Protection circuit provided in semiconductor circuit

Abstract

A protection circuit including a power supply terminal supplied with a power supply potential, a reference terminal supplied with a reference potential, and a first p-channel MOS transistor having a first gate, a first source, a first drain and a first back gate. The first gate, the first source and the first back gate are connected to the power supply terminal. Also included is a second p-channel MOS transistor having a second gate, a second source, a second drain and the first back gate, in which the second source of the second p-channel MOS transistor is connected to the first drain of the first p-channel MOS transistor, and the second gate and the second drain of the second p-channel MOS transistor is connected to the reference terminal. The circuit also includes a first n-channel MOS transistor having a third gate, a third source, a third drain and a second back gate, in which the third gate, in which the third source and the second back gate of the first n-channel MOS transistor are connected to the reference terminal, and including a second n-channel MOS transistor having a fourth gate, a fourth source, a fourth drain and the second back gate, in which the fourth source of the second n-channel MOS transistor are connected to the third drain of the first n-channel MOS transistor, and the fourth gate and the fourth drain of the second n-channel MOS transistor are connected to the power supply terminal.