Modeling of High-frequency Switching Power Noise in Voltage Regulator Module

As switching power noise can cause severe power integrity (PI) and signal integrity (SI) problems on printed-circuit-board (PCB), the modeling of DC-DC buck converter, also known as voltage regulator module (VRM), is important for the analysis of noise coupling from the switching power noise induced by VRM to nearby signal and power nets. In this paper, the switching power noise from VRM is analyzed and then classified into two types of noise source, which are dv/dt noise and di/dt noise. The dv/dt noise is modeled by a resonator composed of the RLC series circuit. The di/dt noise is modeled by the inductor current with piecewise linear (PWL) format. The ringing of di/dt noise can be also modeled by the resonator created for the modeling of dv/dt noise. The simulation result proves the power noise generated by the proposed equivalent VRM model presents good agreement with the power noise generated by the HSPICE model of FETs provided by the VR manufacturer. The di/dt noise error ratio is less than 10% and the dv/dt noise error ratio is below 1%.