Patent ID: 7488927

Claim:
A semiconductor integrated circuit device comprising: a correlated dual sampling circuit for sampling and holding a signal corresponding to a black level of a feedthrough part of a pixel signal generated by an image sensor device and generating an output signal corresponding to a differential signal between the sampled and held black level and a signal part of the pixel signal; a variable gain amplifier circuit for amplifying the output signal of the correlated dual sampling circuit; an A/D converter circuit for receiving an amplified signal from the variable gain amplifier circuit; and a D/A converter circuit for converting a received feedback signal formed with an output signal of the A/D converter circuit and a clamp signal into an analog signal and providing the analog signal as feedback to the variable gain amplifier circuit or the correlated dual sampling circuit, wherein the D/A converter circuit includes a plurality of first-conductivity-type MOSFETs as first current sources for feeding respective currents having binary weights corresponding to multiple-bit digital signals, a plurality of first-conductivity-type first differential MOSFETs which receive the multiple-bit digital signals respectively, a plurality of second-conductivity-type second differential MOSFETs in which gates and drains of the second differential MOSFETs are connected to gates and drains of the first differential MOSFETs respectively, a plurality of second-conductivity-type MOSFETs as second current sources for feeding respective currents having binary weights corresponding to the multiple-bit digital signals, the MOSFETs as second current sources being provided at source sides of the second differential MOSFETs, a differential amplifier circuit in which a predetermined bias voltage is supplied to a noninverting input terminal of the differential amplifier circuit and an inverting input terminal of the differential amplifier circuit is connected to an analog current output node to which the drains are connected on one of the sides of the first differential MOSFETs, and a resistive element which is provided between the inverting input terminal and an output terminal of the differential amplifier circuit, and the differential amplifier circuit generates a converted analog output voltage at the output terminal.