Patent ID: 7807955

Claim:
An image sensor comprising: a pixel array including a plurality of pixels with at least one pixel comprising a first transistor having a gate terminal adapted to receive a transfer signal disposed between a photosensitive element and a floating diffusion; a second transistor including a gate terminal connected to the floating diffusion, a first diffusion region connected to a pixel power line, and a second diffusion region connected to a pixel output line; and a third transistor including a gate terminal adapted to receive a reset signal disposed between the floating diffusion and the first diffusion region, wherein one or more pixels are connected to the second and third transistors and each photosensitive element, floating diffusion, first diffusion region, and second diffusion region are formed in a well of a first conductivity type; and sampling and readout circuitry associated with the pixel array; wherein in conjunction with readout of one or more pixels in a selected group of pixels of the pixel array, a pixel power line signal of the array transitions from an inactive state to an active state, and a reset signal of a non-selected group of pixels of the pixel array transitions from an active state to an inactive state within a predetermined time prior to the pixel power line signal transitioning from its inactive state to its active state, and wherein said image sensor is configured to satisfy a charge balance equation given by: C RG ΔV RG +C PP ΔV PP ≅0, where C RG is capacitance between the gate terminal of the third transistor and the well, C PP is capacitance between the pixel power line and the well, ΔV RG is a change in voltage level of the reset signal in said transition from its active state to its inactive state, and ΔV PP is a change in voltage level of the pixel power line signal in said transition from its inactive state to its active state.