Fully integrated high accuracy continuous current sensor for switching voltage circuits

This paper presents the design of a novel integrated continuous current sensor (CCS) circuit for class-D audio amplifier and current mode controlled DC-DC converter. The proposed current sensor has the capability of sensing either positive or negative current of off-chip inductor continuously. Additionally, fast transient response with low quiescent current has been achieved. Furthermore, a calibration technique has been developed and attached to current sensor circuit to eliminate performance deterioration due to process, supply, and temperature (PVT) variation. The proposed CCS has been implemented using TSMC 65 nm technology. Simulation results show that the proposed CCS is able to operate with switching frequency up to 1 MHz at only 75 μA quiescent current. The overall accuracy of proposed CCS is greater than 95% over all process corners and temperature variation from -40°C to 125°C, and supply variation from 2.5 V to 2.9 V.