Patent ID: 7463282

Claim:
A solid-state image pickup device comprising: an image sensor outputting a black reference signal during at least one of a vertical blanking period and a horizontal blanking period; a correlated double sampling circuit for removing noises from an output signal from the image sensor and outputting a correlated output signal; a gain control amplifier for amplifying the correlated output signal of the correlated double sampling circuit and outputting a gain adjusted output signal; and a clamp circuit for making the output value of the gain control amplifier corresponding to the period of the black reference signal coincident with a predetermined reference value by controlling the gain control amplifier to vary the gain applied to the correlated output signal of the correlated double sampling circuit relative to a clamp signal provided to the gain control amplifier, wherein said clamp circuit comprises: a feedback loop for performing feedback control on said gain control amplifier on the basis of the gain adjusted output signal; operating means for comparing the gain adjusted output signal with a reference value and outputting a clamp signal; a switch for opening/closing said feedback loop in accordance with the period of the black reference signal; and gain control means for controlling the gain of the clamp signal supplied to said gain control amplifier.