Patent ID: 9344658
Filing Date: 2016-05-17
CPC Classification: H01L,H04N

Claim Text:
1. A pixel cell, comprising: a photodiode disposed within a first substrate of a first semiconductor chip for accumulating an image charge in response to light incident upon the photodiode; a transfer transistor disposed within the first substrate of the first semiconductor chip and coupled to the photodiode to transfer the image charge from the photodiode; a bias voltage generation circuit disposed within a second semiconductor chip for generating a bias voltage, wherein the bias voltage generation circuit is coupled to the first substrate of the first semiconductor chip to bias the photodiode with the bias voltage, wherein the bias voltage is a negative voltage with respect to a ground voltage of a second substrate of the second semiconductor chip; and a floating diffusion disposed within the second substrate of the second semiconductor chip such that the first substrate in which the photodiode is disposed is biased at the negative voltage with respect to the ground voltage of the second substrate in which the floating diffusion is disposed, wherein the transfer transistor is coupled to transfer the image charge from the photodiode on the first semiconductor chip to the floating diffusion on the second semiconductor chip.