Elimination of Sampling-Induced Dead Bands in Multiple-Sampled Pulsewidth Modulators for DC-DC Converters

This letter presents a linearization technique for multisampled pulsewidth modulators (MSPWMs) employed in digitally controlled dc–dc converters. MSPWMs, i.e., PWMs operated at a sampling rate strictly higher than the switching frequency, greatly reduce the significant small-signal phase lag exhibited by conventional single-sampled PWMs, thus enabling for high-bandwidth design. On the other hand, the increased sampling frequency generates nonlinear phenomena known as samplinginduced dead bands, which represent zero differential gain regions in the modulator transcharacteristic that degrade the system closed-loop operation. This letter proposes a correction algorithm that allows for dead band removal, thus linearizing the PWM behavior, while still retaining the multisampling benefits. This result is achieved by a simple solution that can be easily implemented with simple hardware requirements. Simulation and experimental results on a dc–dc synchronous buck converter are provided to show the effectiveness and overall simplicity of the proposed solution.