Method for Transient Behavior Modeling of a Multiphase Voltage Regulator Module for End-to-End Power Integrity Simulation

Abstract

Accurate end-to-end power integrity simulations require models that include every component in the power distribution network, including voltage regulator modules (VRMs) and on-die capacitors. However, including VRMs in power integrity simulations has been challenging, because power electronic simulation tools are not compatible with typical power integrity simulation tools, and encrypted VRM models for SPICE tools are typically not sufficiently accurate to capture the non-linear behaviors under various load conditions. Herein, a SPICE-compatible behavior modeling method is proposed, which is applied and validated for a practical multiphase VRM in a mobile platform. The simulation model adequately captures the control loops of the VRM, such as single-voltage and multiple current feedback loops. By combining the parameter-based equations from the voltage and current feedback networks, the model reproduces pulse-width and pulse-frequency modulation-based VRM operations. For validation of the behavior model, the design parameters are determined through a two-step process. Finally, the proposed behavior modeling method is experimentally validated with an evaluation board with various load conditions.