An electromagnetic energy harvesting system for low frequency applications with a passive interface ASIC in standard CMOS

This paper presents a compact energy harvesting system, which consists of an electromagnetic (EM) generator converting ambient low frequency vibrations to DC voltage by using a highly efficient full-wave rectifier in a System-on-Package (SoP). Frequency Up-Conversion technique has been utilized by the in-house EM transducer to harvest energy from very low frequency vibrations (<5 Hz). The interface ASIC is a passive rectifier based on the boot-strap rectification (BSR) technique to decrease the effective threshold voltage of the utilized diodes, attaining a high AC/DC conversion efficiency in a standard 0.35 μm CMOS process. The energy harvesting system has been tested within a frequency range of 2–10 Hz. The autonomous system with a volume of 21 cm3, delivers 128 μW DC power to an 80 μA load at an external vibration frequency of 2 Hz and 72 mg peak acceleration while a 1.6 V DC voltage is generated. The maximum overall power density is measured as 6.1 μW/cm3. Furthermore, the reliable operation of a commercially available temperature sensor, as a realistic load, has also been demonstrated by using the energy harvester as a DC supply.