A piezoelectric energy harvester interface circuit with adaptive conjugate impedance matching, self-startup and 71% broader bandwidth

This paper presents a piezoelectric energy harvesting interface circuit with a technique to broaden the bandwidth by introducing two time delays into the conventional synchronous-electrical-charge-extraction (SECE) scheme. The circuit adaptively adjusts these time delays for maximum power output at off-resonant frequencies. The bandwidth is increased by 71% while the power consumption of the circuit itself is at a low level of 0.85μW. The chip is fabricated in 0.35μm CMOS process technology.