DCT
1:08-cv-00309
Power Integrations Inc v. Fairchild Semiconductor Intl Inc
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Power Integrations, Inc. (Delaware)
- Defendant: Fairchild Semiconductor International, Inc. (Delaware), Fairchild Semiconductor Corporation (Delaware), and System General Corporation (Taiwan)
- Plaintiff’s Counsel: Fish & Richardson P.C.
- Case Identification: 1:08-cv-00309, D. Del., 05/23/2008
- Venue Allegations: Venue is alleged to be proper based on Defendants being subject to personal jurisdiction within the District of Delaware.
- Core Dispute: Plaintiff alleges that Defendant’s pulse width modulation (PWM) controller integrated circuits infringe patents related to power supply regulation, specifically technologies for reducing electromagnetic interference (EMI) via frequency jittering and for managing power delivery.
- Technical Context: The technology at issue involves integrated circuits for power converters, which are ubiquitous components in electronic devices such as power adapters, battery chargers, and monitors, where efficiency and compliance with EMI standards are critical market drivers.
- Key Procedural History: The complaint is the initial pleading in this matter and does not reference any prior litigation, licensing history, or administrative proceedings related to the patents-in-suit.
Case Timeline
| Date | Event |
|---|---|
| 1998-05-18 | U.S. Patent No. 6,107,851 Priority Date |
| 1998-11-16 | U.S. Patent No. 6,249,876 Priority Date |
| 2000-08-22 | U.S. Patent No. 6,107,851 Issued |
| 2001-06-19 | U.S. Patent No. 6,249,876 Issued |
| 2001-09-27 | U.S. Patent No. 7,110,270 Priority Date |
| 2006-09-19 | U.S. Patent No. 7,110,270 Issued |
| 2008-05-23 | Complaint Filed |
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’s background describes two problems with conventional pulse width modulated (PWM) power supplies: 1) they generate high-frequency signals that create Electromagnetic Interference (EMI), which is subject to government regulation; and 2) they are subject to a large "inrush current" at startup, which stresses components and reduces the device's lifespan (ʼ851 Patent, col. 1:21-40; col. 2:1-17).
- The Patented Solution: The invention describes a single integrated circuit that addresses both issues. To combat EMI, it employs "frequency jitter," which intentionally varies the switch's operating frequency to spread the interference energy over a wider spectrum, reducing its peak value ('851 Patent, col. 3:10-25). To manage startup stress, it integrates a "soft-start" function that limits the switch's duty cycle for a predetermined time, thereby reducing the inrush current ('851 Patent, col. 6:1-10). Figure 3 illustrates this combination, with a low-frequency oscillator (405) generating a frequency variation signal and a soft-start circuit (410) controlling the initial power-up sequence.
- Technical Importance: By integrating these EMI and startup protection features onto a single monolithic device, the invention aimed to reduce the number of external components, overall cost, and design complexity for power supplies ('851 Patent, col. 6:17-21).
Key Claims at a Glance
- The complaint generally alleges infringement of "one or more claims of the ’851 patent" without specifying any (Compl. ¶13). Independent claim 1 is representative of the core invention.
- Independent Claim 1:
- a pulse width modulated switch comprising: a first terminal; a second terminal;
- a switch comprising a control input, said switch allowing a signal to be transmitted between said first terminal and said second terminal according to a drive signal provided at said control input;
- a frequency variation circuit that provides a frequency variation signal;
- an oscillator that provides an oscillation signal having a frequency range, said frequency of said oscillation signal varying within said frequency range according to said frequency variation signal, said oscillator further providing a maximum duty cycle signal comprising a first state and a second state; and
- a drive circuit that provides said drive signal when said maximum duty cycle signal is in said first state and a magnitude of said oscillation signal is below a variable threshold level.
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 addresses the challenge of reducing EMI in switched-mode power supplies to meet regulatory compliance limits, noting that conventional solutions like adding filters increase cost and size (’876 Patent, col. 1:20-56).
