RF Energy Harvesting using Cross-couple Rectifier and DTMOS on SOTB with Phase Effect of Paired RF Inputs

Abstract

In this paper, the design and evaluations of a cross-couple rectifier (CCR) with floating sub-circuit using Dynamic Threshold MOSFET (DTMOS) for RF energy harvesting is presented. The circuit is fabricated using 65nm Silicon on Thin Buried Box (SOTB) CMOS technology. The measurement result shows that circuit exceeds 1000 mV DC output at -14 dBm input power and obtains 48 % power conversion efficiency (PCE) at a level of -10 dBm input power. The proposed circuit generated 0.9 μW DC output power at a level of -21 dBm input power which equivalent to 10.6 % PCE when harvesting the 950 MHz LTE signal in the ambient environment. The study also indicates the effect of phase difference between the two RF input signals on the DC output voltage in CMOS CCR. The DC output voltage depends on the phase of the two RF input signals and reaches a maximum when the phase difference between the two RF signals is π. Experimental results demonstrate that the output voltage changes from 950 mV to -100 mV when the phase difference varies from π to 0 at an RF input power of -10 dBm. When the rectifier receives an RF signal from the environment at an input power of -21 dBm, the DC output voltage changes from 300 mV to -50 mV when the phase changes from π to 0.