Diode Selection Strategies of RF Power Harvester to Improve Temperature Resilience of Battery-free Wireless Sensing

Temperature changes may lead to performance degradation or operation interruption in practical wireless sensing applications. Thus, the capability of an RF power harvester to provide stable and reliable dc output under temperature changes is critical for the proper operation of battery-free wireless sensing. This work presents a system analysis of a multi-stage RF power harvester considering a voltage comparator for wireless sensing as its load. Both theoretical and measurement results reveal that a Schottky diode with a higher nonlinear junction resistance is preferred, as it reduces mismatch loss and allows more harvested dc power to be delivered to its load. This work shows that the SMS7621 diode-based 3-stage harvester can provide stable 3.3-V dc output over a wide temperature range of −40 ºC to 80 ºC, which can significantly improve the temperature resilience of battery-free wireless sensing.