Using SIMetrix/SIMPLIS to address the PDN Problem


Previously Held on June 6th, 2024

In high-performance microprocessor applications, the power distribution network (PDN) refers to the network of components, interconnections, and printed circuit board paths used to distribute power from a switching power supply source to the input voltage pins of the microprocessor load. The proper design of the PDN is vital to ensuring that the microprocessor load receives the correct voltage and current overall operating conditions, including during current steps on the order of 1000 A and slew rates on the order of 1 A/ns. 

VRM and PDN schematic


In this webinar, we show how to take an automatically extracted Full PDN Spice model of the PCB layout parasitics and prepare that PDN model to be used in SIMetrix/SIMPLIS using the SIMPLIS PDN Parser.  We also show how to characterize the Full PDN model in SIMetrix Spice and then obtain optimized values for a Reduced Order PDN model that captures the parasitic inductive behavior of the Full PDN model. We demonstrate that the Reduced Order PDN can be used to handle the bulk of the power system design tasks, taking advantage of the substantially faster simulation times when compared with the Full PDN model.


We will walk through the following step-by-step procedure for analyzing the impact of a PDN of the PC Board layout on the performance of the power system for a high di/dt load.

  1. Extract Spice netlist of PDN from PCB layout
  2. Convert PDN Netlist to SIMPLIS and SIMetrix Compatible Netlists and Create Associated Symbol
  3. Using SIMetrix PDN test bench, characterize performance of Full PDN and R-Only PDN using worst-case expected load-transient current waveform
  4. Using SIMetrix testbench:
    1. Find optimum curve-fit values for Reduced-Order PDN model
    2. Compare performance of Full, R-Only, and the Reduced-Order PDN models with worst-case expected load-transient current waveform
  5. Using SIMPLIS testbench with complete SIMPLIS converter model:
    1. Compare system performance of Full, R-Only, and Reduced-Order PDN models

Link to Webinar Recording

A recording of the webinar can be viewed at this link: Using SIMetrix_SIMPLIS to address the PDN Problem (1:01:49)

Reference Materials

Schematics and presentation slides for the webinar can be downloaded here: