Multiphase Constant-On-Time Minimum-Deviation Controller for Modern Processors

In Voltage Regulator Module (VRM) applications, rapid dynamic load conditions often lead to significant output voltage deviation and negatively impact the dynamic efficiency of converters optimized for static efficiency. This paper proposes a novel multiphase Constant-On-Time Minimum Deviation (COT Min Dev) Controller to mitigate dynamic losses and reduce converter sizes. This marks the first application of a Minimum Deviation Controller in a multiphase system, validated on a 4-phase buck converter with a 12 V input and 1 V output, achieving a reduction in output voltage deviation from 280 mV to 80 mV during a 10 A - 90 A load step. Additionally, it was validated on a 3-level 4-phase buck converter prototype, where the output voltage deviation was reduced from 280 mV to 125 mV for the same load step, with input voltage initial drop eliminated. The experimental results demonstrate effective phase balancing, enhanced transient performance, and a reduction in converter size.