An integrated switch in a HV-SOI wafer technology, with a novel self-protection mechanism

An integrated switch to control electrical stimuli in implantable medical devices is presented. First a self-biased protection mechanism to avoid V_GS reaching maximum rated value is presented. Then, using a HV-CMOS technology this technique is incorporated in a fully integrated switch, to control 0 to 16V, and 0 to 30 MA, pulses for implantable stimulators. Because of the low supply voltage V_DD between 2 to 5V, and safety considerations in implantable devices, special level shifters, drivers, and a voltage multiplier, that drive a large 40000μm/3μm dual-in-series PMOS switch, were necessary for the circuit. The circuit was fabricated in a HV 0.6μm CMOS technology in SOI wafer for transistor isolation, and tested. Measurement results that closely fit the expected performance of the circuit are presented.