A CMOS INTEGRATED INTERFACE FOR PIEZOELECTRIC GENERATORS

This paper presents a low-voltage, low-power CMOS integrated interface circuit capable of optimizing the power transfer from a piezoelectric generator (PZT) into a rechargeable battery or a large capacitor. The circuit operates with PZT voltage amplitudes from 2.4 V to 7 V and input frequencies from 50 Hz to 1000 Hz. It has been designed for a supply voltage of 2 V, but the circuit keeps operable down to 1.2 V. The switching clock is derived from the PZT frequency, resulting in low switching losses. Simulation suggests conversion efficiencies up to 80% with a total power consumption of about 1.3 µW.