DCT
0:22-cv-02345
NimbeLink Corp v. Digi Intl Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: NimbeLink Corp. (Delaware)
- Defendant: Digi International Inc. (Delaware)
- Plaintiff’s Counsel: Padmanabhan & Dawson, P.L.L.C.
- Case Identification: 0:22-cv-02345, D. Minn., 09/23/2022
- Venue Allegations: Venue is alleged to be proper in the District of Minnesota because Defendant resides in the district, has a regular and established place of business there, and has committed alleged acts of infringement in the district.
- Core Dispute: Plaintiff alleges that Defendant’s XBee® Cellular modem product line infringes two patents related to the design and construction of space-efficient, multi-layer cellular modems for machine-to-machine communications.
- Technical Context: The technology at issue is embedded cellular modems, a key component for connecting "Internet of Things" (IoT) devices to the internet over cellular networks, particularly where other connectivity like Wi-Fi is unavailable.
- Key Procedural History: The complaint alleges a history of business dealings, including acquisition discussions between the parties and the execution of non-disclosure agreements in 2015 and 2016. Plaintiff also alleges it sent cease and desist letters providing notice of the '570 Patent in February 2017 and of both patents-in-suit in July 2022, which forms the basis for its willfulness allegations. The '066 Patent is a continuation of the application that resulted in the '570 Patent.
Case Timeline
| Date | Event |
|---|---|
| 2014-02-06 | Earliest Priority Date for '570 and '066 Patents (Provisional Filing) |
| 2015-06-18 | NimbeLink and Digi enter into a non-disclosure agreement |
| 2016-11-15 | U.S. Patent No. 9,497,570 Issues |
| 2016-11-28 | NimbeLink and Digi enter into a second non-disclosure agreement |
| 2017-01-XX | Digi announces introduction of accused XBee® Cellular modem |
| 2017-02-07 | NimbeLink sends cease and desist letter regarding '570 Patent |
| 2017-12-05 | U.S. Patent No. 9,838,066 Issues |
| 2022-07-19 | NimbeLink sends cease and desist letter regarding '570 and '066 Patents |
| 2022-09-23 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,497,570, "Embedded Wireless Modem" (Issued Nov. 15, 2016)
The Invention Explained
- Problem Addressed: The patent describes a need for improved embedded cellular modems for machine-to-machine (M2M) communications, noting that existing modems were often expensive, required a large physical footprint, and were not always integrated with the latest technology standards (ʼ570 Patent, col. 1:20-33).
- The Patented Solution: The invention is a "space-efficient" cellular modem device built on a multi-layer printed circuit board (PCB). The design achieves its compact size by using a specific layer structure: a first circuit layer on the top side, a second circuit layer on the bottom side, with ground and power plane layers positioned between them (ʼ570 Patent, Abstract; col. 4:19-29). This layered construction, depicted in Figure 6, allows for the efficient placement of components like the cellular transceiver and power management electronics to fit within a standardized, small form factor (ʼ570 Patent, col. 4:31-34).
- Technical Importance: This approach provided a way to add robust cellular connectivity to M2M devices using a pre-certified, compact module, which could reduce hardware costs and development time for IoT product manufacturers (ʼ570 Patent, col. 2:42-50).
Key Claims at a Glance
- The complaint asserts at least independent Claim 1 (Compl. ¶38).
- Essential Elements of Claim 1:
- A space-efficient cellular modem device for machine-to-machine communications.
- A multi-layer printed circuit board (PCB) with a top and bottom side, including: a first circuit layer adjacent the top side, a second circuit layer adjacent the bottom side, a ground plane layer, and a power plane layer, where the ground and power plane layers are "located between the first and second circuit layers."
- A cellular transceiver module with a processor, attached to the top side of the PCB.
- Electrical power-management components attached to the PCB and in electrical communication with the transceiver module.
- A first and second plurality of electrically-conductive pins forming two opposite rows, extending "outwardly and away from the bottom side" of the PCB.
- A communications port electrically connected to the transceiver module for sending and receiving signals.
- The complaint does not explicitly reserve the right to assert dependent claims.
U.S. Patent No. 9,838,066, "Embedded Wireless Modem" (Issued Dec. 5, 2017)
The Invention Explained
- Problem Addressed: As with its parent patent, the '066 Patent addresses the problem of M2M cellular modems being too large and expensive (ʼ066 Patent, col. 1:20-33).
- The Patented Solution: The invention is again a space-efficient modem, but Claim 1 recites a more specific PCB structure than the '570 Patent. It requires "at least four layers," including a first circuit layer, a second ground plane layer, a third power plane layer, and a fourth circuit layer. Crucially, it claims a specific arrangement: the first and fourth layers are soldermasked to form the outer sides of the board, and "the second layer is between the first layer and the fourth layer, the third layer is between the first layer and the fourth layer" (ʼ066 Patent, Claim 1; col. 4:20-30).
- Technical Importance: This specific construction aims to achieve the same goal of a compact, cost-effective, and high-performance embedded modem module for the IoT market (ʼ066 Patent, col. 2:45-53).
Key Claims at a Glance
- The complaint asserts at least independent Claim 1 (Compl. ¶40).
- Essential Elements of Claim 1:
- A space-efficient cellular modem device for machine-to-machine communications.
- A multi-layer PCB with "at least four layers" (first circuit, second ground, third power, fourth circuit), with specific soldermasking and a claimed relative arrangement where the second and third layers are between the first and fourth layers.
- A cellular transceiver module with a processor, attached to the first side of the PCB.
