Field effect transistor with switchable body to source connection

Abstract

To avoid forward biasing the diodes within an N-channel transistor, the body and source of the N-channel transistor are switchably connected via a high-voltage FET. The gates of the N-channel transistor and high-voltage transistor are connected together so that both transistors are on or off simultaneously. When both transistors are on, the high-voltage transistor shorts the body and source of the N-channel transistor. When both transistors are off, the body and source of the N-channel transistor are disconnected and a third transistor couples the body to a reference potential. The N-channel transistor and high voltage transistor share a common body in a semiconductor substrate. The source of the N-channel transistor provides an output terminal for the circuit. A number of these devices, each connected to a different supply voltage, can be connected to the same output terminal and selectively energized to form a voltage multiplexer.