A 2.5-V, 160-μJ-output piezoelectric energy harvester and power management IC for batteryless wireless switch (BWS) applications

A piezoelectric-based energy harvesting and power management IC that can supply a total energy of 160-μJ at 2.5V from a single button-pressing action to realize a batteryless wireless remote switch (BWS) is presented. The IC uses a 6:1 series-parallel switched-capacitor converter and a bias-flipping inductor to match the impedance, down-convert the voltage, and maximize the total energy harvested from a 300-mm² PMN-PT disc. Also, a step-down buck regulator employs a variable on-time PFM control to keep the initial charging loss below 12-μJ without degrading load regulation at 2.5V. Using this IC fabricated in a 0.25-μm HV CMOS, a batteryless wireless switch that can successfully transmit a 4-byte-long message over a 10-m distance is demonstrated.