Semiconductor device with transistors that convert a voltage difference into a drain current difference

Abstract

A semiconductor device is provided, which includes a pair of differential transistors that convert a voltage difference between a first input terminal and a second input terminal into a drain current difference between a first transistor and a second transistor and in which a voltage range of the first input terminal or the second input terminal is wide. A SOI structure MOSFET is used as each of the pair of differential transistors. The MOSFET includes a general MOSFET structure including a source region, a drain region, a well region between both the regions, a gate oxide film on an upper surface of the well region, and a gate electrode on the gate oxide film, and further includes a first conductivity type substrate region under the source region, the drain region and the well region through a buried oxide film. In the MOSFET, the first conductivity type substrate region of the first transistor is the first input terminal, and the first conductivity type substrate region of the second transistor is the first input terminal.