A current-mode DC-DC buck converter with adaptive zero compensation

To achieve fast transient response for a DC-DC buck converter, an adaptive zero compensation circuit is presented. The compensation resistance is dynamically adjusted according to the different output load conditions, and achieves an adequate system phase margin under the different conditions. An improved capacitor multiplier circuit is adopted to realize the minimized compensation capacitance size. In addition, analysis of the small-signal model shows the correctness of the mechanism of the proposed adaptive zero compensation technique. A current-mode DC-DC buck converter with the proposed structure has been implemented in a 0.35 mu m CMOS process, and the die size is only 800 x 1040 mu m(2). The experimental results show that the transient undershoot/overshoot voltage and the recovery times do not exceed 40 mV and 30 mu s for a load current variation from 100 mA to 1 A.