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Court Remands for Additional Evidence on Claim-Construction Issue

April 17, 2002

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Last Month at the Federal Circuit - May 2002

Judges: Clevenger (author), Friedman, and Lourie

In NeoMagic Corp. v. Trident Microsystems, Inc., No. 01-1631 (Fed. Cir. Apr. 17, 2002), the Federal Circuit affirmed-in-part, vacated-in-part, and remand ed a district court’s SJ of noninfringement.

NeoMagic Corporation (“NeoMagic”) is the assignee of U.S. Patent Nos. 5,650,955 (“the ‘955 patent”) and 5,703,806 (“the ‘806 patent”) directed towards a single-chip design for a graphics controller,including the graphics engine and a dynamic random access memory (“DRAM”). To allow the graphics engine and DRAM to coexist on a single chip, the inventors of the ‘955 and ‘806 patents developed a new circuit for logic gates to decouple the voltage sources from the substrate of the graphics controller and designed a reverse-biased n-well to prevent noise. The ‘955 patent concerns the redesigned logic gate that decouples the voltage source from the substrate while the ‘806 patent concerns the reversebiased, n-well invention.

NeoMagic filed suit against Trident Microsystems, Inc. (“Trident”), alleging infringement of the ‘955 and ‘806 patents. The parties disputedthe meaning of the term “coupling” in the ‘955 patent and the terms “power supply” and “negative with respect to” in the ‘806 patent.

For the ‘955 patent, the district court had construed “coupling” to require a voltage potential applied in the substrate that is different from the voltage potential in the logic gates. For the ‘806 patent, the district court had decided that the term “power supply” referred to a source of electrical energy that required at least two power supply lines to deliver a constant voltage supply of power to an electrical circuit. In addition, the district court had construed the term “negative with respect to” to mean an “absolute” negative voltage, i.e., a voltage that is negative with respect to ground.

Based on its construction of the disputed claim terms, the court had entered a SJ of noninfringement for Trident as to all asserted claims of both patents. NeoMagic then appealed.

On appeal, the Federal Circuit affirmed-in-part, vacated-in-part, and remanded. On the ‘955 patent, the Court found that the district court’s construction for “coupling” was correct. The Court found that both proposed claim constructions for “coupling” by NeoMagic and Trident were consistent with the plain language of the claims. However, Trident argued that “coupling” further required components at two different voltages. The Court found that the specification expressly taught a design in which the two components were at different voltages. Accordingly, the Court agreed with Trident and, thus, affirmed the SJ of noninfringement.

As to the ‘806 patent, the district court held that the “BIAS” line of Trident’s device did not provide a constant voltage and, thus, was not a “power supply.” However, no probative evidence was offered to support the “constant voltage” construction for “power supply.” The Federal Circuit held that the district court had improperly construed the claims in reference to the accused device and, in effect, had construed the claims to exclude it. Therefore, the Court remanded for further proceedings to determine whether “power supply” required a constant voltage supply of power.

In addition, the Court vacated the district court’s construction that “negative with respect to” referred to an absolute negative voltage. The Court agreed with NeoMagic that if the inventors had meant to claim an absolute negative voltage, then the words “with respect to” were unnecessary and “negative” alone would have sufficed. Accordingly, the Court found that the plain language of the claims recited a relative voltage rather than an absolute voltage and vacated.