PTAB

IPR2025-01219

Marvell Semiconductor Inc v. Credo Technology Group Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Active Ethernet Cable with Fixed, Cable-Independent Equalization
  • Brief Description: The ’252 patent discloses an active Ethernet cable with transceivers in each connector. The technology focuses on using equalization with specific parameter settings to compensate for signal degradation in high-speed data transmission, particularly employing fixed, cable-independent equalization parameters for signals exchanged with a host device.

3. Grounds for Unpatentability

Ground 1: Obviousness over Cornelius and Samaan - Claims 1-4, 6-9, and 11-14 are obvious over Cornelius in view of Samaan.

  • Prior Art Relied Upon: Cornelius (Patent 8,516,238) and Samaan (a 2015 Intel whitepaper titled “High-Speed Serial Bus Repeater Primer”).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Cornelius, an Apple patent, taught the core invention: an active cable with clock and data recovery (CDR) circuits (transceivers) at each end that perform equalization and re-timing. The key disputed limitation, employing "fixed, cable-independent, equalization parameters" for host-side signals (claim 1e), was allegedly disclosed by Cornelius. Cornelius described two approaches for setting equalization parameters: one where they are determined during operation and an alternative where they are "determined by the manufacture[r] and stored as presets." Petitioner contended this preset approach inherently teaches fixed, cable-independent parameters for the host-side paths, as these paths (e.g., short board traces) are independent of the variable characteristics of the main connecting cable. Samaan, an Intel technical paper, was introduced to provide further details on implementing retimer architectures, including specific equalization techniques like TxEQ, CTLE, and DFE, which were common knowledge to a person of ordinary skill in the art (POSITA).
    • Motivation to Combine: A POSITA would combine these references because of the well-known public collaboration between Apple (Cornelius) and Intel (Samaan) on Thunderbolt active cable technology. When implementing the high-level active cable described in Cornelius, a POSITA would naturally consult detailed technical references from its collaborator, Intel, like Samaan, for standard implementation details of retimer and equalization circuits. Market demand for active Ethernet cables provided further motivation to apply these teachings to the Ethernet protocol.
    • Expectation of Success: A POSITA would have a high expectation of success because the combination involved applying known retimer architectures (Samaan) to a known active cable design (Cornelius) to achieve the predictable result of a functional, high-speed active Ethernet cable.

Ground 2: Obviousness over Lugthart and Aronson - Claims 1-14 are obvious over Lugthart in view of Aronson.

  • Prior Art Relied Upon: Lugthart (Patent 9,882,706) and Aronson (Patent 7,445,389).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Lugthart taught a similar active Ethernet cable with transceivers at each end performing CDR, re-modulation, and equalization for both host-side and line-side (cable) paths. Lugthart disclosed using equalization to compensate for "transmission line losses on the host side," which established the use of cable-independent parameters. Aronson was combined to explicitly teach the configuration details for these parameters. Aronson disclosed using "fixed" equalization for host-side PCB traces in both transmit and receive directions, stating "Such equalization could be fixed." For the cable-side path, Aronson taught using adjustable or adaptive parameters to "match the particular length of the characteristics of the copper cabling." The combination of Lugthart’s architecture with Aronson’s specific parameter-setting teachings allegedly rendered all limitations of the challenged claims obvious.
    • Motivation to Combine: A POSITA designing an active cable like Lugthart’s would be motivated to consult a reference like Aronson for implementation details on setting equalization parameters. Aronson provided a known, sensible industry approach: using fixed, preset parameters for the stable host-side environment and customizable parameters for the variable cable-side path. This combination represented a simple choice between a finite number of predictable solutions to improve signal quality and reduce manufacturing complexity and cost.
    • Expectation of Success: Success was expected because applying Aronson's detailed and conventional parameter-setting methods to Lugthart's general active cable architecture was a straightforward implementation of known techniques to achieve the predictable benefits of robust signal integrity.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claims 5 and 10, which add a "per-lane symbol rate in excess of 50 GBd" limitation. This ground relied on the combination of Cornelius and Samaan (Ground 1), further in view of Lugthart, which explicitly taught data rates corresponding to symbol rates in excess of 50 GBd.

4. Key Claim Construction Positions

  • “inbound”/“outbound”: Petitioner argued that the patent defines these terms from the perspective of the cable itself, where "outbound data streams...exit the cable" and "inbound data streams...enter the cable."
  • “each…” (Claim 7): Petitioner contended that the phrase "each employ fixed, cable-independent, equalization parameters" was absent during prosecution and was added due to a clerical error at publication. Therefore, Petitioner argued this language should be considered non-limiting.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-14 of the ’252 patent as unpatentable.