An optimal power management circuit with a dynamic subthreshold start‐up for thermal energy harvesting

Abstract

This work's power management circuit (PMC) employs optimum power point (OPP) instead of conventional maximum power point (MPP) extraction from the thermoelectric generator (TEG) for efficient source to load energy transfer. Based on postlayout verification of the TSMC 180-nm deep submicron model, this PMC generates above 100 μW of power with a regulated output of 2.5 V within 40 ms from 285-mV cold-start. The main contribution here is the constant time OPP extraction technique at 125.33 μs. Also, the PMC is almost fully on-chip with layout area of 3.8 mm by 3.25 mm for R TEG between 0.29 Ω and 4.17 Ω. OPP can be achieved by matching these R TEG values to the corresponding off-chip inductor, L. Using an overall figure-of-merit (FOM) to evaluate different design goals results in overall OPP-based PMC having at least 2.85 times superior FOM compared to prior arts with MPP-based schemes. This overall improvement in speed, power, and pumping efficiency facilitates battery-less solutions in TEG-based wearable sensor applications. K E Y W O R D S cold-start, optimum power point, power management circuit, thermal energy harvesting