Design of A State Space based Unified Controller for Multi-Phase Point-of-Load Converters with Phase Dropping

Recent requirements for Point-of-Load converters target dynamic response and this can offer a new topic for applicative research. State Space based design for the feedback control system has already seen its success on digital implementation, and it is accompanied by a suitable support when designing for dynamic performance. Most recent Point-of-Load converters are built as multi-phase buck converters, with a phase dropping capability to maintain efficiency high at various load current levels. This paper introduces a novel State Space based design of the feedback control system for dynamic requirements. When imposing the same location of the poles and zero for any phase count case, the dynamic performance stays the same, irrespective to the phase dropping algorithm, even if phase(s) current feedback is also considered in the control system. Moreover, a unification of the gains is proposed so that transition of the control system from a phase count case to another implies minimal changes in feedback control. It is demonstrated how the method is valid for either analog or digital implementation. Both frequency domain and time domain aspects are thoroughly discussed for design details.