A voltage doubling passive rectifier/regulator circuit for biomedical implants

Abstract

A circuit called prectulator is proposed in this paper. It utilizes the output transistor (M_pr) 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 (V_g) of M_pr are biased by an auxiliary rectifier and an error amplifier (A_e), respectively. During startup and overload situations, overdriving M_pr may occur and is prevented by limiting V_g inside A_e. 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.