# Articles Tagged with ''PDN''

## Causality Problems in Power Delivery Networks

This paper is a case study on causality problems in PDNs during power-aware SI simulations. It covers the causality of a PDN, and it reveals the impact on a design if a causality check is not done on the PDN for the package or board.

## The 2-Port Shunt-Thru Measurement and the Inherent Ground Loop

When you make a 2-port shunt through measurement using a commercial vector network analyzer the measurement includes an undesirable ground loop. Left uncorrected, the ground loop introduces significant errors. This paper shows how to solve this problem.

## Target Impedance Is Not Enough

Target impedance has become a standard tool when designing a power distribution network (PDN). It establishes a limit to the highest impedance the power rail on the die should see looking into the PDN. If the PDN impedance stays below this limit, even the worst-case transient current from the die will generate an acceptably low rail voltage noise.

## VRM Modeling: A Strategy to Survive the Collision of Three Worlds

This paper reviews four levels of VRM models that VRM designers, board level interconnect designers, semiconductor designers, and product managers often use to explore design tradeoffs throughout the PDN system. The choice of which one to use involves considering engineers’ levels of expertise and what problems they expect to analyze. Some tradeoffs and relative merits of the models are described.

## Executive Q&A: David Kohlmeier, Mentor, A Siemens Business

SIJ talked with Dave Kohlmeier about industry trends, how to foster innovation, and what today’s EDA customers need most.

## How to Measure Shared On-Die Power Rails

If the die's I/O power rails are shared by the core power rails, here's a way to get your core power-rail measurements anyway.

## Overview and Comparison of Power Converter Stability Metrics

Power conversion circuits with control loop(s) are everywhere in electronic systems. We must establish stability and performance metrics for control loops and their circuits. However, generally accepted metrics may not be good enough. Is a crossover frequency with 45 degrees of phase margin and 10 dB of gain margin enough? How can we relate phase margin to peaking in the impedance profile and transient noise requirements? This article aims to answer these and other questions.

## Characterizing and Selecting the VRM

VRMs and VRM controllers are often selected based on size, efficiency, price, or a relationship with the manufacturer. This often leads to a poor VRM selection, requiring additional engineering resources, greater time to market, as well as, higher BOM costs to correct the deficiencies. In this article, we evaluate the choices, define some useful figures of merit, and provide specific selection suggestions.