An ultra-low power power management unit with −40dB switching-noise-suppression for a 3×3 thermoelectric generator array with 57% maximum end-to-end efficiency

A high efficiency, dynamically adaptable Power Management Unit (PMU) consuming less than 3μW, for an energy harvesting system based on a thermoelectric generator (TEG) array is presented. A boost converter with a cascaded low drop-out (LDO) voltage regulator comprises the proposed PMU. The design approach allows the PMU to reach maximum power transfer by matching the TEG´s dynamic series resistance and simultaneously provide adaptive switching noise rejection. The boost converter´s switching frequency (f_sw) is tracked via a background sense-and-control loop which modifies the LDO´s power supply rejection (PSR) characteristics to place a notch around the average f_sw. Overall system efficiency is better than 57%, and PSR of -40dB at f_sw are achieved. The total active area is 0.93 mm² in 0.5 μm CMOS.