Power Integrations v. Fairchild Semicond

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Power Integrations, Inc. (Delaware)
  • Defendant: Fairchild Semiconductor International, Inc. and Fairchild Semiconductor Corporation (Delaware)
  • Plaintiff’s Counsel: Fish & Richardson P.C.
• Case Identification: 1:04-cv-01371, D. Del., 07/07/2005
• Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendants are incorporated in Delaware and are subject to personal jurisdiction in the district.
• Core Dispute: Plaintiff alleges that Defendant’s pulse width modulation (PWM) integrated circuit devices infringe four patents related to power converter technology, including features for high-voltage transistor design, soft-start functionality, and frequency jittering for EMI reduction.
• Technical Context: The technology relates to integrated circuits used in switched-mode power supplies, which are ubiquitous components for converting AC mains voltage to regulated DC voltage for a wide range of consumer and industrial electronics.
• Key Procedural History: The complaint does not mention any prior litigation, licensing history, or other significant procedural events.

Case Timeline

Date	Event
1987-04-24	’075 Patent Priority Date
1989-03-07	’075 Patent Issue Date
1998-05-18	’851 Patent Priority Date
1998-05-18	’366 Patent Priority Date
1998-11-16	’876 Patent Priority Date
2000-08-22	’851 Patent Issue Date
2001-05-08	’366 Patent Issue Date
2001-06-19	’876 Patent Issue Date
2005-07-07	Complaint Filing Date

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

U.S. Patent No. 6,107,851 - Offline Converter with Integrated Softstart and Frequency Jitter

• Issued: August 22, 2000

The Invention Explained

• Problem Addressed: The patent identifies two key problems in power supply design: (1) high-frequency signals generated by pulse width modulated switches create electromagnetic interference (EMI) that can disrupt other devices, and (2) at startup, an uncontrolled "maximum inrush current" can stress and shorten the life of power supply components (’851 Patent, col. 1:26-55, col. 2:1-18).
• The Patented Solution: The invention proposes a monolithic integrated circuit that solves both problems internally. It incorporates "frequency jitter" functionality, which varies or "smears" the switching frequency to spread the EMI energy over a wider band, reducing its peak value at any single frequency. It also integrates a "soft start" capability that gradually ramps up the switch's duty cycle at power-on, preventing the damaging inrush current (’851 Patent, Abstract; col. 6:1-8:65). Figure 3 illustrates the internal blocks for the frequency variation circuit (405) and soft start circuit (410).
• Technical Importance: Integrating these features onto a single chip reduces the need for external components, lowering the cost, size, and complexity of manufacturing efficient and compliant power supplies (’851 Patent, col. 6:17-24).

Key Claims at a Glance

• The complaint asserts "one or more claims" of the patent (Compl. ¶10). Independent claim 1 is representative and covers:
  • A pulse width modulated switch with a first and second terminal.
  • A switch allowing a signal to be transmitted between the terminals.
  • A "frequency variation circuit" that provides a frequency variation signal.
  • An "oscillator" that provides an oscillation signal whose frequency varies according to the frequency variation signal.
  • A "drive circuit" that provides a drive signal when a maximum duty cycle signal is in a first state and the oscillation signal's magnitude is below a variable threshold.

U.S. Patent No. 6,249,876 - Frequency Jittering Control for Varying the Switching Frequency of a Power Supply

• Issued: June 19, 2001

The Invention Explained

• Problem Addressed: The patent focuses specifically on the problem of EMI generated by the fixed-frequency operation of switched-mode power supplies, which can interfere with radio, television, and other electronic equipment (’876 Patent, col. 1:19-40).
• The Patented Solution: The invention describes a frequency jittering circuit to vary the switching frequency of a power supply's oscillator. One embodiment detailed in the patent uses a digital approach where a counter, clocked by the oscillator's output, drives a digital-to-analog (D/A) converter. The D/A converter's output then modifies a control input to the oscillator, creating a controlled, cyclical variation in its frequency (’876 Patent, Abstract; col. 3:40-4:10). This digital implementation allows for precise, repeatable control over the frequency spreading.
• Technical Importance: This approach provides a structured and integrable method for reducing EMI emissions, helping electronic products meet increasingly strict regulatory standards in a cost-effective manner (’876 Patent, col. 1:41-55).

Key Claims at a Glance

• The complaint asserts "one or more claims" of the patent (Compl. ¶16). Independent claim 1 is representative and covers:
  • A digital frequency jittering circuit.
  • An "oscillator" for generating a signal with a switching frequency, having a control input.
  • A "digital to analog converter" coupled to the control input.
  • A "counter" coupled to the output of the oscillator and to the D/A converter.
  • The counter causes the D/A converter to adjust the control input to vary the switching frequency.

U.S. Patent No. 6,229,366 - Off-Line Converter with Integrated Softstart and Frequency Jitter

• Issued: May 8, 2001
• Technology Synopsis: As a divisional of the application that led to the ’851 Patent, this patent addresses the same technical problems of EMI and startup inrush current in power supplies (’366 Patent, col. 1:12-2:29). The solution is also an integrated circuit that combines frequency jitter and soft-start functionalities to improve performance and reduce external component count (’366 Patent, Abstract).
• Asserted Claims: The complaint asserts "one or more claims" (Compl. ¶22).
• Accused Features: The complaint accuses Defendant's "PWM integrated circuit devices" (Compl. ¶22).

