] Embodiments of the invention relate generally to image capture devices, and more particularly, but not exclusively, to enhancing the dynamic range of image capture devices. Background technique [0002] The image capture device includes an image sensor and an imaging lens. The imaging lens focuses light onto the image sensor to form an image, and the image sensor converts the light into an electrical signal. Electrical signals are output from the image capture device to other components of the main electronic system. The electronic system may be, for example, a mobile phone, computer, digital camera, or medical device. [0003] As the pixel unit becomes smaller, it becomes more difficult for the pixel unit to output a signal of sufficient strength that can be easily deciphered by downstream signal processing. Furthermore, there is a need for image sensors to perform over a large range of lighting conditions varying from low light conditions to brigh...

AI Technical Summary

Problems solved by technology

This will lead to saturation of the floating diffusion node, resulting in reduced dynamic range and reduced signal-to-noise ratio (SNR)

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