Temperature-Stable Low-Power RF-to-DC Dickson Charge Pump Rectifiers for Battery-Free Sensing and IoT Systems

Temperature variation poses a significant challenge for battery-free sensors and Internet of Things (IoT) systems, mainly due to the absence of built-in temperature compensation modules. This work presents a strategy to identify Schottky diodes for low-power RF-to-dc Dickson charge pump (DCP) rectifiers to enhance temperature stability. Theoretical analysis pinpoints that performance degradation in dynamic temperatures results from the mismatch loss between diode nonlinear junction resistance and load resistance. The analytical method is implemented to synthesize the optimum number of stages and identify suitable Schottky diodes for low-power RF-to-dc DCP rectifiers. Experimental measurements demonstrate that the SMS7621-based 3-stage RF-to-dc DCP rectifier maintains a wide matched operating temperature range from $- 32.5~^{\circ }$ C to $70~^{\circ }$ C. Further experiments show that its dc output voltage remains above 3.2 V across a wide temperature range of $- 40~^{\circ }$ C to $80~^{\circ }$ C when the RF input is −8 dBm, which can drive a commercial wireless sensor board. This work aims to serve as a benchmark for developing reliable low-power RF-to-dc DCP rectifiers that meet various operating temperature requirements of battery-free IoT sensors.