Even small differences in operation or design can be sufficient to defeat infringement under the doctrine of equivalents. Here, for example, a parallel architecture that inverted the order of operations for data encoding as compared to the claimed invention, and therefore required fewer transistors but otherwise produced mathematically identical results, was found to constitute a substantial difference in design even when that difference amounted to saving as few as twenty transistors out of the millions found on the chip.
Background / Facts: The patent being asserted here is directed to spread-spectrum encoding techniques for wireless data communication related to several modern wireless communications standards. The claims require randomizing certain data symbols before combining them. It is undisputed that the accused devices randomize the data symbols only after combining them, but the different orderings otherwise produce mathematically identical results.
Issue(s): Whether performing these steps in the reverse order infringes under the doctrine of equivalents because the resulting output of the two orderings is mathematically identical.
Holding(s): No. While recognizing that the idea of equivalency here “has merit,” the court ultimately sided with expert testimony establishing that “even though the different orderings produce mathematically equivalent results, they require structurally different hardware pipelines to implement.” In particular, the ordering affects “the number of multipliers, the number of transistors that are needed on the circuitry,” which “is important, because these circuits, first of all, will take up space on the silicon, on the chip itself, and the more complicated and larger that chip becomes, in general, the more power-hungry it becomes.” While it may be true that “changing the order of operations would save as few as twenty transistors out of the millions found on the chip,” this small difference cannot be discounted as insubstantial per se.