Patent ID: 8097904

Claim:
An active pixel image sensor (APS) configured to sense a photon received by a pixel surface, the APS comprising: a first integrated circuit (IC) layer having a first back surface coupled to the pixel surface for receiving the photon, a first front surface having a first plate, and an analog device formed between the first back and front surfaces, the analog device coupled to the pixel surface and the first plate; a second IC layer formed underneath the first IC layer, the second IC layer having second front and back surfaces and a digital device formed between the second front and back surfaces, the second front surface having a second plate configured to be capacitively coupled to the first plate of the first IC layer, the digital device coupled to the second plate of the second front surface; and a passivation oxide layer coupled between the first and second plates, wherein the first and second plates and the passivation oxide layer form a capacitor between the first and second IC layers.