High input voltage (48 V) multiphase VRM with feed-forward of the load current for fast dynamics

This paper shows the goodness of the multiphase half bridge topology (two phases) for high input voltage (48 V), low output voltage (2 V) and high efficiency applications. The power stage is designed with a high current speed capability (20 A/μs) to reduce the size and cost of the output capacitors. The strong influence of the dynamics specs on the design of the power stage is analyzed in detail. Average current mode control is applied to assure current sharing between both phases and feed-forward of the load current (Richard Redl et al. 1986) is used to maximize the dynamic response of the average current mode control. Performance of this control method are explored and compared with other techniques.