A Sensorless Adaptive On-Time Control Buck Converter with Fast Transient Response

This paper presents a sensorless Adaptive On-Time (AOT) controlled buck converter that achieves fast transient response without inductor current sensing. The converter operates at approximately 1 MHz with reduced switching-frequency variation over a 3.0–3.6 V input range, a 1.5–2.5 V output range, and load currents from 100 mA to 500 mA. The proposed converter is implemented in a UMC 0.18-µm 1P6M CMOS process with a chip area of 798.66 × 614.3 µm2. Simulation results show undershoot and overshoot voltages of 23 mV and 36 mV, with recovery times of 1.66 µs and 2.94 µs, respectively. The switching-frequency variation is limited to within ±3%, and the peak efficiency reaches 97.71%.