Patent ID: 8045305

Claim:
A protection circuit including: a first transistor which is an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) wherein one terminal of a conduction channel, a gate, and a back gate thereof is connected to a terminal to be protected; and a second transistor which is an N-channel MOSFET wherein one terminal of a conduction channel, a gate, and a back gate thereof is connected to a fixed voltage terminal, and the other terminal of the conduction channel thereof is connected to the other terminal of the conduction channel of the first transistor, wherein the first and second transistors are floating MOSFETs formed in a common N-type well formed in a P-type semiconductor substrate, and are provided in the form of separate devices, and wherein a common connection node which connects the first and second transistors is connected to the N-type well.