A Reconfigurable RF-to-DC Converter using an Adaptive Control Loop for a Passive Wake-up Receiver

Abstract

In this paper, a new reconfigurable RF-DC converter structure with an adaptive control loop is proposed for the efficient implementation of passive-type wake-up receivers, which are essential for wireless sensor networks using IoT devices. The proposed reconfigurable RF-to-DC rectifier structure automatically determines the number of rectifier units used for power conversion based on the output DC voltage obtained from the input RF power signal. Thus, high power-conversion efficiency is always maintained regardless of the input RF power level. In addition, a 4-bit switched capacitor bank is used to adjust the impedance matching network required for RF rectifiers. It is automatically configured by the proposed adaptive control loop according to the input RF power. The rectifier was implemented using a 0.25-μm CMOS process. The DC output voltage was obtained with a 100-kΩ load resistor and 915-MHz RF input frequency. When this output voltage is more than 0.5 V, the performance of the converter has a very wide power range of RF input of more than 25 dB (from -22 dBm to 5 dBm). It also has a power conversion efficiency above 30%.