Semiconductor device and power circuit including a sense transistor for current sensing

Abstract

A semiconductor device comprises a power transistor and a sense transistor. The power transistor conducts a power transistor current. The sense transistor conducts a sense transistor current substantially proportional to of the power transistor current. The power transistor and the sense transistor have drain source and a gate terminals, of which those of the sense transistor are arranged to be biased to those of the power transistor, respectively. The power transistor and the sense transistor each comprise: an inner region of type P−; an N-type buried layer; an N-type isolating barrier surrounding the inner region partially; an N-type source region in the inner region; an N-type drain region in the inner region. A barrier-to-drain connector connects the isolating barrier to the drain region, the one of the sense transistor has an electrical resistance which is higher than the resistance of the barrier-to-drain connector of the power transistor.