An efficient wireless sensor node for autonomous sensing in the ISM band

Abstract

This paper presents a radio frequency powered wireless sensor node (WSN) implemented in 22-nm FD-SOI technology, designed for autonomous operation in the ISM band. The sensor node harvests energy from a dedicated 915 MHz radio frequency (RF) source and generates a 2.44 GHz carrier signal for data transmission. The proposed design integrates a high-efficiency RF rectifier utilizing ultra-low-power diode-based rectification and SOI MOSFET back-plate connections, enhancing energy conversion efficiency and sensitivity. A nanowatt-level power management unit (PMU) ensures stable operation with minimal power overhead. The wireless transmission module employs a DLL-based XOR frequency synthesizer with an improved duty cycle correction circuit, achieving low-power, high-precision RF carrier generation. Operating at an RF input power sensitivity as low as − 25 dBm, the WSN can function effectively up to 12 m from the power source. Experimental results demonstrate a peak power conversion efficiency (PCE) of 57% at − 14 dBm and 28% at − 25 dBm, with a maximum input tolerance of 0 dBm to prevent device breakdown. Using On–Off Keying (OOK) modulation, the transmitter outputs − 3.8 dBm power with 55% power efficiency via a switching power amplifier. The synthesizer and power amplifier consume 160 µW and 500 µW, respectively. Occupying a 0.17 mm² active die area, this design offers an area-efficient, sustainable, and cost-effective solution for diverse remote sensing applications.