This paper presents a triple-band radio frequency (RF) energy harvesting system with 99.99% peak tracking efficiency and the triple band rectifier achieves the 4.6% improvement in the power conversion efficiency (PCE). The proposed system has a power range of −11 to 7 dBm with the three bands targeted on 900, 1900, and 2400 MHz. In this paper, the voltage and power characteristics of the triple-band rectifier at each band are extracted as raw data by measurement. The DC-DC boost converter is applied to achieve the maximum power point tracking (MPPT), which exploits the hill-climbing MPPT method. The method is implemented with register logics and power calculator. The converter’s voltage range of 0.1V to 2V is achieved, and the converter facilitates to achieve the highest tracking efficiency of 99.99%, 98.57%, 99.85% at each bands. The performance is verified through experimental results showing PCE improvement and over 87% tracking efficiency in a wide power range at triple bands. The triple-band rectifier with transmission line is fabricated on FR-4 substrate with active area 35.7 cm2, and the DC-DC boost converter with MPPT is implemented in a$0.18~\mu \text{m}$CMOS process with an active area of 0.94 mm2.

This paper presents a wide input range active rectifier using a bipolar-CMOS-DMOS (BCD) process with a high voltage conversion ratio (VCR) and high power conversion efficiency (PCE). The proposed rectifier ensures safe and robust operation under large input voltage variations, which can be caused by changes in the magnetic coupling or loading conditions. It supports an input voltage range 3-12 V with the adaptive delay-compensated active operation of the power switches. An active signal clamper and voltage-time hybrid gate control circuit with two compensation loops was proposed for the optimal gate transition of low-side NMOS switches. For high-side PMOS switches, a fully integrated low-power-consuming high-side driver is proposed to replace the conventional high-side gate driving structure. The proposed active rectifier was fabricated through a TSMC 0.18 μm BCD process. The measurement results show that the proposed rectifier achieves stable and well-delay-compensated active operation, resulting in a high VCR and PCE with a wide output power range from 4.5 to 288 mW. Peak VCR and PCE of 96.8% and 93.7%, respectively, were achieved.