An Autonomous Piezoelectric Energy Harvesting IC Based on a Synchronous Multi-Shot Technique

This paper presents a fully autonomous integrated circuit (IC) dedicated to piezoelectric harvesters. The novel Multi-Shot Synchronous Electric Charge Extraction (MS-SECE) performed by the IC optimizes the energy transfer from a highly charged piezoelectric harvester to a low voltage storage element. The system deals with piezoelectric powers in the 10 mu W to 1 mW range and handles very high piezoelectric voltage values (100 V) thanks to the off-chip components around the IC. The IC has been fabricated in AMS 0.35 mu m 3.3 V technology and its low power consumption (1 mu W @ 5 Hz) is particularly suitable for low frequency harvesters. MS-SECE increases the extracted power compared to the Maximum Power Point Tracking (MPPT) technique but it also improves the efficiency by up to 25% compared to standard SECE. Furthermore, MS-SECE allows the use of small off-chip components: an efficiency of 61% has been reached with a 125 mm(3) coupled-inductor. Finally, the proposed power management circuit self-starts, works without any battery and its overall volume is expected to be less than 1 cm(3).