U.S. Patent No. 4,811,075 - High Voltage MOS Transistors

• Issued: March 7, 1989
• Technology Synopsis: This patent addresses the challenge of creating high-voltage MOS transistors that are both efficient and compatible with low-voltage control logic on the same semiconductor chip (’075 Patent, col. 1:7-14, 51-58). The invention describes a specific transistor structure that connects a standard insulated-gate transistor in series with a junction-gate transistor, using an extended drain region and a specialized "top layer" to manage high voltages without sacrificing performance or chip area (’075 Patent, Abstract; col. 2:56-68).
• Asserted Claims: The complaint asserts "one or more claims" (Compl. ¶28).
• Accused Features: The complaint accuses Defendant's "PWM integrated circuit devices" (Compl. ¶28).

III. The Accused Instrumentality

Product Identification

• The complaint identifies the accused instrumentalities as "PWM integrated circuit devices" manufactured, used, imported, and sold by Defendants (Compl. ¶7, 10). No specific product families or part numbers are identified.

Functionality and Market Context

• The accused products are alleged to be integrated circuits used in power conversion applications, such as power supplies for LCD monitors or battery chargers for portable electronics (Compl. ¶7). The core functionality is pulse width modulation (PWM) for regulating power. The complaint does not provide further technical details on the operation of the accused devices or their specific market position.
• No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint makes general allegations of direct, induced, and contributory infringement for each patent-in-suit but does not provide claim charts or a narrative explanation of how any accused device meets any specific claim limitation. The analysis below is therefore based on the high-level allegations presented.

’851 Patent Infringement Allegations

• The complaint does not provide sufficient detail for a claim-chart analysis. It makes a conclusory allegation that Defendants' "PWM integrated circuit devices" infringe one or more claims of the ’851 patent (Compl. ¶10).

Identified Points of Contention

• Technical Question: A primary factual question will be whether discovery reveals that the accused PWM circuits contain both an integrated "soft start" function to control inrush current and an integrated "frequency variation circuit" to implement frequency jitter. The complaint provides no evidence to support the presence of these specific, combined functionalities.
• Scope Question: If such functionalities are found, a potential dispute may arise over whether the specific circuit implementations used by the Defendant fall within the scope of the patent's claims, particularly the functional language used to define the "frequency variation circuit" and the "drive circuit."

’876 Patent Infringement Allegations

• The complaint does not provide sufficient detail for a claim-chart analysis. It makes a conclusory allegation that Defendants' "PWM integrated circuit devices" infringe one or more claims of the ’876 patent (Compl. ¶16).

Identified Points of Contention

• Technical Question: The central question for infringement of claim 1 will be whether the accused devices employ a digital architecture for frequency jittering that includes a "counter" and a "digital to analog converter" that cooperate to vary the oscillator frequency. The complaint offers no facts suggesting that the accused devices utilize this specific implementation.
• Scope Question: If a similar architecture is present, a key legal dispute will concern the construction of the term "digital to analog converter." The question will be whether the accused circuit performs the function of a D/A converter as that term is understood in the patent, or if there is a fundamental operational difference.

V. Key Claim Terms for Construction

Term from ’851 Patent (Claim 1): "frequency variation circuit"

• Context and Importance: This term is central to the infringement analysis for the ’851 Patent. The patentability of the invention rests on the integration of this feature. The dispute will likely focus on whether this term is limited to the specific embodiment shown or covers any circuit that achieves the function of varying the oscillator's frequency.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The claim language itself is functional and does not recite specific components, which may support a construction covering any circuit that "provides a frequency variation signal" (’851 Patent, col. 12:44-45).
  • Evidence for a Narrower Interpretation: The specification describes a specific embodiment in detail, comprising a low-frequency oscillator, comparators, and a latch circuit (e.g., circuit 405 in Fig. 3) (’851 Patent, col. 7:5-8:5). A party could argue the term should be construed as limited to this disclosed structure or its equivalents.

Term from ’876 Patent (Claim 1): "digital to analog converter"

• Context and Importance: Infringement of claim 1 hinges on finding this element in the accused devices. Practitioners may focus on this term because its definition will determine whether a variety of digital or mixed-signal circuits found in modern devices meet this limitation.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The term is not explicitly defined in the specification, which may support giving it a plain and ordinary meaning that is broad and functional in nature.
  • Evidence for a Narrower Interpretation: The specification discloses a specific implementation of the D/A converter comprising a series of binary-weighted current sources switched by MOSFETs (’876 Patent, col. 4:62-5:24; Fig. 1). A defendant could argue that the term should be limited to this structure, where digital inputs directly control weighted analog outputs.

VI. Other Allegations

Indirect Infringement

• The complaint includes conclusory allegations of induced and contributory infringement for all four patents-in-suit (Compl. ¶10, 16, 22, 28). It does not, however, plead any specific facts to support the required elements of knowledge and intent, such as alleging that Defendants' datasheets or user manuals instruct customers to use the devices in an infringing manner.

Willful Infringement

• The complaint alleges that Defendants' infringement has been and continues to be willful, based on "information and belief" (Compl. ¶13, 19, 25, 31). No facts are alleged to support pre-suit knowledge of the patents or egregious conduct that might rise to the level of willfulness.

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

Given the minimal level of factual detail provided in the complaint, the trajectory of this case will be defined by the answers to several fundamental questions that emerge during discovery and claim construction.

• A primary issue will be one of evidentiary proof: Can the Plaintiff develop evidence showing that the accused Fairchild "PWM integrated circuit devices" actually contain the specific circuit architectures and perform the precise functions recited in the asserted claims? For example, discovery will need to establish the existence of an integrated soft-start mechanism (’851 Patent) or a digital counter and D/A converter for frequency jittering (’876 Patent).
• A second core issue will be one of claim scope: Assuming relevant functionalities are found in the accused devices, the case will likely turn on claim construction. Can the functional term "frequency variation circuit" be construed broadly to cover any method of varying frequency, or will it be limited to the specific low-frequency oscillator embodiment disclosed? Similarly, can the term "digital to analog converter" read on the specific mixed-signal circuits used in the accused products?