Abstract: A switch circuit includes first switches; and second switches. The first switches and the second switches are alternately arranged one by one, and a semiconductor substrate is of a first conductive type. Each of the first switches comprises a first transistor of a second conductive type which is opposite to that of the semiconductor substrate, and each of the second switches includes a second transistor of the second conductive type, surrounded by an outer well of the second conductive type.

Abstract: An image data signal processor, that includes a clamp circuit for clamping a DC level of an image data signal to a predetermined level to produce a clamped image data signal, an A/D converter for A/D-converting the clamped image data signal into a digital image data signal based on a lower reference voltage and an upper reference voltage, wherein the predetermined level is a minimum level of the A/D converter, and a reference voltage generating section for generating the lower and upper reference voltages from the digital image data signal to send to the A/D converter.