A Reconfigurable Passive RF-to-DC Converter for Wireless IoT Applications

In this brief, we present a reconfigurable rectifier, which makes it feasible to harvest energy with net-zero energy consumption, i.e., without draining power from battery, in a wide input power range. The proposed topology can operate with low input power signals and can be fine-tuned for a specific operating frequency in a wide frequency range from several MHz to GHz in remotely powered systems. A prototype is fabricated in 0.35- $ {\mu }\text{m}$ standard CMOS process and occupies 0.019 mm2. Although the proposed rectifier supports four different rectifier topologies, on silicon it only occupies the footprint of a single rectifier. At 13.56 MHz with 2.2 mW input power, the four-switch rectifier topology yields 82% power conversion efficiency (PCE), while the hybrid topology (diodes + switches) provides 81% PCE at 11.2 mW input power. The rectifier operates with input power as low as 1.1 mW, at which level the PCE is still reasonable at 65.2%. This allows a wireless device at low power level to operate at extended read range. This reconfigurable rectifier is especially suitable for Internet of Things mobile application, where the power of the incoming signal changes by the distance between the power source and the device.