Wide-Bandwidth Digital Multi-Phase Controller

In this paper we present a new approach to wide-bandwidth digital control for interleaved multi-phase converters. The approach is based on the view of the multi-phase converter as a multi-level power D/A converter where the output voltage is sampled and the command is updated at the rate of Nf s where f s is the per-phase switching frequency and N is the number of phases. In contrast to alternative approaches where the bandwidth is limited to a fraction of f s we show that a bandwidth that scales with Nf s is achievable. A zero-error-bin approach, which is inherent to the digital controller implementation, is proposed to address the effects of phase-mismatches and sub-harmonic ripples on the stability of the wide-bandwidth controller. Simulation and experimental results are shown for a 16-phase synchronous buck converter operating at 1.56 MHz per-phase switching frequency.

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