An energy-autonomous piezoelectric energy harvester interface circuit with 0.3V startup voltage

Abstract

A high efficiency energy-autonomous interface circuit for piezoelectric energy harvester is presented in this paper. The proposed circuit includes a negative voltage converter (NVC) with dynamic body bias control, a reconfigurable switching converter working in discontinuous conduction mode (DCM) and a clock generator. The body biasing circuit provides dynamic forward body bias control to enhance NVC conversion efficiency in low input voltage range and reduce substrate leakage under high input voltage range. A reconfigurable switching converter in DCM boost/buck-boost modes provides synthesized resistive input impedance for power matching and voltage step-up. Implemented in a standard 65nm CMOS process, the proposed system has a measured cold startup voltage of 0.3V with a maximum conversion efficiency of 70%.