Compact low-cost five-band RF energy harvester using system-in-package integration

A compact five-band radio-frequency (RF) energy harvester (EH) using a system-in-package technique to take advantages of different technologies is proposed in this work. The RF EH is composed of five matching networks realized on a low-loss integrated-passive-devices (IPD) carrier and five rectifiers on a 0.18-μm CMOS chip. The CMOS chip is flipped and bonded to the IPD carrier through low-loss interconnects so that each on-chip rectifier can be integrated with an on-carrier matching network to support one of five band operations. High-g IPD passive components are employed to realize the matching networks. This not only provides a compact and low-cost solution, but the matching network can also give a high voltage gain to enhance the EH dc-to-RF conversion efficiency η. Native devices with a low threshold voltage provided by the 0.18-μm CMOS technology are chosen to improve the rectifier sensitivity. The proposed RF EH can give measured output voltages of 1.75, 1.77, 1.23, 1.19, and 1.26 V with n of 15.4, 15.7, 7.6, 7.1, and 8.0% at 0.74, 0.89, 1.8, 2.12, and 2.36 GHz, respectively, as the input RF power is −14 dBm and the load resistance is 500 kΩ. The proposed RF EH only occupies a 16.56 mm2 area.