IMAGE SENSOR PIXELS HAVING BUILT-IN VARIABLE GAIN FEEDBACK AMPLIFIER CIRCUITRY

摘要

An image sensor may include an array of image sensor pixels. Each pixel may have a photodiode, a floating diffusion node, and charge transfer gate. An amplifying transistor may have a gate terminal coupled to the floating diffusion and a drain terminal coupled to an output node. The amplifying transistor may provide signal corresponding to transferred charge with a greater than unity voltage gain. A negative voltage feedback capacitor having variable capacitance may be coupled between the output node and the floating diffusion node thereby increasing the pixel dynamic range. A reset transistor may be coupled between the floating diffusion and output node. The amplifying transistor may include a p-channel transistor formed within a mini n-well region of the pixel or an n-channel transistor formed within a mini p-well region. The pixel may have increased storage capacity and dynamic range relative to conventional designs.

主权项

1. An image sensor pixel, comprising:
a photodiode that generates charge in response to image light; a floating diffusion node; a charge transfer transistor configured to transfer the generated charge from the photodiode to the floating diffusion node; an amplifying transistor having a gate terminal coupled to the floating diffusion node and a drain terminal coupled to a pixel output node; and a feedback capacitor coupled between the pixel output node and the floating diffusion node, wherein the amplifying transistor is configured to provide the transferred charge with a greater than unity gain and the feedback capacitor is configured to provide negative voltage feedback to the floating diffusion node.