A 915 – MHz Differential Rectifier and ASK/OOK Demodulator SoC for RF Energy Harvesting in Battery-Less ESL and IoT Applications

This article presents the design and implementation of a novel receiver system-on-chip (SoC) for an RF energy harvester, which integrates a differential rectifier and a differential ASK/OOK demodulator. The SoC is fabricated using a standard 180 nm CMOS process. Targeted for applications in electronic shelf labels (ESL) and the Internet of Things (IoT), the proposed design operates in the 915 MHz ISM band. An off-chip differential matching network passively enhances the weak RF input signal from the antenna. A limiter circuit is incorporated within the proposed self-compensated differential rectifier to convert the RF signal into dual DC output voltages. The sixstage rectifier enhances the transistor overdrive voltage through dynamic negative biasing a. Furthermore, a novel differential ASK/OOK demodulator provides high-sensitivity detection of RFID signals transmitted from the reader. Measurement results demonstrate a startup sensitivity of -28.48 dBm for a capacitive load at a 1 V DC output, outperforming previously reported designs. The peak end-to-end power conversion efficiency reaches 45.5% at an input power of -2.26 dBm, delivering a load current of $106 \mu$ A and an output voltage of 2.53 V.