Precision PCB Design Software with a Differential Line Impedance Calculator

Zachariah Peterson
|  Created: May 19, 2020

Altium Designer’s differential line impedance calculator will set up your impedance controlled differential pair routing widths for you.


For better impedance control, use PCB design software you can trust.

One thing is for sure: When you are routing a high speed PCB design you are going to be working with impedance controlled routing and differential pairs. There have been trace routing tools available for a long time that help with differential pair routing, and designers have had access to impedance calculators to determine their trace widths. But to find a PCB routing system that calculates trace widths automatically factoring dielectric constants and the board layer stackup, and then automatically inputs that into the design rules, is a little more difficult. Then on top of that, finding a PCB design tool that will automatically calculate differential pair trace widths based on impedance calculations is almost unheard of. That’s when the engineering team at Altium Designer went to work to make sure you’re covered.

The new enhanced layer stack manager in Altium Designer will do all of what you are looking for in high speed impedance controlled routing, including calculating your diff pair widths. By entering your board layer stack materials from a premade materials library already equipped with information like dielectric constants, you can perform impedance calculations based on a number of routing profiles including stripline, microstrip, and differential pairs. That information is then made available to the design rules to set up the precise routing trace widths that your board needs. You will be hard pressed to find a PCB layout tool set that can help you more than Altium Designer can.

A Little More about Differential Pair Routing & Transmission Lines

Differential pair routing used to be a painful process of manually routing each trace of the pair tediously side-by-side to accomplish the task. Fortunately differential pair routing tools have given designers the ability to easily route the pairs together while obeying a set of design rules that governs trace widths, spacing, and how far the transmission pairs can diverge from each other. Understanding why differential pairs need to be routed so precisely for proper signal transmission is important to the entire high speed design process, and Altium Designer has provided some information here to help.

Understanding the Basics of Differential Pair Routing

Here is some basic information on what the purpose of differential pair routing is and how best to accomplish it.

Video screenshot Altium Designer layer stack manager for dielectric constant and characteristic impedance

Setting up the impedance calculator for differential pairs in Altium Designer

Routing Diff Pairs with a Differential Line Impedance Calculator for Optimal Signal Transmission

With Altium Designer, you no longer have to use a separate calculator to determine your trace widths and then enter those values into the design rules. Instead you set up your board layer stackup with materials and thicknesses, and then let the calculator input the correct trace widths into your design rules for the impedance values you have chosen. The next step is to do the same calculations for differential pairs, and the enhanced layer stack manager in Altium Designer will do just that. So put away your manual layer thickness, dielectric constant, and impedance calculations you’ve been using. Altium Designer can do the heavy lifting of differential pair impedance calculations for you from now on.

Altium Designer Does the Impedance Calculations Based on Your Layer Stack

With a handy library of board materials to choose from, Altium Designer will calculate your trace widths and thickness based on the impedance values that you need.

Screenshot of Altium Designer 3D diff pair routing and transmission lines

Routing differential pairs in Altium Designer

High Speed PCB Layout in Altium Designer

You’ve built the board layer stackup and prepared your design rules based on the trace width input from Altium Designer’s impedance calculator. But there’s a whole lot more to high speed digital design than just that. Fortunately, the advanced technology that you’ve seen in the layer stack manager and impedance calculator is just the beginning of what Altium Designer has in store for you. Based on a 64-bit multi-threading platform, Altium Designer has all the power that you will need for your high speed Printed Circuit Board designs.

Starting with component placement, Altium Designer has a multitude of different placement algorithms to help you locate and align your components the way that you need them to be. When it comes to trace routing you won’t find a more comprehensive set of routing tools than what’s available to you in Altium Designer. Whether it is interactive routing, auto-interactive routing, or auto routing, Altium Designer’s intelligent routing tools will help you to complete your routing quicker and more efficiently than you would have thought possible. To ensure that your high speed PCB is designed the way it needs to be, Altium Designer’s full array of high speed design rules and constraints will give you control over measured lines, routing topologies, and signal paths. Together with a powerful schematic editor and automated manufacturing output tools, Altium Designer has everything you need to successfully complete your high speed layout.

Powerful PCB Layout Tools to Get Your Job Done Right

There’s a lot to accomplish when working on a high speed PCB design, and Altium Designer has all of your needs covered with its powerful set of design tools.

There’s a lot that will go into your high speed design, and it starts with configuring the board layer stack in order for Altium Designer’s differential line impedance calculator to do its job. You’ve got the most amazing PCB design tools out there ready for you to use, so put Altium Designer to work for you today.

About Author

About Author

Zachariah Peterson has an extensive technical background in academia and industry. He currently provides research, design, and marketing services to companies in the electronics industry. Prior to working in the PCB industry, he taught at Portland State University and conducted research on random laser theory, materials, and stability. His background in scientific research spans topics in nanoparticle lasers, electronic and optoelectronic semiconductor devices, environmental sensors, and stochastics. His work has been published in over a dozen peer-reviewed journals and conference proceedings, and he has written 1000+ technical blogs on PCB design for a number of companies. He is a member of IEEE Photonics Society, IEEE Electronics Packaging Society, and the American Physical Society, and he currently serves on the INCITS Quantum Computing Technical Advisory Committee.

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