Efficient Dual-band Ultra-Low-Power RF Energy Harvesting Front-End for Wearable Devices

This paper presents a novel dual-band ultra-low power RF energy harvesting front-end for wearable devices, wireless sensor networks, and the Internet of things (IoT) designed in standard 130 nm CMOS technology. The proposed dual-band RF energy harvester operates at ISM bands of 915 MHz and 1.85 GHz and uses an efficient summation network to combine power from different frequency bands. A dual-band antenna receives signals from two different bands which are boosted by two different matching networks. Then, two self-compensated cross-coupled rectifiers convert the RF signals provided by the two different bands into DC output voltages. At the output of the two rectifiers, a summation network using switches and a control circuit combines power from different bands, charging the output capacitor. The post-layout simulation results demonstrate a sensitivity of -33 dBm for 1 V output at a capacitive load and the peak end-to-end efficiency is 43.2% at -18 dBm when two frequency bands are available. When only 915 MHz or 1.85 GHz is available, the results demonstrate a high peak efficiency of 42.3% and 44% at -16 dBm and -17 dBm, respectively..