Voltage regulation of a series-stacked system of processors by differential power processing

Series-connected power delivery architectures have been shown to radically improve efficiencies for power delivery to servers and digital circuits. This paper investigates the element-to-element differential power processing topology. An average model for the series-stacked system with voltage regulating converters is proposed to aid in the closed-loop control design. Voltage regulation of the stack is simulated with a conventional 2-pole, 2-zero compensation scheme. Limitations regarding the number of cores that can be stacked in series and possible ways to overcome the limitations are also discussed. A modification to the element-to-element topology which improves transient response of the system is also suggested.