Highly-Efficient CMOS Rectifier for Wide Range of Input RF Power in Energy-Harvesting Systems

We propose a CMOS rectifier with improved power conversion efficiency (PCE) at both low and high RF power, and enhanced dynamic range (DR). The proposed design utilizes 1) the additional boosting circuit to increase the overdrive voltage of transistors, which help achieve higher forward current and higher PCE at low RF power and 2) self-biasing technique implemented by additional diodes and capacitors, which control biasing voltage of transistors for higher PCE and reduced reverse leakage current at high RF power. The proposed rectifier shows about 13.8% and 9.1% higher PCE than that of conventional differential cross-coupled rectifier at low (-34.5 dBm) and high (-10 dBm) RF power respectively. Moreover, it offers improved DR (9.6 dB) and higher sensitivity of -16.9 dBm (the required input power for the output reaching 117) with slightly degraded peak PCE (76.7% at -24.1 dBm) in comparison with the conventional rectifier at 900 MHz frequency under a 100 k Omega load resistor. The proposed RF-to-DC converter was designed using 0.18 tm standard CMOS technology and the chip area is 149 mu m x 78 mu m without pads.