Powering wearable sensors with a low-power CMOS piezoelectric energy harvesting circuit

Piezoelectric vibration based energy harvesters have been widely researched as powering modules for various types of sensor systems due to their ease of integration and high energy density. A number of piezoelectric transducer based topologies have been reported in literature. In this paper a piezoelectric transducer in parallel with a switch along with a low-power CMOS full-bridge rectifier is presented as a solution for efficient energy harvesting system for potential application in medical electronics. It consists of two NMOS and two PMOS devices comprising a full-bridge rectifier coupled with a PMOS device driven by a comparator based switch control circuit. With a load of 45KΩ, the output rectifier and the input piezoelectric transducer voltages are 694mV and 703mV, respectably, while the VOUT versus VIN conversion ratio is 98.7% with a power efficiency of 46%. The proposed energy harvesting circuit has been designed using a 0.13µm standard CMOS process.