A Gm-Ramped Interleaving Technique with Adaptive-Extended TON Control (AETC) Scheme for Multi-phase Buck Converter Achieving Fast Load Response

This digest proposes an interleaving technique for multiphase constant on-time (COT) buck converter based on gm-ramp modulation. Without any user predefined load transient threshold voltage, the proposed technique can automatically turn on two phases immediately to recover the energy loss. Besides, an adaptive-extended TON control (AETC) mechanism is adopted to overcome the steady state switching frequency variation without shrinking the on-time compare to the conventional adaptive on-time (AOT) methodology. A CMOS dual phase buck converter is realized in a 0.18um process to verify these two techniques. The chip pre-simulation results show that the gm-ramped interleaving technique and AETC are suitable for a 25 MHz high switching frequency operation without extra summing amplifier which means more signal manipulation delay. Full transistor level results show that, during 2.5 A load current step changes with 1A/1ns slew rate, the converter is able to regulate the output voltage from within 0.4 us with less than 45 mV undershoot while the output capacitor is only 2 uF.