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Vicor Corp. v. SynQor, Inc.

United States Court of Appeals, Federal Circuit

August 30, 2017

VICOR CORPORATION, Appellant
v.
SYNQOR, INC., Appellee SYNQOR, INC., Appellant
v.
VICOR CORPORATION, Appellee

         Appeal from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 95/001, 861, 95/001, 637.

          Matthew A. Smith, Smith Baluch LLP, Washington, DC, argued for Vicor Corporation. Also represented by ANDREW T. D'Amico, Jr., Vicor Corporation, Andover, MA; Lawrence K. Kolodney, Fish & Richardson, PC, Boston, MA.

          Thomas D. Rein, Sidley Austin LLP, Chicago, IL, argued for SynQor, Inc. Also represented by CONSTANTINE L. Trela, Jr., Bryan C. Mulder.

          Before LOURIE, TARANTO, and Chen, Circuit Judges.

          CHEN, CIRCUIT JUDGE.

         SynQor, Inc. (SynQor) owns several patents directed to a particular architecture for direct current-to-direct current (DC-DC) power converters, including U.S. Patent Nos. 8, 023, 290 (the '290 patent) and 7, 272, 021 (the '021 patent) (hereinafter, we refer to the '290 and '021 patents collectively as the SynQor Patents). Vicor Corporation (Vicor) requested, and the Patent and Trademark Office (PTO) granted, inter partes reexaminations of the SynQor Patents. The reexaminations were ultimately decided by the Patent Trial and Appeal Board (Board), which was confronted with many proposed rejections and highly technical competing arguments. Vicor appeals the Board's decision in the '290 patent's reexamination holding that certain claims are patentable over prior art combinations proposed by Vicor. SynQor, for its part, appeals the Board's decision in the '021 patent's reexamination holding that certain claims in that patent are unpatentable as anticipated or obvious.

         We address these two appeals in a single opinion because the two patents claim very similar inventions, and their respective reexaminations share common patentability issues. Both reexaminations were decided by the same panel of administrative patent judges. The panel's decision in the '290's reexamination issued on the same date as the panel's decision on rehearing in the '021's reexamination. Despite sharing a common panel and having opinions issued on the same date, the decisions in the respective reexaminations contain inconsistent findings on identical issues and on essentially the same record. We affirm in part, vacate in part, and remand the Board's decisions in both reexaminations.[1]

         Background

         I. DC-DC Power Converters

         The SynQor Patents claim systems and methods for DC-DC power conversion. See generally '290 patent col. 17 1. 9-col. 18 1. 35; '021 patent col. 6 1. 21-col. 8 1. 60. Direct current (DC) flows in only one direction, whereas alternating current (AC) periodically reverses direction. AC power supplied from a utility is converted to DC by a "front end converter." A DC-DC converter receives the DC output of a front end converter and transforms it into one or more lower DC voltages.

         The DC-DC converters at issue in this appeal are designed to drive logic circuitry in large computer and telecommunications systems that typically require a number of different power voltages. The claimed converters perform two general operations in sequence: "isolation" and "regulation." Isolation converts a DC input into AC, reduces the AC voltage using a transformer, and converts AC back to DC at a voltage level lower than the DC input. Regulation then restricts that isolated output down to a DC voltage appropriate for driving logic circuity.

         A. Isolation

         Isolation enhances safety and prevents unwanted noise by using a transformer to lower voltage without using wires connecting inputs and outputs. A transformer comprises "primary" and "secondary" windings, such as coiled wires. The transformer's input is connected to the primary winding, which transfers electrical energy to the secondary winding via magnetic fields. The transformer's output from the secondary winding is a fraction, or multiple, of the transformer's input determined by the ratio of turns in the respective primary and secondary windings. For example, a transformer with a primary winding that has twice as many turns as the secondary winding will have an output voltage that is half of its input.

         Isolation circuitry converts the secondary winding's AC output to DC using rectifiers. The SynQor Patents' claims all require use of "controlled" rectifiers, which use control signals and circuitry to reverse or prevent the flow of current in one direction. Embodiments of the SynQor Patents' inventions use a particular type of pre-existing controlled rectifier known as a "synchronous" rectifier, which uses a waveform of current flow across one of the transformer's windings to control switching circuitry that generates a DC output.

         B. Regulation

         Regulation circuitry receives an isolated DC output and regulates it down to appropriate voltage(s) to drive logic circuitry. Regulation was known to be implemented using at least two types of regulators: "switching" regulators and "linear" regulators. Switching regulators include a transistor-implemented switch, which turns on and off in response to one or more parameters sensed in the circuit to maintain output voltage at a predefined value. Linear regulators regulate an output by varying the resistance of the regulator.

