DESIGN OF A DUAL-BAND RF ENERGY HARVESTER WITH INTEGRATED LOW-NOISE CMOS RING VCO

Abstract

The growing need for energy-autonomous wireless systems has driven interest in ambient RF energy harvesting to power low-power communication and sensing devices. This work focuses on the simulation of a high-efficiency rectifier circuit designed in Keysight’s Advanced Design System (ADS), operating at 1.8 GHz with an input RF power of 0 dBm. Utilizing the HSMS-2850 Schottky diode and a lumped-element impedance matching network, the circuit achieves a DC output of 500 mV across a 5 kΩ load, with excellent return loss performance marked by S₁₁ = –21 dB. This effective RF-to-DC conversion is essential for ensuring maximum power transfer and supports sustainable operation in energy-constrained environments. To enable frequency generation and signal processing within the same power-limited framework, the design is extended to include a low-noise CMOS ring-type voltage-controlled oscillator (VCO). This VCO is compact, power-efficient, and easily integrable into RF front-ends and mixed-signal systems. Its ability to operate with low supply voltages makes it suitable for integration with the harvested power source. The combination of an optimized rectifier and a CMOS VCO supports complete system-level functionality for IoT nodes, biomedical implants, wearable electronics, and smart sensor platforms. Together, they demonstrate a practical pathway toward fully integrated, self-powered mixed-signal RF systems, addressing both power and frequency control requirements with minimal component count and silicon area. This unified approach opens new possibilities for low-cost, compact, and scalable designs in the domain of ambient-powered wireless electronics.