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In the multiphase interleaving buck converters with peak-current control, the sample-hold effect limits the bandwidth of the voltage-regulation loop. For higher bandwidth and better transient performances, this paper presents two methods to reduce this limitation. To decrease the quality factor of the sample-hold related double poles, external ramps are inserted to the modulators. To increase the effective sampling frequency, the phase inductor currents are coupled, either through feedback control or by the coupled-inductor structure. In addition, a small-signal model including the sample-hold effect is derived for the coupled-inductor buck to explain the improvement. High-bandwidth designs are verified by the simulation and experimental results.