An efficient fast response hysteresis buck converter with adaptive synthetic ripple modulator

An efficient fast response hysteresis buck converter is presented. The adaptive synthetic ripple modulation (SRM) technique is combined with dynamic hysteresis band to achieve better transient response as well as conversion efficiency. The adaptive SRM provides a saw tooth waveform with the slope adjusted according to load conditions. The hysteresis band and thus the switching frequency are also adjusted automatically according to load conditions. The buck converter is further put into the discontinuous-conduction mode (DCM) for better conversion efficiency at light load conditions. The circuits are implemented using a standard 2P4M 0.35μm CMOS process. The design has the output recovery time less than 9μs for load transient between 100mA and 600mA. The efficiency is higher than 90% for operation voltage range from 2.7V to 4.5V under both light and heavy load conditions.