A Full-Wave Rectifier for Interfacing with Multi-Phase Piezoelectric Energy Harvesters

This paper describes an asynchronous full-wave rectifier for use with a multiple-electrode disk-shaped piezoelectric generator. By using quarter-circle shaped electrodes, similar to an ultrasonic motor, multiple output voltage phases are obtained from a single resonating piezoelectric disk. Two-electrode transducer outputs are often rectified using a full-wave diode bridge rectifier, which requires a significant voltage drop between input and output, decreasing the rectifier´s voltage efficiency. Previous asynchronous rectifiers use MOS switches to avoid the diode drop, however they lack the ability to efficiently rectify the multiple output phases generated from a disk-shaped transducer. Other CMOS rectifiers need two input waveforms that are equal and opposite, which a piezoelectric transducer may not generate for many input vibrations.