Enabling Higher-Voltage Operation of SOI CMOS Transistors

A “smart” back-gate driver circuit has been proposed to enable the operation, at voltages higher than were previously possible, of a silicon-on-insulator (SOI) complementary metal oxide/semiconductor (CMOS) integrated circuit that contains both low- and high-voltage transistors energized by corresponding low- and high-voltage power supplies. As used here, “low voltage” signifies potentials ≤3.3 V, while “high voltage” signifies potentials ≥40 V. The purpose of the back-gate driver circuit is to raise the threshold (turn-on) voltages of parasitic back-channel transistors (BCTs) that unavoidably exist in such an integrated circuit (see Figure 1). Turn-on of the parasitic transistors is unacceptable because it causes short circuits that render the integrated circuit inoperative.