Home Third Critical Rambus Patent Invalidated, Nvidia Vindicated

Third Critical Rambus Patent Invalidated, Nvidia Vindicated

U.S. Patent # 6,591,353, “Protocol for Communication with Dynamic Memory,” tends to refer to a “memory device.” The innovation with respect to this device appeared to be the introduction of a synchronous clock. That way, time-multiplexed transfers could take place in a regulated fashion.

But as USPTO documents published today show, the appeals judges found that two existing patents cited by Nvidia qualify as prior art, and moreover, that the teachings demonstrated by those older patents would be inspiration enough for a skilled artisan to apply the teachings to improving synchronous memory the way Nvidia appears to have done.

In their decision, the judges refer to the patent concepts by the names of their inventors – “Hayes” for the one under contention, “Bennett” for the prior art. Citing directly from the decision:

The Examiner agrees that Hayes discloses a memory device and anticipates claim 1, but maintains that including all the RAM control logic into each Hayes DRAM chip would not have been obvious… But dependent claim 2 recites sampling data synchronously and does not require all the RAM control logic to be integrated into each chip. NVIDIA points out that the term “memory device” in these claims is not limited to a single chip, but even if they are, NVIDIA persuasively shows the obviousness of creating a single chip… The claim 2 memory device, whether as a chip or a broader device, requires strobe functionality which Hayes teaches and synchronization which Bennett teaches according to this record. As NVIDIA persuasively explains, Hayes describes time-multiplexed clock data transfers between a master and slave during different clock cycles, and Bennett teaches benefits to providing a synchronized interface in a memory device using an external clock. The Examiner does not appear to disagree with these findings… NVIDIA also relies on Mr. Parris [an expert witness] who testifies that ordinarily skilled artisans were shifting from asynchronous to synchronous operations to increase speed… Based on this record, NVIDIA shows that it would have been obvious in view of Bennett to implement certain control logic, including a synchronous logic interface, into the memory device of Hayes.

This week’s loss is the latest in a string of bad luck for Rambus, that comes on the heels of what had been an upward trend for a company whose reputation was pretty much created in the courtroom. The uptick began four years ago, when a Federal Trade Commission ruling was overturned. That ruling had found Rambus was withholding critical implementation plans for its memory standards from the JEDEC standards agency, and had sent a signal to the industry that Rambus was unfairly trying to manipulate standards to its own advantage. The overturning of that ruling was the beginning of what had been a glorious resurrection of Rambus’ respect.

But perhaps buoyed too much by the outcome, Rambus then tried to hold the same manufacturers that first accused it of unfair standards manipulation – Hynix Semiconductor and Micron technologies – responsible for essentially the same conduct. The court didn’t buy that argument either, ruling in favor of Hynix and Micron two months ago.

Suddenly, Rambus had resumed its former public image of pursuing greater revenues through litigation. With only three of six patents remaining valid in its case against Nvidia and five others, Rambus may not be able to hold on to even that. Today, Rambus’ stock price hit what memory engineers would call a “low state,” losing another 13% in NASDAQ trading today after already having lost over half its value last November in the wake of the Hynix/Micron decision.

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