Characterization of an Ultra-Low-Power Start-Up Circuit for Highly Resistive Micro-Power Energy Harvesting Sources

To support the development of battery-less wireless sensor nodes (WSN), this paper presents the experimental characterization and silicon validation of an integrated Start-Up (SU) circuit for a Radio Frequency (RF) Energy-Harvesting (EH) micro-power management unit (μ PMU). Designed to satisfy the rigorous specifications of RF EH at distances of several meters from the source, the fabricated prototype extracts sufficient energy from highly resistive micropower sources to cold-start the μ PMU and targets maximum current delivery to the storage capacitor, thereby reducing charging times and supporting loads with higher current demands. The circuit is implemented in a STMicroelectronics 110-nm technology, and measurements show operation down to input voltages of 123 mV and available powers below 0.5μ W, achieving an output voltage higher than 1.2 V.