An Ultra-Fast AOT Buck Converter Using Capacitor Current Sensing Technique

This paper presents an ultra-fast adaptive on-time (AOT) buck converter that utilizes a capacitor current sensing technique for superior transient performance. The design features an on-chip self-calibrated RC network that automatically matches the output capacitor impedance, enabling accurate real-time load current detection. This sensed current directly drives an optimal timing generator that computes and applies ideal switching patterns within a single cycle to counteract load transients. Consequently, the implemented architecture achieves time-optimal control with minimal voltage deviation. Fabricated in a 180 nm BCD process, the converter occupies 3.67 mm$^{2}$and achieves 93.9% peak efficiency. Experimental results demonstrate consistent time-optimal response within one switching cycle across varying operating conditions, including different output voltages, output capacitors, and inductor values.