Aido LLC v. On Semiconductor Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Aido LLC (Texas)
  • Defendant: ON Semiconductor Corporation (Delaware)
  • Plaintiff’s Counsel: Stamoulis & Weinblatt LLC
• Case Identification: 1:19-cv-01110, D. Del., 06/17/2019
• Venue Allegations: Venue is alleged to be proper based on Defendant's incorporation in Delaware and its conduct of substantial business in the district.
• Core Dispute: Plaintiff alleges that Defendant’s Class-D Audio Power Amplifier infringes a patent related to reducing signal distortion in switching amplifiers.
• Technical Context: The technology concerns Class-D switching amplifiers, which are widely used in consumer electronics for their high power efficiency, particularly in portable and battery-powered audio devices.
• Key Procedural History: The complaint does not specify any prior litigation, licensing history, or other procedural events.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,937,090 - "Charge Injection Reduction Technique in Single and Multi-Reference Switching Amplifiers"

• Patent Identification: U.S. Patent No. 6937090, "Charge Injection Reduction Technique in Single and Multi-Reference Switching Amplifiers," issued August 30, 2005 (’090 Patent).

The Invention Explained

• Problem Addressed: The patent describes a "parasitic effect" in high-accuracy switching amplifiers where the control signal used to turn a switch on or off "inject[s] a portion of the control signal" into the amplifier's output (ʼ090 Patent, col. 1:22-26). This unwanted charge injection creates distortion, which is particularly problematic in bipolar designs like audio amplifiers (ʼ090 Patent, col. 1:30-34).
• The Patented Solution: The invention proposes a method of "adding a minimum pulse width" to the switching signals for both outputs of a differential pair (ʼ090 Patent, col. 1:36-38). By adding this minimum pulse simultaneously and with the same polarity to both sides, the resulting charge injection error becomes a "common-mode" signal, which is effectively canceled or "nulled" by the differential nature of the output, leading to a more accurate final signal (ʼ090 Patent, col. 1:38-44).
• Technical Importance: This technique aims to nullify an "undesired switching device deficiency," thereby improving the accuracy and reducing distortion in pulse-width-modulated (PWM) amplifiers without requiring more complex or expensive components (ʼ090 Patent, col. 1:33-34).

Key Claims at a Glance

• The complaint asserts infringement of at least independent claim 1 (Compl. ¶10).
• Claim 1 recites the following essential elements for an improvement in a switching amplifier:
  • adding a minimum pulse width of the same polarity to a pair of switching devices simultaneously, one on either side of the load,
  • to null the common-mode output presented to the load.
• The complaint does not explicitly reserve the right to assert dependent claims.

III. The Accused Instrumentality

Product Identification

• The NCP2820 Series 2.65 W Filterless Class-D Audio Power Amplifier ("Accused Device") (Compl. ¶10).

Functionality and Market Context

• The complaint describes the Accused Device as a switching amplifier that includes an H-bridge CMOS power stage controlled by a pulse width modulator (Compl. ¶12). It allegedly employs a "PWM modulation scheme" where each output switches between 0 volts and the supply voltage (Compl. ¶13). A "Typical Application" diagram from the product's datasheet is included in the complaint, showing the amplifier's architecture with differential inputs and outputs connected to a load. (Compl. p. 3, Fig. 1).
• The complaint highlights a "Fully Differential Design" as a key feature, which it alleges "eliminates the need of two input coupling capacitor" and causes the current through the load to be zero for most of the switching period (Compl. ¶14). This suggests the product is marketed for applications where component count and board space are considerations, such as in portable electronics.

IV. Analysis of Infringement Allegations

’090 Patent Infringement Allegations

Identified Points of Contention

• Scope Question: A primary point of contention may be whether the accused product's behavior—where its differential outputs (OUTM and OUTP) become "in phase" when the input signal is zero (Compl. p. 4, Fig. 35)—constitutes "adding a minimum pulse width" as required by the claim. The defense may argue its technique is a standard PWM idle state, not the specific addition of a pulse for error correction as described in the patent.
• Technical Question: The infringement theory hinges on equating the accused product's "fully differential design" that results in "0 ampere" of current through the load with the claimed function of "null[ing] the common-mode output" (Compl. ¶14). A key question is whether the accused product's zero-current idle state performs the specific function taught by the patent: canceling a "parasitic" error term caused by charge injection (ʼ090 Patent, col. 1:19-34). The court may need to determine if there is a functional mismatch between nulling an error component (the patent's focus) and nulling the output current (the complaint's allegation).

V. Key Claim Terms for Construction

The Term: "adding a minimum pulse width"

• Context and Importance: The plaintiff’s infringement theory equates the phrase "adding a minimum pulse width" with the accused device's PWM scheme (Compl. ¶13). The viability of the infringement claim depends on whether the accused device's standard operation can be characterized as "adding" such a pulse.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent does not appear to provide an explicit definition for the full phrase, which may support an argument that the term should be given its plain and ordinary meaning to a person of skill in the art of amplifier design.
  • Evidence for a Narrower Interpretation: The specification consistently frames the "minimum pulse width" as part of a solution to the specific problem of "charge injected principally from control signals" (ʼ090 Patent, col. 2:14-15). This context suggests the "adding" step is a deliberate act to counteract a known distortion artifact, not merely an inherent feature of a standard PWM idle state.

The Term: "null the common-mode output"

• Context and Importance: The complaint alleges that achieving "0 ampere" of current through the load is equivalent to this limitation (Compl. ¶14). The construction of this term is critical to determining if the accused product's functionality meets this claim element.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: A party could argue that any method resulting in a net-zero common-mode signal at the load satisfies this limitation, regardless of the underlying mechanism.
  • Evidence for a Narrower Interpretation: The Summary of the Invention states the goal is to inject a "similar error term into both sides of a differential output, thus presenting it as a null common-mode output" (ʼ090 Patent, col. 1:39-42). This language suggests that "nulling the common-mode output" refers specifically to the cancellation of this intentionally introduced, symmetrical error signal, not simply achieving a quiescent or zero-current state in the load.

VI. Other Allegations

Indirect Infringement

• The complaint does not allege indirect infringement. The allegations are limited to direct infringement under 35 U.S.C. § 271(a) (Compl. ¶10).

Willful Infringement

• The complaint does not contain an explicit allegation of willful infringement. It does, however, request a declaration that the case is "exceptional" under 35 U.S.C. § 285 in its prayer for relief (Compl., Prayer for Relief ¶C).

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this dispute will likely depend on the court’s interpretation of key claim terms in light of the patent's specific teachings and the accused product's actual operation. The central questions are:

• A core issue will be one of definitional scope: can the phrase "adding a minimum pulse width," which the patent presents as a solution to charge injection distortion, be construed to read on the accused amplifier's documented method of creating an in-phase, zero-current idle state?
• A key evidentiary question will be one of functional purpose: does the accused product's "Fully Differential Design," aimed at eliminating coupling capacitors and achieving a filterless output, perform the specific function of "null[ing] the common-mode output" in the same way as the patented invention, which is described as a technique to cancel out parasitic error signals?