Differential Impedance Transmission Line Calculator:Thank you for using UltraCAD's Differential Impedance Calculator. This is a follow-on calculator to UltraCAD's highly popular ULTRACLC Transmission Line Impedance Calculator, introduced many years ago. That calculator has been downloaded and used by countless designers all over the world. But it did not calculate differential impedance. This new version does. And this new version is substantially more accurate. This version still calculates single-ended impedances without cost to the user. A nominal license fee and USB dongle are required for differential calculations. See the section on licensing if you would like to obtain one, and for information on how to administer a license once it is obtained. We hope you like it.