Differential Impedance Calculator
Current version: 2.1

UltraCAD's new Differential Impedance calculator will calculate single-ended and differential impedance for the common configurations we all deal with:

            Microstrip
            Embedded Microstrip
            Stripline
            Edge-coupled Asymmetric Stripline
            Broadside-coupled Asymmetric Stripline

Given a value for impedance, it will (in most cases) calculate the other variables we need during the design process. So it will help answer questions like:

        What width trace do I need to hit a 75 Ohm differential impedance?
        How far apart do my planes need to be?
        How sensitive is my design to variations in Er?
        Will a change in trace thickness impact my design?

In addition, the calculator calculates propagation time, Co, and Lo for the traces. While our earlier calculator does some of these things, it is based on a different calculational technology and is not nearly as accurate as this new version is. The older calculator will likely be phased out as the new calculator gains acceptance.

Beginning with version 2.01, UCCALC also calculates common mode impedance.

NOTE: We have discovered an annoying bug that requires the entry of the trace separation variable, S, in certain single-ended calculations even though those calculations do not depend on S. That bug has been fixed in the current version, 2.1. All prior licenses are still valid with this version.

Click here to see a .wmv video describing this calculator. (Approx. 4 MB, 3 minutes)

*  Most single-ended calculations are free in this new version. Differential calculations require a license and a USB dongle. The Operator's Manual contains specific information regarding specifications and which operations require a license.

Go to this page for download information, including how to download the Operator's Manual. The Operator's Manual is a *.pdf version of the help file and describes the calculator in detail, including its specifications.

Go to this page for some screen shots of some sample calculations.

Go to this page for licensing information and instructions on how to acquire your license.

Go to this page for UltraCAD's FAQ (Frequently Asked Questions) regarding the calculator.

Operating System Requirements:

This calculator, and the USB license dongle, are designed to run on Windows 98/ME/2K/XP. The freeware version will run on WINNT, but NT was not designed to recognize USB devices, so it is not likely you can make the dongle work on NT. We do not support NT installations. 

The dongle requires a free USB port.

Click on logo to return to UltraCAD's Calculator page.