PTAB

IPR2017-00090

Broadcom Corp v. Progressive Semiconductor Solutions LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Memory Device with Sense Amplifier and Self-Timed Latch
  • Brief Description: The ’208 patent discloses a memory device, such as a static random access memory (SRAM), that includes a sense amplifier for reading data from memory cells, an isolation circuit to decouple the memory cells from the sense amplifier during amplification, and a self-timed storage device (latch) to maintain the amplified data.

3. Grounds for Unpatentability

Ground 1: Claims 1-4, 6-9, and 22-32 are obvious over Reohr and Johnson

  • Prior Art Relied Upon: Reohr (Patent 5,481,500) and Johnson (Patent 5,297,092).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Reohr and Johnson, both directed to memory sense amplifier circuits, collectively disclose all elements of the challenged claims. Reohr was asserted to teach a memory architecture with a sense amplifier, an isolation circuit, and a self-timed latching function that maintains the sense amplifier’s output. Johnson was argued to disclose a similar architecture but with a self-timed latch that is more analogous to the claimed invention because it directly receives the output of the sense amplifier as an input. Petitioner contended that both references teach decoupling the memory cells from the sense amplifier "at about the same time as" asserting the sense enable signal, a key limitation of independent claims 1 and 22.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the teachings of Reohr and Johnson to improve power efficiency. Reohr’s latching mechanism keeps the sense amplifier continuously powered, leading to higher power consumption. Johnson’s design, by contrast, teaches a latch that captures the sense amplifier’s output, allowing the amplifier to be switched off for the remainder of the data cycle. A POSITA would substitute Johnson's power-saving latch design into Reohr's memory architecture to achieve the predictable benefit of reduced power consumption, a well-known goal in integrated circuit design.
    • Expectation of Success: A POSITA would have a high expectation of success in this combination, as it involved replacing one known type of latch circuit with another known, more power-efficient latch circuit within a conventional memory device architecture.

Ground 2: Claims 5 and 10-21 are obvious over Reohr and Johnson in view of Kong

  • Prior Art Relied Upon: Reohr (Patent 5,481,500), Johnson (Patent 5,297,092), and Kong (Patent 6,163,193).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds upon the combination of Reohr and Johnson by adding Kong to address the specific circuit topology of the self-timed storage device recited in dependent claims 5 and 10-21. Petitioner argued that the base combination of Reohr and Johnson taught the overall memory device. Kong was introduced because it explicitly discloses an improved self-timed latch circuit, comprised of cross-coupled inverters and buffer circuits, that matches the specific structure required by these dependent claims. Kong presents its latch as a direct improvement over prior art latches, such as the one disclosed in Johnson.
    • Motivation to Combine: A POSITA, having already combined Reohr and Johnson, would be motivated to further incorporate the teachings of Kong to enhance performance. Kong explicitly teaches that its latch design reduces power consumption and increases operating speed by removing certain feedback connections found in conventional latches like Johnson’s. A POSITA would therefore look to Kong to improve the latch in the base Reohr/Johnson combination to achieve these clearly articulated and desirable advantages.
    • Expectation of Success: Success was expected because the modification involved substituting a known, improved circuit component (Kong's latch) for a functionally equivalent but less efficient component (Johnson's latch) to achieve the predictable results of lower power and higher speed.

4. Key Claim Construction Positions

  • "at about the same time as": Petitioner addressed a construction for this term from a prior district court litigation involving the ’208 patent, which defined it as "after a differential signal is generated but before the sense enable signal is deasserted, occurring within a single clock cycle." While not adopting this construction, Petitioner argued that the timing diagrams and descriptions in both Reohr and Johnson demonstrate a decoupling event that occurs within this narrowly defined window. Petitioner asserted that Johnson's use of a single signal (SAP) to both enable the sense amplifier and trigger isolation meets the relative timing requirement, and that in any event, Reohr discloses separate, independently timed signals for isolation (DEC) and sense enable (SAE) that satisfy the construction.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-32 of the ’208 patent as unpatentable under 35 U.S.C. §103.