An adaptable interface circuit for low power MEMS piezoelectric energy harvesters with multi-stage energy extraction

This paper presents a self-powered interface circuit to extract energy from ambient vibrations for powering up microelectronic devices. The system uses a MEMS piezoelectric energy harvester to scavenge power in 5 μW to 400 μW range. Synchronous electric charge extraction (SECE) technique is utilized to transfer harvested energy to output storage with the help of a novel multi-stage energy extraction (MSEE) circuit. The circuit is optimized in 180nm HV CMOS technology to operate with minimum power losses at the lowest allowable input power, and adjusts well to higher input power due to the MSEE circuit. The circuit operation was validated for a wide piezoelectric frequency range from 20 Hz to 4 kHz. Power efficiency between 62% and 81% has been achieved for the input power range of 5 μW to 173 μW at 198 Hz input vibration. MSEE provides up to 15% efficiency improvement compared to traditional SECE to keep power efficiency as high as possible for the full input power range.