Thermoelectric energy harvesting with 1mV low input voltage and 390nA quiescent current for 99.6% maximum power point tracking

In this paper, the proposed voltage trend detection (VTD) circuit effectively achieves high tracking efficiency in mixed-signal maximum power point tracking (MPPT) for the thermoelectric energy harvesting. The input power ranges from 42nW to 1.67mW and the input voltage can be lower to 1mV with a low quiescent current of 390nA when circuit is designed to operate in weak-inversion region. Consequently, the exponential relationship of the characteristic in the weak-inversion region can ensure that the tracking efficiency is higher than 99.6% and the tracking response time is less than 34ms.