Opinion ID: 1041849
Heading Depth: 3
Heading Rank: 1

Heading: “External Clock Signal”

Text: The Board held that the “external clock signal” only requires the clock to be periodic during the data input phases, as opposed to being periodic for all system operations. Rambus, Inc. v. Nvidia Corp., No. 2012-000171 (B.P.A.I. June 11, 2012) (“Board Opinion”). It reached this construction based on the established industry meaning of the term “clock” and the failure of the specification to disclose “a computer clock that runs forever or that cannot be turned off.” Id. at 7-8. Rambus contends that the intrinsic record requires the “external clock signal” to be continuously periodic. It argues that the claims contain this requirement because they recite a “synchronous memory device,” and a clock signal synchronizes all operations in a synchronous device. Rambus contends that, consistent with the claims, the specification only discloses a periodic clock signal. Lastly, Rambus argues that, during prosecution of a related patent, the inventors distinguished the prior art on the basis that it did not teach a periodic clock signal. The PTO counters that the claim language requires only that the memory device receive data “synchronously with respect to a rising edge transition” and the “falling edge transition” of “an external clock signal.” According 6 RAMBUS INC. v. REA to the PTO, this language shows that the “external clock signal” synchronizes data transfer and need not be periodic for all time. We agree with the PTO. The claimed clock signal synchronizes data transfer to the memory device. The claimed method provides a first portion of data “synchronously with respect to a rising edge transition of an external clock signal” and then provides a second portion of data “synchronously with respect to a falling edge transition of the external clock signal.” ’097 patent claim 1. Thus, while the “external clock signal” must be periodic during data transfer, nothing in the claim language requires the signal to be periodic for all time. The specification also shows that the external clock signal is periodic during the transfer of data. Id. fig. 14. Nothing in the specification limits the external clock signal to a clock that is periodic for all time. Nor does the prosecution history upon which Rambus relies require a narrower construction. There, consistent with the plain language of the claims, the inventors explained that the “external clock signal” is “a periodic signal used to orchestrate timing events.” J.A. 2700 n.2 (emphasis omitted). Accordingly, we conclude that the Board properly construed the term “external clock signal.”