An intelligent pulse width modulation (PWM) controller adapts a switch mode power supply (SMPS) system's operating parameters to optimize efficiency, remove hot spots and isolate faults by integrating a microcontroller, PWM digital circuits and analog circuits into a single integrated circuit, thereby reducing the number of external connections, silicon die area and integrated circuit packages. A lossless inductor current sense technique integrates a matched, tunable complimentary filter with the intelligent SMPS controller for accurately measuring current through the power inductor of the SMPS without introducing losses in the power circuit. The complimentary filter is adjusted by the microcontroller to significantly reduce the effects of component tolerances, accurately measuring the power inductor current for precise closed loop control and over current protection. The frequency pole and gain of the complimentary integrated filter can be adjusted on the fly in order to adapt to dynamically changing operating conditions of the SMPS system.