A high power density 1.75 mm2 fully integrated closed-loop buck converter with varactor control scheme

A high power density fully integrated DC-DC power converter is realized with improved quality factor on-chip inductor and high frequency switching. The power converter output voltage change is non-linear with Pulse Width Modulation (PWM) at high frequencies, hence a new control scheme with a varactor to adjust output voltage has been proposed in the paper. Detailed analysis of the design and simulation of a 1.75 mm² fully integrated closed-loop buck converter in TSMC 0.25 μm technology is presented. The power converter takes a 3.3 V DC input and switches at 1.0 GHz to produce an output voltage of 1.5 V supplying 45 mW of power, giving a power density figure of 25.71 kW/m². The proposed closed-loop DC-DC converter settles in less than 600 ns.