Comparison of state-of-the-art digital control and analogue control for high bandwidth point of load converters

The purpose of this paper is to present a comparison of state-of-the-art digital and analogue control for a buck converter with synchronous rectification. The digital control scheme is based on a digital self-oscillating modulator that allows the sampling frequency to be higher than the switching frequency of the converter. Voltage mode control is used in both the analogue and digital control schemes. The experimental results show that it is possible to design a digitally controlled buck converter that has the same performance as can be achieved using commercially available analogue control ICs. The performance of the analogue system can however be increased by using a separate operational amplifier as error amplifier. Thus analogue control is still the best option if high control bandwidth and fast transient response to load steps are important design parameters.