Title:  Low-VIN Maximum-PO Micro-scale Thermoelectric CMOS Battery Charging Voltage Regulator

Committee: 

Dr. Rincon-Mora, Advisor       

Dr. Li, Chair

Dr. Brand

Abstract: The objective of the proposed research is to study, develop, test, and assess low-input-voltage maximum-output-power micro-scale switched-inductor CMOS battery–charging voltage regulators for wireless microsensors that draw power from thermoelectric CMOS generators (to supply the system, replenish the battery, and draw battery assistance when needed). One fundamental challenge is low input voltage because transistors cannot operate the system reliably with the 40–400 mV that these generators output. Another difficulty is low input power because drawing 3–10 µW reduces the already-low thermoelectric voltage by half. The third obstacle is charging, supplying, and assisting with one inductor because the silicon overhead of the additional circuits required leaks power that loads the thermoelectric voltage. Plus, the controller needed is complex and difficult to stabilize when the system is awake. This research therefore proposes to study the fundamental voltage and power limitations of switched-inductor boost converters. Exploring CMOS power stages that can supply the load, recharge the battery, and draw battery assistance with only a few nano-Watts is next. This research will then develop a controller that consumes low power and is widely stable. The ultimate goal is to design and build a switched-inductor CMOS battery–charging voltage regulator system that can harvest with low input voltages and supply the system, charge the battery, and assist the thermoelectric source. This way, tiny sensors can operate with lower input voltages and across longer periods.