Patent ID: 7636015

Claim:
A differential amplifier, comprising: first and second transistors each being a dual gate transistor and each having a first gate, a second gate, a source, and a drain open to a drain side, the first gate and the second gate being controlled independently each other, a differential input being supplied to between the first gate of the first transistor and the first gate of the second transistor, and the source of the first transistor and the source of the second transistor being connected in common to a first reference potential; first and second load circuits each connected to each of the drain side of the first transistor and the drain side of the second transistor; a detection circuit configured to detect a common-mode voltage between the drain side of the first transistor and the drain side of the second transistor; and a comparison and amplification circuit configured to amplify the common-mode voltage in comparison with a second reference potential and to supply an output signal thereof to both of the second gate of the first transistor and the second gate of the second transistor.