A voltage doubling passive rectifier/regulator circuit for biomedical implants

A circuit called prectulator is proposed in this paper. It utilizes the output transistor (Mpr) of a linear regulator also as a passive rectifier for providing a regulated DC output from an AC input. The bulk voltage and the gate voltage (Vg) of Mpr are biased by an auxiliary rectifier and an error amplifier (Ae), respectively. During startup and overload situations, overdriving Mpr may occur and is prevented by limiting Vg inside Ae. Using this technique, a voltage doubling prectulator was implemented in a 0.18μm CMOS process. At 15MHz with a peak AC voltage of 3.6V, a power efficient of 87.7% and a voltage conversion ratio of 1.67 were achieved for a 6V output with a load power of 46.8mW.