Patent ID: 7746152

Claim:
A switch circuit device comprising: a plurality of n-ch MOSFETs whose gates are connected together and whose drains and sources are connected in series; a p-ch MOSFET whose gate is connected to the gates of the plurality of n-ch MOSFETs and whose drain is connected to the source and drain connected to each other of at least one pair of adjacent n-ch MOSFETs of the plurality of n-ch MOSFETs; and a voltage changing circuit for applying a low voltage to the source of the p-ch MOSFET while a high-level control voltage is applied to the gate of the p-ch MOSFET, the low voltage being lower than the high-level control voltage, and a high voltage to the source of the p-ch MOSFET while a low-level control voltage is applied to the gate of the p-ch MOSFET, the high voltage being higher than the low-level control voltage.