Trans- Inductors versus Discrete Inductors in Multiphase Voltage Regulators: An Analytical and Experimental Comparative Study

Traditionally, in the microprocessor industry, multiphase Voltage Regulators (VRs) are implemented with discrete non-coupled inductors in each phase. Recently, Trans-Inductor Voltage Regulators (TLVRs) have been proposed in the literature where the discrete inductors are replaced with transformers while all of their secondary windings are connected in series with a compensating inductor. Any sudden changes in phase currents will enable remaining phases to contribute during load transients improving the overall VR transient capability which decreases decoupling solution requirement of the converter. Although TLVR solutions have been widely adopted in XPU (CPU or GPU) industry, still there is a lack of in-depth analysis and comparative study in regard to the conventional discrete solutions. This paper aims to provide a holistic analytical and experimental comparative study over conventional discrete multiphase VRs versus TLVRs from various viewpoints, such as design, performance (steady state and transient), bandwidth, efficiency, power delivery (single-sided versus dual-sided), and cost.