Patent ID: 8054358

Claim:
A solid-state image pickup device comprising: a plurality of pixels (PX) integrated in an array configuration on a semiconductor substrate; each pixel having a photodiode (PD) receiving light and generating and storing photoelectric charge, said photodiode (PD) having a first terminal and a second terminal connected to ground, a transfer transistor (Tr 1 ) having a source-drain path with a first terminal and a second terminal connected to said first terminal of said photodiode (PD) and a gate, a floating diffusion (FD) having a first terminal connected to said first terminal of said source-drain path of said transfer transistor (Tr 1 ) and a second terminal connected to ground, an amplification transistor (Tr 4 ) having a gate connected to first terminal of said floating diffusion and a source-drain path having a first terminal and a second terminal connected to a pixel output line, a first current source (I 1 ) conducting a first current from said pixel output line and ground; a compensating circuit has an amplifier having the output of said amplification transistor as input, and a compensating transistor having a gate electrode with the output of said amplifier connected to it; and the compensating circuit has negative feedback of the output of said compensating transistor to said amplifier, a second current source (I 1 ) conducting a second current from said compensating circuit output and ground; wherein said amplification transistor (Tr 4 ) having substantially the same ratio of gate width to gate length as and said compensating transistor (M 2 ); and wherein first current of said first current source (Ii) for said amplification transistor (Tr 4 ) substantially the same current as said second current of said second current source (I 2 ) for said compensating transistor (M 2 ).