A US appeals court has upheld a district court's ruling that ordered Microsoft and Autodesk to pay millions of dollars to a Michigan company for patent infringement.

The court earlier this month affirmed an August 2006 decision by a lower Texas court, which upheld a jury decision in another district court awarding z4 Technologies $115 million from Microsoft and $18 million from Autodesk to settle a patent-infringement suit.

The Texas court also awarded $25 million more from Microsoft to z4 to settle the case, originally filed in September 2004, and denied Microsoft's request for a new trial.

The jury in Texas found that both Microsoft and Autodesk infringed on two patents held by z4 - US Patent No. 6,044,471 and US Patent No. 6,785,825. The patents are for product-activation technology aimed at preventing unauthorized use or piracy of software.

Z4 Technologies, a private company founded by David Colvin and based in Commerce Township, Michigan, develops digital rights management technology.

None of the companies could be reached for immediate comment.