Analysis and Optimization of Sense-and-Set Piezoelectric Energy Harvesting Interface Circuits

This article presents the modeling and optimization of a sense-and-set (SaS) rectifier. The basic equations governing the operation of a SaS rectifier are derived analytically using Laplace-transform techniques. An expression for the harvesting efficiency of a SaS rectifier is developed by evaluating the conduction and gate-drive losses as well as the output power of the rectifier. The derived expressions are then employed to locate the optimal design point of a SaS interface circuit. The proposed modeling approach reduces the required run time by more than 2000 times as compared to SPICE simulation without sacrificing accuracy. The following design parameters are determined for maximum efficiency: optimal relative size between the rectifier switches, total conductance of the rectifier, and sensing frequency. The close match between the theoretical expressions and circuit simulation results validates the proposed analysis.