This brief presents a pulsewidth modulation buck converter with an adaptive ramp amplitude control. The proposed buck converter can improve the load transient response and the reference tracking speed. A chip was fabricated in a 0.18-μm CMOS technology. Measurement results showed that the overshoot/undershoot at the output during the load transient period was reduced by up to 57% for a 450-mA load current step and that the reference tracking speed was improved by up to 71% for a 1.5-V output voltage change. The measured maximum power conversion efficiency was 92.6% at 3-MHz switching frequency when input and output voltages are 3.3 and 2 V, respectively.

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