An Ultra-Low-Power Power Management Circuit with Output Bootstrapping and Reverse Leakage Reduction Function for RF Energy Harvesting

The reverse leakage current in the rectifier is a key challenge in the design of RF energy harvesting (RF-EH) systems, especially in harvesting modulated RF signals from WLAN band. In this paper, we propose a dual-band energy harvesting system operating at GSM-900 (900 MHz) and WLAN (2.4 GHz) bands. To harvest the RF energy from the WLAN band more efficiently, an event-triggered 1:2 parallel-series switched-capacitor (SC) converter is proposed to reduce the reverse leakage current. Meanwhile, this SC converter can provide an output voltage bootstrapping function while maintaining an ultra-low-power consumption down to 28 nW by asynchronous control. The power management unit (PMU) with the rectifier is fully integrated in a CMOS 130-nm process. Measurement results have shown the PMU can boost up the output voltage by 1.73× with an input voltage as low as 0.2 V. When harvesting the modulated waveform, the RF-EH system output ripple is decreased by 6×, and reverse leakage current reduction is over 2500× compared to the direct connection condition.