There is provided a method of driving an image sensor which can remove FPN
resulting from inter-chip variations without requiring any dark correction. A semiconductor
photosensor chip has a plurality of sensor modules mounted on a mounting substrate,
and a semiconductor device in which at least an N signal input buffer circuit for
receiving N signals, an S signal input buffer circuit for receiving S signals,
a differential circuit for calculating any difference between the outputs from
the N and S signal input buffer circuits, and a voltage clamping circuit for clamping
the output from the differential circuit are formed on a single semiconductor substrate,
and the voltage clamping circuit clamps the reset state of S and N signal common
output line.