1.5V continuous-tracking current sensing circuit with high accuracy for DC-DC buck converter

A low voltage current sensing circuit is presented in this paper. The proposed current sensing circuit performs continuous-tracking with high accuracy over 98% is achieved. The current sensing circuit is implemented with a standard 0.18μm CMOS process at 1.5V supply voltage. The power efficiency obtains 89% over the maximum load current of 540mA. Wide operation frequency range from 400kHz to 25MHz speeds up the tracking time. Off-chip inductors and capacitors can effectively decrease the voltage ripple. Area efficiency brings the benefit of low cost to the proposed current sensing circuit.