High-Frequency Dynamic Current Sharing Analyses for Multiphase Buck VRs

Under high-frequency repetitive load transients, multiphase voltage regulators suffer from beat-frequency oscillations of the phase currents. To investigate this issue, this paper develops a methodology based on the multifrequency model with describing functions. The phenomenon of beat-frequency oscillation in phase currents is explained. The influences from the interleaving operation are identified. Using peak-current control as an example, the magnitude of beat-frequency oscillations is predicted by a proposed model that considers sideband information. To reduce this oscillation without impacting the voltage regulation, several solutions are proposed. Experimental and simulation results are provided as verification of the analyses and solutions.