LAUSR

This paper presents a self-powered interface enabling battery-like operation with a regulated 3 V output from ac signals as low as 0.4 Vpeak, generated by electromagnetic energy harvesters under low frequency vibrations. As the first stage of the 180 nm standard CMOS circuit, harvested signal is rectified through an ac/dc doubler with active diodes powered internally by a passive ac/dc quadrupler. The voltage is boosted in the second stage through a low voltage charge pump stimulated by an on-chip ring oscillator. The output is finally regulated to 3 V at the last stage. The voltage doubling rectification stage deviates by less than 40 mV from ideal expectation for the validated 0.15–1 V input voltage range. The full system delivers 3 V output to 4.4 MΩ load for input voltage of 0.4 V peak, which is the lowest operable input voltage in the literature. The demonstrated system generates 9 μW of dc power with 3 V stable output for 32 μW input, whereas the circuit is able to supply even more output power for higher input power levels. The maximum efficiency of the rectification stage is 86%, while the full system efficiency is 37% and 28% for unregulated and regulated operation, respectively, when interfaced to an in-house electromagnetic energy harvester under 8 Hz 0.1 g vibration.