Column amplifier to support dual conversion gain and dual analog gain readout

An imaging system, comprising:

• a pixel array including a plurality of pixel circuits arranged in rows and columns, wherein each pixel circuit is configured to generate image signals in response to incident light;
• a column amplifier coupled to the pixel array, wherein the column amplifier comprises:
• an input node coupled to receive image signals from one or more of the pixel circuits;
• an output node;
• and
• an input stage coupled between the input node and the output node, wherein the input stage comprises:
• a capacitor array including a first capacitor coupled to the input node, a floating voltage node coupled to the first capacitor, and a second capacitor coupled between the floating voltage node and the output node;
• a reset switch coupled between the floating voltage node and the output node;
• and
• a transistor having a gate terminal coupled to the floating voltage node, and coupled between the output node and ground;
• and
• a comparator having a first input coupled to the output node of the column amplifier and a second input coupled to receive a ramp signal.