A fast transient response synchronous Buck converter with modified ripple-based control (MRBC) technique

A new ripple controlled synchronous Buck converter featuring with improved transient response and low output voltage ripple is presented in this paper. The proposed modified ripple-based control (MRBC) technique adopting a novel ripple generate mechanism realizes the fast response ability by regulating the inductor current and output voltage through separate loops rapidly. In addition, a high-precision current sensor is utilized to form the current loop to improve the regulation accuracy. Meanwhile, the output voltage ripple is minimized by eliminating the requirement of a large ESR (equivalent series resistance) thanks to the introduced current loop. The proposed controller is implemented in a 0.5 μm BCD process of CSMC. Simulation results show that, during a 500 mA load current step change, the controller is able to regulate the output voltage to return to its nominal value within 2.6 μs with less than 50 mV overshoot/undershoot. The output voltage ripple is only 15 mV.