A 100-nW sensitive RF-to-DC CMOS rectifier for energy harvesting applications

A 100-nW sensitive differential drive CMOS RF-DC converter implemented in a 0.18 mu m technology is developed. The circuit is meant to be used as a bootstrap or start-up circuit in an energy harvesting application. The 66-stage rectifier is tapered for optimal performance. Driving a 10 M Omega load, the circuit has a measured output greater than 100 mV, for an input power of 100 nW at 350 MHz. For an input power of 100 mu W at 350 MHz, the circuit is measured to have an output of 1.25 V, for an output load of 10 M Omega. Measurement results include balun and matching network losses. For infinite output resistive loads, the circuit is simulated to have an output greater than 1 V, for input powers larger than -30 dBm.