Switched Inductor DC-DC Boost Regulator Using Voltage-to-Time Controller for TEG Applications

This paper presents a switched inductor (SI) DC-DC boost regulator designed for thermoelectric generator (TEG) applications. To boost and regulate the output voltage, two feedback loops are implemented which control the duty cycle of the SI clock. The first loop consists of a pulse skip modulation (PSM) controller that compares the load voltage and reference voltage. Based on the comparison output, the PSM will either pass or bypass the modulated pulse width signal generated from the second loop. The second loop replaces the conventional circuit design of the pulse width modulation (PWM) with a voltage-to-time converter (VTC). The VTC converts the difference between load and supply voltage to time delay resulting in a modulated pulse width. This work is the first to report on utilizing VTC circuit in the SI boost regulator. The proposed SI boost regulator is designed using 65 nm CMOS technology which converts the TEG voltage of 50 mV to support dynamic voltage scaling in the range of 0.6 V to 0.8 V. The PSM and PWM controller loops can tune the duty cycle of the clock in the range of 0 to 70%. It achieves a peak efficiency of 60.9% at 30 mu W load power. Comparing the proposed single-stage SI boost regulator with the conventional two cascaded stages of switched-inductor boost converter followed by switched capacitor regulator, the area is reduced by 9.6x and power efficiency is increased by 1.35x.