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Training > VRM Modeling & Decoupling Workshop
NEW Non-Invasive Measurement Information
Hands-On VRM Modeling and Decoupling Optimization Workshop (1-Day)
Course Overview
It seems that almost all circuits today include high speed devices including FPGAs, memory, CPUs, and data transceivers.  Meeting the power quality requirements of these devices is a major challenge.  Continuously increasing edge speeds, decreasing rail voltages decrease and shorter design cycles increase the challenges.  Multilayer circuit boards require are expensive and the fabrication cycle is long, so we need to minimize the number of printed circuit board revisions.  There are so many voltage regulators to choose from, how do we either select one or design one, especially when so few component details are provided by the manufacturers?

This VRM modeling and decoupling seminar addresses all of these issues in four sections.

What You Will Learn

  • Introduction to power integrity and the role of the VRM, the printed circuit board and the decoupling
  • S-parameters, capacitor measurement and parameter extraction
  • VRM characteristics and extraction of a measurement based model
  • A simple guide to printed circuit board decoupling and how the VRM can make life difficult

Lead Instructor, Steve Sandler
See Steve's bio on the main training page.

Simulating and Modeling for PI
Power rail impedance resonances can result in noisy power planes that fail to meet the strict dynamic regulation requirements of today’s high speed circuits.  One resonance is bad and multiple resonances can result in rogue waves.  Some basic transmission line theory how the VRM and the system interact with each other and how we can prevent these disastrous results.

Capacitor Measurement and Modeling
Accurate capacitor models, both with and without the mounts are essential for both SPICE simulation or EM simulation and the models are different.  With a small modification of a standard VNA measurement we can make perfect measurements and models every time.

VRM Characteristics and Extracting an Accurate Measurement Based Model
Much of what we need to know about the VRM is not published.  Fortunately, a few simple measurements are all we need to create an accurate large signal and small signal model.  This model can provide AC, DC, Transient and even Harmonic Balance simulation of single phase and polyphase VRM’s of voltage mode and current model VRM’s. 

The Simplest Guide to Power Rail Decoupling
High frequency decoupling is required at the high-speed circuits to maintain the proper dynamic voltage limits.  The selection of these capacitors is far from arbitrary and improper selection can make things worse the old-school rule of thumb to use different values of capacitors, usually one or two values per decade will make things worse, not better.  The selection of the decoupling capacitors is neither arbitrary or difficult.  One magic equation tells us the precise characteristics of the decoupling capacitors.

One measurement tells us what is right, what is wrong and how to optimize the power rail.  You just need to know how to read the curve.

  Workshop Synopsis
This hands-on measurement workshop introduces you to basic Power Integrity concepts, focusing on the process of modeling the VRM (Voltage Regulator Module) and power supply decoupling.

The Voltage Regulator Module (VRM) is a fundamental element in the Power Distribution Network (PDN) with system level consequences heavily impacting Power Integrity. Very few, if any, manufacturers provide high fidelity VRM models and much of the data required to construct your own model is not published.

In this compact one day workshop, you will be guided through all measurement and simulation steps required to generate a measurement based VRM model.

Each theory step is followed by practical measurements performed in small groups. This workshop introduces a measurement based, non-linear VRM model that simulates very quickly while supporting both, switching and AC characteristics. The model includes PSRR and input impedance, including negative resistance, as well as VRM output impedance and supports effects of decoupling capacitors as well as PCB influences via EM simulation.

The Workshop includes documentation, snacks, lunch & drinks, and Steve Sandler’s book on Power Integrity.

Hands-On Measurements

  • Measuring cables, transmission lines, and PCB striplines
  • Characterizing capacitors using 1 and 2 port impedance measurements including the capacitor mount
  • Measuring VRM output impedance and PSRR to make a model
  • Measuring and Optimizing Decoupling
  • Understanding DC Blocks and the 2-Port Shunt Thru Test Setup
  • Clock Jitter Troubleshooting



Power Integrity Book Cover
Table of Contents | Power Integrity Book Page