On-chip current sensing technique for CMOS monolithic switch-mode power converters

An on-chip current sensing technique, which is suitable for monolithic switch-mode power converter, is presented in this paper. This current sensing technique has been fabricated with a standard 0.6 mum CMOS process. Experimental results show that the switching converter can operate from 300 kHz to 1 MHz with the duty-ratio ranging from 0.2 to 1. The supply voltage of this current sensing circuit is from 3 V to 4.2 V, which is suitable for lithium ion battery applications. The discrepancy between the sensed signal and the inductor current is less than 4%, corresponding to 10 mA with load current 300 mA