Cadence Design Systems has said it will appeal against the German Federal Patent Court's decision to overturn a key patent used in its suit against Mentor Graphics over the technology used in Mentor's SimExpress emulators.
Using US versions of the patent, Cadence has successfully prevented Mentor from shipping either SimExpress or the second-generation Celaro emulator into the US.
The decision by the German court came as the result of a case brought by another one of the big-four EDA companies, Avant. The European patent No.0437491, also known as the Butts patent, covered some designs that use networks of programmable devices.
Dean Freed, general counsel for Mentor, said: "We believe that this ruling has important implications to our litigation against Cadence."
Chris Tice, general Manager of Cadence's Quickturn subsidiary, said: "The German Federal Patent Court's decision was an oral ruling from the bench. We will file an appeal once the court's written opinion is issued.
"It is important to note that this ruling has no legal effect on the April 1999 decision of a German infringement court which found that Mentor Graphic's SimExpress product infringed this patent and issued an injunction prohibiting Mentor from selling any product in Germany that infringes Quickturn's patent rights."