Patent ID: 7355445

Claim:
A semiconductor device comprising: a first transistor; a second transistor; a third transistor; and a fourth transistor, wherein: a gate terminal of the first transistor and a gate terminal of the second transistor are electrically connected; a drain terminal of the first transistor is electrically connected to a drain terminal of the second transistor; the drain terminal of the first transistor is electrically connected to a gate terminal of the third transistor; a drain terminal of the fourth transistor is electrically connected to a drain terminal of the third transistor; the gate terminal of the first transistor is supplied with one of a first signal potential and a second signal potential; a source terminal of the first transistor is supplied with a first power source potential; a source terminal of the second transistor is supplied with a potential equal to the first signal potential; a source terminal of the third transistor is supplied with a second power source potential; a source terminal of the fourth transistor is supplied with a third power source potential; the second signal potential is between the first power source potential and the first signal potential; the first power source potential is equal to the second power source potential; the third power source potential is higher than the first signal potential; the first transistor and the third transistor are n-channel type transistors; and the second transistor and the fourth transistor are p-channel type transistors.