- The Patented Solution: The invention discloses a method for "jittering" a power supply's switching frequency using a digital feedback mechanism. An oscillator's output clocks a counter, which in turn provides a digital input to a digital-to-analog (D/A) converter. The D/A converter's analog output is then fed back to the oscillator's control input, systematically varying its frequency in a controlled, cyclical manner ('876 Patent, Abstract). The relationship between the oscillator (110), counter (140), and D/A converter (150) is illustrated in Figure 1.
- Technical Importance: This digital approach to frequency jittering allows for precise and repeatable control over the EMI spectrum, potentially offering more consistent manufacturing outcomes and easier integration compared to purely analog solutions ('876 Patent, col. 4:1-10).
Key Claims at a Glance
- The complaint broadly alleges infringement of "one or more claims of the ’876 patent" (Compl. ¶19). Independent claim 1 is representative.
- Independent Claim 1:
- 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 and to the digital to analog converter, the counter causing the digital to analog converter to adjust the control input and to vary the switching frequency.
U.S. Patent No. 7,110,270 - Method and Apparatus for Maintaining a Constant Load Current with Line Voltage in a Switch Mode Power Supply, issued September 19, 2006
- Patent Identification: U.S. Patent No. 7,110,270, "Method and Apparatus for Maintaining a Constant Load Current with Line Voltage in a Switch Mode Power Supply," issued September 19, 2006 (Compl. ¶24).
- Technology Synopsis: This patent addresses the problem of maintaining a constant output current from a power supply despite variations in input line voltage, a key requirement for applications like battery chargers. The invention achieves this by dynamically varying the regulator's internal current limit threshold during each switching cycle, increasing it as a function of elapsed time to compensate for the effects of higher or lower input voltages (’270 Patent, Abstract; col. 3:12-20).
- Asserted Claims: The complaint alleges infringement of "one or more claims of the '270 patent" (Compl. ¶25). Independent claim 1 is a representative claim.
- Accused Features: The complaint accuses Defendants' PWM integrated circuit devices of incorporating the patented technology for maintaining constant load current (Compl. ¶10, ¶25).
III. The Accused Instrumentality
Product Identification
- The complaint identifies the accused instrumentalities as "pulse width modulation ('PWM') controller integrated circuit devices" (Compl. ¶10).
Functionality and Market Context
- The complaint alleges these devices are intended for use in power conversion applications, including "LCD monitor power supplies, off-line power supplies or battery chargers for portable electronics" (Compl. ¶10). Plaintiff alleges that Defendants manufacture, sell, and import these integrated circuits, and also encourage and support third parties in selling products that incorporate these devices (Compl. ¶10). The complaint does not provide specific product model numbers or technical documentation for the accused devices. No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
The complaint provides a general allegation that the accused PWM controller integrated circuits are "covered by one or more claims" of each patent-in-suit but does not include specific factual allegations, element-by-element analysis, or claim charts. The infringement theory must be inferred from the broad identification of the accused products.
’851 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a pulse width modulated switch comprising: a first terminal; a second terminal; a switch comprising a control input... | The complaint alleges that Defendants' PWM controller integrated circuit devices are or contain a pulse width modulated switch with the claimed structural elements. | ¶10, ¶13 | col. 11:15-26 |
| a frequency variation circuit that provides a frequency variation signal; | The complaint alleges that Defendants' devices contain a circuit that generates a frequency variation signal for EMI reduction. | ¶10, ¶13 | col. 11:27-29 |
| an oscillator that provides an oscillation signal having a frequency... varying within said frequency range according to said frequency variation signal... | The complaint alleges that an oscillator within Defendants' devices varies its frequency in response to the alleged frequency variation signal. | ¶10, ¶13 | col. 11:30-38 |
| a drive circuit that provides said drive signal when said maximum duty cycle signal is in said first state and a magnitude of said oscillation signal is below a variable threshold level. | The complaint alleges that a drive circuit within Defendants' devices provides the drive signal to the switch under the conditions required by the claim. | ¶10, ¶13 | col. 11:39-44 |
’876 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| an oscillator for generating a signal having a switching frequency, the oscillator having a control input for varying the switching frequency; | The complaint alleges that Defendants' PWM controller integrated circuit devices contain an oscillator with a control input for frequency modulation. | ¶10, ¶19 | col. 8:46-49 |
| a digital to analog converter coupled to the control input for varying the switching frequency; | The complaint alleges that Defendants' devices contain a circuit that functions as a digital to analog converter coupled to the oscillator's control input. | ¶10, ¶19 | col. 8:50-52 |
| a counter coupled to the output of the oscillator and to the digital to analog converter, the counter causing the digital to analog converter to adjust the control input... | The complaint alleges that Defendants' devices use a counter, clocked by the oscillator, to drive the D/A converter and thereby vary the switching frequency. | ¶10, ¶19 | col. 8:53-57 |
Identified Points of Contention
- Evidentiary Questions: The complaint's lack of technical detail raises the question of what evidence Plaintiff will produce to demonstrate that the accused PWM controllers contain the specific circuit architectures recited in the claims. The central dispute will likely involve reverse engineering and circuit analysis of the accused products.
