Rambus Inc. v. Rea, 731 F.3d 1248

Rambus appeals a Board decision invalidating various claims of U.S. Patent No. 6,260,097 for anticipation and obviousness.
The invention enables dual-edge / double-data-rate DRAM by transferring data on both rising and falling clock edges.
Inagaki discloses half-cycle data transfer using two internal clocks; iAPX discloses data transfer on clock edges but uses full cycles.
The examiner rejected claims as anticipated by Inagaki and obvious in view of iAPX in view of Inagaki; the Board affirmed.
Rambus challenges Board claim construction of “external clock signal” and “write request” and its obviousness analysis, and seeks relief on those grounds.
The court affirms the Board on some points, but vacates and remands for others due to errors in the obviousness analysis.

Issue	Plaintiff's Argument	Defendant's Argument	Held
External clock signal construction	Rambus: external clock must be continuously periodic.	PTO: only periodic during data transfer suffices.	Board proper construction adopted
Write request construction	Rambus: write request requires multiple bits.	PTO: plain language allows single-bit write request.	Board properly construed write request
Obviousness framework	Rambus: Board erred in burden-shifting, used new grounds, and misanalyzed objective evidence.	PTO: combination of iAPX and Inagaki would be obvious; Board can rely on its own fact-finding.	Board errors require vacatur and remand

Ethicon, Inc. v. Quigg, 849 F.2d 1422 (Fed. Cir. 1988) (preponderance of evidence required to show nonpatentability)
In re Jung, 637 F.3d 1356 (Fed. Cir. 2011) (applicant bears burden; examiner must show invalidity)
In re Rambus Inc., 694 F.3d 42 (Fed. Cir. 2012) (claims in expired patents reviewed with district-court-like scope)
Stepan Co., 660 F.3d 1341 (Fed. Cir. 2011) (administrative agency procedure; required fair notice and opportunity to respond)
Kao, 639 F.3d 1057 (Fed. Cir. 2011) (objective evidence must have nexus to claimed invention)