An Asynchronous AC-DC Boost Converter With Event-Driven Voltage Regulator and 94% Efficiency for Low-Frequency Electromagnetic Energy Harvesting

This brief presents an asynchronous AC-DC boost converter with a high power conversion efficiency (PCE) and a low start-up voltage. The converter consists of a self-powered rectifier with unbalanced comparator, followed by a hysteresis DC-DC boost converter with an ‘event-driven’ regulation loop, enabling boost conversion and output regulation without the need for a system clock, leading to significant reduction of the driving power loss and thus improvement of the PCE. The converter can be started up from an input AC voltage with 500 mV amplitude, achieving a maximum PCE up to 94% with reduced chip-to-chip variation as low as 4%, delivering
$103~\boldsymbol{\mu }\text{W}$
output power. The chip has been fabricated in 180 nm standard CMOS process with a 0.11 mm
²
core area, targeting on the low-frequency electromagnetic (EM) energy harvesting.