A 60 mV Input Voltage, Process Tolerant Start-Up System for Thermoelectric Energy Harvesting.

This paper presents a 60 mV input voltage start-up system for thermoelectric energy harvesting. A new process tolerant inverter cell is proposed, which is functional at supply voltages as low as 60 mV. Using the proposed unit cell, a ring oscillator has been implemented. The ring oscillator is followed by 40 charge-pump stages, an ultra-low-power level detector, and a boost converter. The energy harvesting system can generate an output voltage of 1 V and delivers a maximum power of $4.5~\mu \text{W}$ from a 60 mV supply. This system has been implemented in a standard $0.18~\mu \text{m}$ CMOS technology, uses neither zero-threshold voltage (normally-on) negative-channel metal-oxide semiconductor nor microelectromechanical systems switches and occupies 3.3 mm2. [ABSTRACT FROM AUTHOR]