A self-powered and efficient rectifier for electromagnetic energy harvesters

This paper presents an interface circuit for efficient rectification of voltages from electromagnetic (EM) energy harvesters operating with very low vibration frequencies. The interface utilizes a dual-rail AC/DC doubler which benefits from the full cycle of the input AC voltage, and minimizes the forward bias voltage drop with an active diode structure. The active diodes are powered through an AC/DC quadrupler with diode connected (passive) transistors. The interface system has been validated to drive 22 μA load at 1.1 V, with 86% efficiency, when 0.1g vibration is applied to an in house energy harvester at 8 Hz. The circuit is functional down to 150 mV input. The rectified voltage deviates at most 38 mV from the theoretical value of twice the input peak voltage. The system was demonstrated for feasibility in portable applications through a prototype placed to the waist of a jogger.