Rambus Inc. has agreed to grant Nvidia Corp. a patent license to use certain memory controllers, bringing to a close more than 18 months of litigation before the U.S. International Trade Commission. Nvidia will pay a one percent royalty for single data rate memory controllers and a two percent royalty for at least eight other types of the digital circuits, the companies said in a joint statement Friday. Further details of the agreement, which went into effect Thursday, were not disclosed. Rambus is represented by Finnegan.