Before smartphone patents took over the spotlight, everyone's favorite patent troll was Rambus. The technology licensing firm has been using the so-called Barth patents for years to sue tech companies and extract licensing fees as a settlement. After invalidating two of the three Barth patents earlier this year, the U.S. Patent Office has now invalidated the third as well.�
It was the Barth patents that Rambus used to win lawsuits against Nvidia, HP, and more. The technologies described in these patents pertained mostly to memory chip design, and were considered to be Rambus' most valuable IP. Rambus pulled in $312.4 million in revenue last year on the strength of its patent portfolio. That amount is likely to drop in 2012.