High-sensitivity and high-efficiency 2.4-GHz RF energy harvester using SiP technique

A high-efficiency and compact RF energy harvester (EH) using a system-in-package (SiP) technique is proposed in this work. The EH is consisted of an input matching network, an interconnect, and a rectifier. The rectifier implemented in 0.18-μm CMOS technology is co-designed with the input matching network to provide high RF-to-dc conversion efficiency. High-Q passive components in integrated-passive-device (IPD) process are employed to realize the input matching network which can provide high impedance transformation ratio to boost the input voltage swing to the rectifier. Hence the EH sensitivity can be greatly improved. The rectifier and the IPD matching network is then integrated together by the low-loss interconnect using the SiP technique. The measurement results show that the proposed RF EH can provide peak efficiency of 3.7 % at 2.4 GHz as the output dc voltage and the load resistance are 1 V and 500 kΩ, respectively, around 68 % improvement as compared with a RF EH using an on-chip matching network. Clearly the SiP technique is very suitable for enhancing the RF EH efficiency.