         C. Prior Art DC-DC Power Converters

         Prior art power architectures for large computer and telecommunications systems used DC-DC power converters that integrated isolation and regulation circuitry in each individual converter. The presence of isolation circuitry in every converter took up valuable space on circuit boards where the converters were located, which could have been used for additional microprocessors, memory, or logic circuitry.

         II. SynQor's Patents

         A. SynQor's Asserted Improvement over the Prior Art

         The SynQor Patents claim to improve prior art systems by separating the isolation and regulation functionality of DC-DC converters into two steps and using a single isolation stage to drive multiple regulation stages. See '290 patent Fig. 1, col. 4 U. 40-54; '021 patent Fig. 5, col. 5 11. 6-12. The single isolation stage drives an "intermediate bus" that is fed to multiple on-board regulator components. See -2288 J.A. 1117-19.[2] The regulators can be smaller, less expensive, and more efficient compared to regulators used in on-board, integrated isolating/regulating converters. SynQor portrays this separation of isolation and regulation stages as the key invention of the SynQor Patents and "a revolutionary new power architecture" developed by SynQor's CEO-Dr. Martin Schlecht-who is the sole named inventor on the SynQor Patents. -2288 Open. Br. at 2. According to SynQor, the new two-stage architecture, which became known as "Intermediate Bus Architecture" (IBA), was "hailed in the field, copied by SynQor's competitors, and widely adopted by the industry." Id.

         B. Disputed Claims of the SynQor Patents

         The SynQor Patents' claims tailor their coverage of IBAs general schema by including limitations that require specific circuit features. First, all of the claims require separate isolation and regulation stages comprising (1) a "non-regulating" isolation stage and (2) a plurality of "non-isolating" regulation stages. See generally '290 patent col. 17 1. 9-col. 18 1. 35; '021 patent col. 6 1. 21-col. 8 1. 60.

         Second, all claims of the '290 patent and claims 49-50 of the '021 patent require the regulation to be done by switching regulators. See generally '290 patent col. 17 1. 9-col. 18 1. 35; -2288 J.A. 115 (reciting claims 49-50 of the '021 patent, added during reexamination). SynQor argues that switching regulators provide more efficient regulation than linear regulators used in prior art converters.

         Third, for the non-regulating isolation stage, all claims of the '021 patent require "substantially uninterrupted flow of power" through a transformer's "primary and secondary winding circuits." See generally '021 patent col. 6 1. 21-col. 8 1. 60. The '021 patent's specification describes circuitry that regulates the flow of power across the primary and secondary windings by setting a "duty cycle" for periodically reversing the directional flow of current across the primary winding. See id. col. 3 1. 62-col. 4 1. 18. The '021 patent explains that power is always flowing through the isolation stage, except during "brief switch transitions." '021 patent col. 4 11. 8-11.

         Finally, both patents include dependent claims that limit input and output voltages to ranges appropriate for converters that receive DC power from a front end converter and output DC power to drive logic circuitry. See, e.g., '290 patent col. 18 11. 7-9 (claim 7); '021 patent col. 7 11. 40-42 (claim 25). SynQor argues that restricting circuit operation to these voltage ranges distinguishes prior art power systems that were not designed for powering telecommunications or computer systems.

         The sole independent claim of the '290 patent, claim 1, covers an IBA converter implemented with switching regulators:

A DC-DC power converter system providing plural regulated DC outputs, each having a regulated voltage, comprising:
a DC input;
a non-regulating isolating converter comprising:
a primary transformer winding circuit having at least one primary winding that receives power from the DC input; and
a secondary transformer winding circuit having at least one secondary winding coupled to the at least one primary winding and having plural controlled rectifiers, each having a parallel uncontrolled rectifier and each in circuit with a secondary winding, each controlled rectifier being turned on and off in synchronization with a voltage waveform of the at least one primary winding to provide a non-regulated, isolated DC output; and plural non-isolating switching regulators, each receiving power from the non-regulated, isolated DC output of the non-regulating isolating converter and each providing one of the regulated DC outputs having a regulated voltage.

         '290 patent col. 1711. 9-30 (emphasis added).

         Claim 7 of the '290 patent is exemplary of the dependent claims in the SynQor Patents that specify input/output voltage ranges for telecommunications or computer systems:

A power converter system as claimed in claim 1 wherein each regulated voltage of each of the regulated DC outputs is of a voltage level to drive logic circuitry.

'290 patent col. 18 11. 7-9 (emphasis added).

         Claim 1 of the '021 patent is very similar to claim 1 of the '290 patent, but includes the "substantially uninterrupted flow of power" limitation present in all claims of the'021 patent:

A power converter system comprising:
a normally non-regulating isolation stage ...

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