Increasing pixel conversion gain in CMOS image sensors

A CMOS active pixel sensor, comprising:

• a photodiode arranged to receive light and convert said received light into charge;
• first and second transistors configured in a cascoded configuration, said first transistor allowing accumulation of charge in said photodiode, and said second transistor allowing transfer of accumulated charge from said photodiode to a feedback capacitor, said first and second transistors operating to convert said charge into electronic signal;
• and
• the feedback capacitor disposed between said photodiode and an input of said second transistor.

An image sensor, comprising:

• an array of pixel sensors, each sensor having
• a photo-sensor configured to receive photons and to convert said photons into charge,
• an output amplifier having at least two transistors in a cascoded configuration, said amplifier operating to convert said charge into electronic signal, and
• a feedback capacitor disposed between said photo-sensor and an input of said output amplifier;
• and
• a controller configured to provides timing and control signals to enable read out of signals stored in each pixel sensor.