Differential zero compensator in delay-ripple reshaped constant on-time control for buck converter with multi-layer ceramic capacitors

A differential-zero-compensator (DZC) technology in constant on-time control dc-dc buck converter which can be applied for the ceramic capacitors is proposed in this paper. Ceramic capacitors are widely used in industry because its low cost. However, the stability often confronts with the sub-harmonic problem related to the incorrect output capacitor and ESR used. In this paper, the proposed DZC technology remits the limitation without adding extra pins and the complexity of circuit still maintain simple. Furthermore, the proposed self-compensated on-time timer (ONT) offers the reliable on-time period with linear solution. In addition, utilizing ceramic capacitor derives smaller ripple of 8mV at 8A. High efficiency of 92.5 % can be guaranteed due to the small ESR value. Stability criteria analysis and simulation results demonstrate that the stability can be ensured even if the ESR is small than 2mΩ.