Imaging sensor with amplifier having variable bias and increased output signal range

An image sensing system, comprising:

• a pixel array having a plurality of pixel circuits arranged into a plurality of rows and a plurality of columns, wherein each one of the pixel circuits includes:
• a photodiode coupled to photogenerate image charge in response to incident light;
• a transfer transistor coupled to the photodiode;
• a floating diffusion coupled to the transfer transistor, wherein the transfer transistor is coupled to transfer the image charge from the photodiode to the floating diffusion;
• an amplifier circuit having an input coupled to the floating diffusion, an output terminal coupled to generate an image data signal of the pixel circuit, and a variable bias terminal coupled to receive a variable bias signal;
• a reset switch coupled between the output and input terminals of the amplifier circuit to reset the amplifier circuit in response to a reset signal;
• and
• a variable bias generator circuit coupled to receive the reset signal to generate the variable bias signal in response to the reset signal, wherein the variable bias generator circuit is coupled to transition the variable bias signal from a first bias signal value to a second bias signal value in response to a transition of the reset signal from an active state to an inactive state;
• control circuitry coupled to the pixel array to control operation of the pixel array;
• and
• read out circuitry coupled to the pixel array to read out the image data signal from each one of the plurality of pixel circuits.