Battery level A/D conversion with fuel gauge sense voltage cancellation in 40 nm CMOS technology

Abstract

A new integrated approach for battery voltage conversion inside portable devices is presented. It is specifically suited for latest Fuel Gauge techniques and exploits an A/D converter that operates as a General Purpose ADC inside the system. A peculiar solution for an analog cancellation of the Coulomb counter sense resistor voltage drop on the battery level measurement is disclosed. A prototype made by this battery voltage buffer and a 10-bit A/D converter has been integrated in a 40 nm CMOS process with double oxide option, resulting to a total power consumption of about 950 μW, and an active area of 0.174 mm2.