Highly Efficient Rectifier and DC-DC Converter Designed in 180 nm CMOS Process for Ultra-Low Frequency Energy Harvesting Applications

This paper presents the integration of an AC-DC rectifier and a DC-DC boost converter circuit designed in 180 nm CMOS process for ultra-low frequency (<; 10 Hz) energy harvesting applications. The proposed rectifier is a very low voltage CMOS rectifier circuit that rectifies the low-frequency signal of 100-250 mV amplitude and 1-10 Hz frequency into DC voltage. In this work, the energy is harvested from the REWOD (reverse electrowetting-on-dielectric) generator, which is a reverse electrowetting technique that converts mechanical vibrations to electrical energy. The objective is to develop a REWOD-based self-powered motion (such as walking, running, jogging, etc.) tracking sensors that can be worn, thus harvesting energy from regular activities. To this end, the proposed circuits are designed in such a way that the output from the REWOD is rectified and regulated using a DC-DC converter which is a 5-stage cross-coupled switching circuit. Simulation results show a voltage range of 1.1 V-2.1 V, i.e., 850-1200% voltage conversion efficiency (VCE) and 30% power conversion efficiency (PCE) for low input signal in the range 100-250 mV in the low-frequency range. This performance verifies the integration of the rectifier and DC-DC boost converter which makes it highly suitable for various motion-based energy harvesting applications.