An efficient integrated interface electronics for electromagnetic energy harvesting from low voltage sources

This paper presents a fully-integrated self-powered interface circuit for efficient rectification of the signals generated by vibration based low-voltage electromagnetic (EM) energy harvesters. The circuit utilizes an improved AC/DC doubler structure with active diodes to minimize the forward bias voltage drop for enhancing the rectifier efficiency. The comparators in the active diodes are powered internally by another passive AC/DC doubler with diode connected transistors. The performance is maximized through custom-designed comparators for each of the positive and negative terminals of the dual rail output. Measurement results show that the system is capable of driving 40 μA load at 0.61 V, with 67% power conversion efficiency, when operated together with an inhouse EM harvester subjected to vibrations at 10 Hz, 2.5 mm peak-to-peak displacement with 0.5 g acceleration. The circuit is able to rectify AC inputs with peak amplitude as low as 100 mV.