Broadest Reasonable Interpretation Has Limits

The United States Court of Appeals for the Federal Circuit (“the Federal Circuit”) recently put the United States Patent Trial and Appeal Board (“the Board”) on notice that the broadest reasonable interpretation of claims (“BRI”) is not without limits. U.S. Patent No. 6,249,876 ("the ‘876 patent”), owned by the Power Integrations, Inc. (“Power Integrations”), had its claims 1, 17, 18 and 19 rejected in an ex parte reexamination that was appealed to the Board. The Board, relying on an interpretation allowing additional elements to be disposed between “coupled” elements, supported the examiner’s rejection of the claims as anticipated under pre-AIA 35 U.S.C. §102(b). The Federal Circuit reversed the Board’s decision, labeling the claim construction as “unreasonably broad.” IN RE: POWER INTEGATIONS, INC. (Appellant), 2017-1304 (March 19, 2018).

Claim 1 is set forth below to show its use of “coupled”:

A digital frequency jittering circuit for varying the switching frequency of a power supply, comprising:
an oscillator for generating a signal having a switching frequency, the oscillator having a control input for varying the switching frequency;
a digital to analog converter coupled to the control input for varying the switching frequency; and
a counter coupled to the output of the oscillator, the digital to analog converter coupled to the counter, the counter causing the digital to analog converter to adjust the control input and to vary the switching frequency of the power supply.

The Federal Circuit made it clear that it did not agree with the Board’s claim interpretation, citing In re Suitco Surface, Inc., 603 F.3d 1255, 1260 (Fed. Cir. 2010): “The broadest-construction rubric coupled with the term ‘comprising’ does not give the PTO an unfettered license to interpret claims to embrace anything remotely related to the claimed invention.”

The Federal Circuit provided guidance on the interpretation claim language, and found the Board’s support of its claim construction lacking. The Federal Circuit looked for evidence that the Board:

  1. gave reasonable consideration to the language of the claims;
  2. construed the terms of the claims to have meaning;
  3. considered the claims in light of the specification and teachings in the underlying patent as may be supported by:

a. when lacking express definitions, implicit definitions as “. . . may be found in or ascertained by a reading of the patent documents;”

b. evidence of consideration of consistency in specification description, as, for example, between multiple embodiments; and

c. evidence that the board endeavored “to assign a meaning to a disputed claim term that corresponds with . . . how the inventor describes his invention in the specification.”

The Federal Circuit found the Board’s claim interpretation lacking on all of the above. Particularly notable were the Federal Circuit’s observations on:

  • Construing the terms of the claims to have meaning: “The phrase ‘the digital to analog converter [is] coupled to the counter,’ J.A. 817, would be superfluous if, as the board said, it means only that the two components are in the same circuit.”
  • Identifying implicit definitions: The Federal Circuit criticized the board’s interpretation of “coupled” as being so broad as to suggest “that the counter will ‘cause’ the digital to analog converter to adjust the control input and to vary the switching frequency regardless of how insignificantly or indirectly the counter’s output affects the converter’s behavior.”
  • Consistency in the specification description: The Federal Circuit noted the consistent direct coupling of the counter and the digital to analog converter among multiple embodiments described in the patent specification, and that “nothing in the specification suggests that the claims can be stretched to cover a system in which a memory separates the counter and the digital to analog converter and severs the requisite control relationship between them.”
  • Consistent with how the inventor describes his invention: The Federal Circuit looked at the motivation of the inventor, as imputed from the description, and found the Board’s interpretation of “coupled” to be inconsistent with that motivation: “Although the ’876 patent does not expressly exclude a circuit in which a pre-programmed memory is placed between the counter and the digital to analog converter and dictates the converter’s behavior, such an arrangement is inconsistent with both the specification which, as discussed above, emphasizes the need to minimize circuit size. . .”

In light of the deficiencies in the Board’s claim interpretation, the Federal Circuit reversed the rejection of claim 1: “Because the board’s decision affirming the examiner’s rejection of claim 1 was based on an erroneous claim construction and the rejection is not supported under the proper construction, we reverse the rejection of claim 1.” The Federal Circuit extended the reversal to include claims 17, 18 and 19.

Lessons for Practice

  1. When using “coupled” or words of like import, e.g., “connected,” to link elements in claims, consider including affirmative limitations in a dependent claim to moot an interpretation inserting intervening elements.
  2. Be aware that the specification and figures may be used to limit the scope of the claims even without expressly limiting definitions, and consider including a wider variety of embodiments in the detailed description when a broad reading of the claims is desired.

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