Piezoelectric micro-power generation interface circuits

New power conversion circuits to interface to a piezoelectric micro-power generator have been fabricated and tested. Circuit designs and measurement results are presented for a half-wave synchronous rectifier with voltage doubler, a full-wave synchronous rectifier and a passive full-wave rectifier circuit connected to the piezoelectric micro-power generator. The measured power efficiency of the synchronous rectifier and voltage doubler circuit fabricated in a 0.35-mu m CMOS process is 88% and the output power exceeds 2.5 mu W with a 100-k Omega, 100-nF load. The two full-wave rectifiers (passive and synchronous) were fabricated in a 0.25-mu m CMOS process. The measured peak power efficiency for the passive full-wave rectifier circuit is 66% with a 220-k Omega load and supplies a peak output power of 16 mu W with a 68-k Omega load. Although the active full-wave synchronous rectifier requires quiescent current for operation, it has a higher peak efficiency of 86% with an 82-k Omega load, and also exhibits a higher peak power of 22 mu W with a 68-k Omega load which is 37% higher than the passive full-wave rectifier.