IEEE RFID-TA 2026

In passive UHF RFID systems, the instantaneous available power is insufficient to directly operate power intensive components such as sensors and microcontrollers. Therefore, energy must be harvested and accumulated over time, enabling short bursts of operation for sensing and data transmission. 

Conventional rectifier based harvesters suffer from leakage and efficiency limitations, while existing charge pump solutions assume sufficient input energy and exhibit performance degradation due to increased stage count and switching losses. This motivates efficient energy harvesting solution for energyconstrained RFID sensor nodes. 

This paper presents a hybrid charge pump architecture for passive RFID sensor systems. Fibonacci and multiphase voltage doubler (MPVD) topologies are analyzed in terms of output impedance, gain, and efficiency characteristics. Based on this, a configurable hybrid architecture is proposed to maximize efficiency across the output voltage range. The gain stages are adaptively controlled with output voltage to improve energy transfer efficiency and reduce charging time of off-chip storage capacitor.

The measurements show approximately 50% reduction in charging time of off-chip storage capacitor compared to a fixed-gain implementation, with a peak efficiency of 80%. The proposed architecture is validated in a commercially available 180-nm CMOS technology and operates from a 1.2 V supply, making it well suited for battery-free sensing and IoT applications