- Technical Questions: A primary technical question is whether the accused devices achieve frequency jittering using the specific mechanisms claimed in either the ’851 or ’876 patents. For instance, does the accused method rely on an analog "frequency variation circuit" ('851 patent) or a digitally-controlled "counter" and "D/A converter" feedback loop ('876 patent), or does it employ a different, non-infringing technique? The complaint does not provide sufficient detail for analysis of this point.
V. Key Claim Terms for Construction
For the ’851 Patent
- The Term: "frequency variation circuit"
- Context and Importance: This term is central to the invention of the ’851 patent. The outcome of the infringement analysis may depend on whether this term is construed broadly to cover any circuit that generates a signal to vary frequency, or narrowly to the specific embodiment described.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim language itself is functional, requiring a "circuit that provides a frequency variation signal," which could support a construction covering any structure that performs this function ('851 Patent, col. 11:27-29).
- Evidence for a Narrower Interpretation: The specification’s preferred embodiment describes this element as a specific "low frequency oscillator" (405) that generates a triangular waveform ('851 Patent, col. 6:25-36; Fig. 3). This could support an argument to limit the term to such an implementation.
For the ’876 Patent
- The Term: "digital to analog converter"
- Context and Importance: Infringement of the ’876 patent hinges on the presence of this specific digital architecture. Practitioners may focus on this term because Defendants could argue their circuitry does not meet the technical definition of a D/A converter or that it operates in a fundamentally different way.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim requires a "digital to analog converter coupled to the control input" without specifying its implementation, which may support a construction covering any circuit that receives a digital input from the counter and produces a corresponding analog output ('876 Patent, col. 8:50-52).
- Evidence for a Narrower Interpretation: The detailed description discloses a specific embodiment comprising a set of binary-weighted current sources (e.g., 152, 156, 160, 164) controlled by transistors, which a party could argue limits the scope of the term to that structure ('876 Patent, col. 5:5-18; Fig. 1).
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Defendants induce infringement and contribute to the infringement of third parties by "support[ing] and encourag[ing] others to import, use, offer for sale, and sell... products incorporating Defendants' integrated circuit devices" (Compl. ¶10, ¶13, ¶19, ¶25). This theory appears to be based on supplying the accused components with the knowledge that they will be used in an infringing manner in end-products.
- Willful Infringement: The complaint makes a conclusory allegation that Defendants’ infringement has been and continues to be willful, seeking enhanced damages (Compl. ¶15, ¶21). The pleading does not allege specific facts to support this claim, such as pre-suit notice of the patents or copying.
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of evidentiary proof: given the absence of specific factual allegations in the complaint, can the plaintiff, through discovery, produce technical evidence demonstrating that the accused integrated circuits practice the specific circuit topologies and functionalities required by the asserted claims?
- A key technical question will be one of technological differentiation: do the accused products implement frequency jittering using the analog oscillator-based method of the ’851 patent, the digital counter and D/A converter method of the ’876 patent, or an alternative, non-infringing design? The answer will determine which, if any, patents are infringed.
- A fundamental legal question will be the proper construction of claim terms: the viability of the plaintiff's case will depend heavily on how the court construes key terms like "frequency variation circuit" and "digital to analog converter," and whether the claims, as construed, are determined to be valid over the relevant prior art.