A Single-Stage Bias-Flip Regulating Rectifier with Fully-Digital Fast-MPPT for Piezoelectric Energy Harvesting Achieving 9.3X Power Enhancement and 92.5% End-to-End Efficiency

Piezoelectric energy harvesting (PEH) has emerged as a promising solution for replacing conventional batteries in Internet-of-Things (loT) applications. Most prior works on PEH focus on highly efficient rectification; however, in a complete PEH system, maximum power point tracking (MPPT) and output voltage regulation should also be included, to maximize the rectification performance and provide a regulated output voltage. Unfortunately, present works either only employ 1 or 2 features [1]–[5], or employ the three features in cascaded stages, which result in cascaded power conversion efficiency (PCE) loss [6] (Fig. 1 top). Additionally, the buffering capacitor (C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REC</inf> ) significantly slows down the MPPT speed, which results in slow startup and inefficient transient tracking.