Analysis of multi-phase trans-inductor voltage regulator with fast transient response for large load current applications

Trans-inductor can be applied in a transient enhancement topology that uses the secondary windings of transformers to connect each phase of a multi-phase voltage regulator. The connection makes all the phases have a response when there is a load transient. Based on this, the resultant trans-inductor voltage regulator (TLVR) can achieve a significantly improved current slew rate. The current ripple maintains reasonable for each phase, making the design feasible to implement. In this paper, analysis of TLVR is presented and verified. For an eight-phase TLVR with COT, the current slew rate can be improved by 5.041 times in one case. It can reduce the undershoot from 50 mV to 17 mV for a load step from 40 A to 360 A in 160 ns. Overall, TLVR is a very suitable topology to be used in server CPU applications with extremely large load current slew rate.