IP Law Daily Erroneous construction of microprocessor clock claim vacated and remanded
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Friday, March 3, 2017

Erroneous construction of microprocessor clock claim vacated and remanded

A stipulated judgment in favor of mobile device makers accused of infringing a patent for a microprocessor with two independent clocks has been vacated by the U.S. Court of Appeals for the Federal Circuit because the stipulated judgment was based on the district court’s erroneous construction of a key claim term. Although the appellate court said that its minor modification to the district court’s construction likely would not affect the outcome, the appellate court vacated the district court’s construction and remanded for further proceedings (Technology Properties Limited LLC v. Huawei Technologies Co., Ltd., March 3, 2017, Moore, K.).

The patent-in-suit, U.S. Patent No. 5,809,336 ("the ’336 patent"), disclosed a microprocessor with two independent clocks—a variable frequency system clock connected to the central processing unit (CPU) and a fixed-frequency clock connected to the input/output (I/O) interface. The ’336 patent taught improving microprocessor performance by decoupling the CPU and I/O clocks. The variable-speed CPU clock—a ring oscillator—was fabricated on the same silicon substrate as the rest of the microprocessor, including the CPU itself. Because the CPU and CPU clock were fabricated on the same silicon substrate, they reacted similarly to external stressors, allowing the maximum processing speed of the CPU to track the oscillating frequency of its clock. The I/O clock—a quartz crystal—was located off-chip, which allowed the microprocessor to achieve optimum performance of each clock.

The patent holders brought five separate lawsuits against several mobile device manufacturers, including Samsung, LG, and Nintendo. After claim construction, the parties stipulated to noninfringement based on the district court’s construction of a single claim term. Claim 6 of the ’336 patent—which was a representative claim—required "an entire oscillator disposed upon said integrated circuit substrate," which referred to the variable-frequency CPU clock. The district court construed the term to mean "an oscillator located entirely on the same semiconductor substrate as the central processing unit that does not require a control signal and whose frequency is not fixed by any external crystal" (emphasis added). The parties agreed to the first half of the construction but disputed the emphasized portion. The device makers contended that the second half of the construction was proper because the patentee disclaimed certain claim scope during prosecution to overcome rejections based on U.S. Patent Nos. 4,503,500 ("Magar") and 4,670,837 ("Sheets"). Specifically, the device makers argued that the construction "whose frequency is not fixed by any external crystal" was mandated by the patentee’s disclaiming statements relating to Magar, and the construction "that does not require a control signal" was required by disclaiming statements relating to Sheets.

The Federal Circuit affirmed the district court’s construction that an "entire oscillator" is one "whose frequency is not fixed by any external crystal," rejecting the patent holders’ argument that the district court erred by limiting an "entire oscillator" to one "whose frequency is not fixed by any external crystal" and that the limitations of the ’336 patent were distinct from the teachings of Magar. Even if the patentee disclaimed more than was necessary to overcome the examiner’s rejection based on Magar, the scope of surrender was not limited to what was absolutely necessary to avoid a prior art reference; patentees may surrender more than necessary. In such cases, the court held patentees to the actual arguments made, not the arguments that could have been made. Accordingly, the district court’s narrowing construction based on Magar—"whose frequency is not fixed by any external crystal"—properly encapsulated the patentee’s disclaiming statements, the Federal Circuit said.

The district court erred, however, by limiting an "entire oscillator" to one "that does not require a control signal." The Federal Circuit held that the term was properly construed as one "that does not require a command input to change the clock frequency." The district court erred by holding that the patentee disclaimed any use of a command signal by the entire oscillator. Rather, the patentee disclaimed a particular use of a command signal—using a command signal to change the clock frequency. The patentee argued during prosecution that Sheets was distinguishable from the ’336 patent claims because Sheets required "a command input ... to change the clock speed" and that Sheets’ system "for providing clock control signals to an external clock" was "unrelated" to the claimed invention. The patentee argued that its claims did not "rely upon [the] provision of frequency control information to an external clock" taught in Sheets because all claimed components were located on the same substrate. None of the patentee’s statements disclaimed an entire oscillator receiving a command input for any purpose, the Federal Circuit said.

The Federal Circuit opined that this minor adjustment to the claim construction probably would not affect the outcome of the case, since the parties stipulated to noninfringement under the district court’s construction. However, the court decided that the proper thing to do was vacate and remand.

The case is Nos. 2016-1306, 2016-1307, 2016-1309, 2016-1310, and 2016-1311.

Attorneys: Thomas Cecil (Nelson Bumgardner PC) for Technology Properties Limited LLC, Phoenix Digital Solutions LLC, and Patriot Scientific Corp. Mark D. Fowler (DLA Piper US LLP) for Huawei Technologies Co., Ltd., Futurewei Technologies, Inc., Huawei Device Co., Ltd., Huawei Device USA Inc., Huawei Technologies USA Inc., ZTE Corp., ZTE USA, Inc., Samsung Electronics Co., Ltd., Samsung Electronics America, Inc., LG Electronics, Inc., LG Electronics U.S.A., Inc., Nintendo Co., Ltd., and Nintendo of America Inc.

Companies: Technology Properties Limited LLC; Phoenix Digital Solutions LLC; Patriot Scientific Corp.; Huawei Technologies Co., Ltd.; Futurewei Technologies, Inc.; Huawei Device Co., Ltd.; Huawei Device USA Inc.; Huawei Technologies USA Inc.; ZTE Corp.; ZTE USA, Inc.; Samsung Electronics Co., Ltd.; Samsung Electronics America, Inc.; LG Electronics, Inc.; LG Electronics U.S.A., Inc.; Nintendo Co., Ltd.; Nintendo of America Inc.

MainStory: TopStory Patent FedCirNews

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