A composite high-voltage device using low-voltage SOI MOSFETs

A circuit is described that uses low-voltage transistors to form a high-voltage composite device. The circuit is a series string of SOI (silicon-on-insulator) MOSFETs and associated biasing elements fabricated using a modified nMOS process on a SIMOX (separation by implantation of oxygen) substrate. The circuit voltages higher than the breakdown voltage of a single transistor by dividing the applied voltage among the transistors in the string. MOSFET-like characteristics with breakdown voltage up to 60 V are demonstrated using a string of 25 SOI MOSFETs, each with a breakdown voltage of 6-7 V