A Miniaturized, Power-Efficent Stimulator Output Stage Based on the Bridge Rectifier Circuit

Nerves can be artificially stimulated in people paralyzed after spinal cord injury to restore muscle function. The miniaturization of implantable stimulators is currently limited by the size of the large off-chip blocking capacitors that are used to ensure that no direct current flows between the electrodes in the event of a semiconductor failure. This paper proposes a new stimulator output stage circuit utilizing the principle of high-frequency current switching which allows the blocking capacitors to be integrated on-chip. The new design is based on the bridge rectifier circuit and achieves an increase of about 50% in power efficiency over a previous circuit. The approach has been verified by SPICE simulations in a 1mum SOI-CMOS technology