- Electrical power-management components attached to the PCB and in electrical communication with the transceiver module.
- A first plurality of electrically-conductive pins electrically connected to both the transceiver module and the power-management components.
- A second plurality of electrically-conductive pins forming an opposite row.
- A communications port electrically connected to the transceiver module.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
- The accused products are the "Digi XBee® Cellular modem product line," which includes specific models such as the Digi XBee Cellular 3G, Digi XBee Cellular Cat 1 for Verizon, Digi XBee Cellular Cat 1 for AT&T, Digi XBee 3 Cellular LTE-M/NB-IoT, and Digi XBee 3 Cellular LTE Cat 1 (Compl. ¶36).
Functionality and Market Context
- The accused products are embedded cellular modems designed to provide M2M and IoT devices with cellular network connectivity (Compl. ¶¶ 8, 36). The complaint alleges that these products are marketed as being very small, quoting a Digi website that calls the modem the "‘smallest end-device certified cellular modem’" (Compl. ¶39, Chart). The complaint also alleges that the accused product line is "nearly identical" to Plaintiff's own Skywire™ product (Compl. ¶36). A photograph provided in the complaint shows the bottom side of an accused modem, highlighting the placement of various components including power management circuitry (Compl. p. 12, "Power Management components").
IV. Analysis of Infringement Allegations
'570 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a multi-layer printed circuit board defining a top side and a bottom side and including a first circuit layer adjacent the top side, a second circuit layer adjacent the bottom side, a ground plane layer, and a power plane layer, the ground and power plane layers located between the first and second circuit layers; | The Digi XBee Cellular Modem is alleged to be a multi-layer PCB with top and bottom sides. The complaint provides a side-view photograph identifying six layers, alleging that "Layer1" is the first circuit layer, with the ground and power plane layers (Layers 2 and 3) located between it and other circuit layers. | ¶39, Chart | col. 4:19-29 |
| a cellular transceiver module configured to communicate over a cellular wireless cellular network, the cellular transceiver module comprising a processor and attached to a top side of the multi-layer printed circuit board; | The accused modem is alleged to have a cellular transceiver module (a Telit LE866-SV1) attached to its top side. The complaint includes a top-view photograph identifying this module. | ¶39, Chart | col. 4:44-50 |
| electrical power-management components attached to the multilayer printed circuit board, the power-management components in electrical communication with the cellular transceiver module; | The accused modem is alleged to have power management components on its PCB that are in electrical communication with the transceiver. A bottom-view photograph identifies these components. | ¶39, Chart | col. 4:1-4 |
| a first plurality of electrically conductive pins... and a second plurality of electrically conductive pins... extending outwardly and away from the bottom side of the multi-layer printed circuit board... | The accused modem is alleged to have two rows of pins extending from the bottom side of the PCB. A photograph showing the pin rows is provided as evidence. | ¶39, Chart | col. 4:6-14 |
| a communications port in electrical communication with the cellular transceiver module... | The accused modem is alleged to have a communications port (antenna port) in electrical communication with the transceiver. A photograph of the board's underside identifies this port. | ¶39, Chart | col. 4:59-65 |
- Identified Points of Contention:
- Scope Questions: A central question may be whether the term "space-efficient" is definite and, if so, whether the accused device meets that limitation. The complaint attempts to satisfy this by citing Defendant's own marketing materials describing its product as the "smallest" certified modem (Compl. ¶39, Chart).
- Technical Questions: The claim requires ground and power plane layers to be "located between the first and second circuit layers." The complaint's evidence shows a six-layer board (Compl. p. 9, "Layer1"..."Layer6"). The plaintiff's infringement theory appears to map the claimed "first circuit layer" to the accused device's "Layer 1" and the "second circuit layer" to an outer layer like "Layer 6". A dispute may arise over whether this mapping is technically and legally sound, or if the claim implies a more direct, four-layer structure as depicted in the patent's Figure 6.
'066 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a multi-layer printed circuit board... including at least four layers... wherein... the second layer is between the first layer and the fourth layer, the third layer is between the first layer and the fourth layer... | The complaint alleges the accused modem has at least four layers and provides a side-view image identifying six distinct layers. It alleges that "Layer 2" and "Layer 3" are located between "Layer 1" and "Layer 6," which it implicitly identifies as the claimed "fourth layer". | ¶41, Chart | col. 4:20-30 |
| a cellular transceiver module... attached to the first side of the multi-layer printed circuit board; | The complaint alleges a cellular transceiver module is attached to the first side of the accused modem's PCB, providing a top-view photograph with the module circled. | ¶41, Chart | col. 4:50-57 |
| a first plurality of electrically-conductive pins... one or more... pins in electrical connection with the cellular transceiver module and one or more... pins in electrical connection with the electrical power-management components; | The complaint alleges the accused modem's pins are electrically connected to both the transceiver and power management components, providing a photo of the pin rows as evidence of the structure. | ¶41, Chart | col. 6:28-40 |
| a communications port in electrical communication with the cellular transceiver module... | The complaint alleges the accused modem has a communications port for the transceiver, providing a photograph of the accused device's underside with the port circled. | ¶41, Chart | col. 6:49-54 |
- Identified Points of Contention:
- Technical Questions: The infringement theory for the '066 Patent hinges on interpreting the claimed four-layer structure onto the accused six-layer PCB. The claim requires the second and third layers to be between the "first layer and the fourth layer." The complaint's allegation that this is met because Layers 2 and 3 of the accused device are between its physical Layers 1 and 6 raises the question of whether "the fourth layer" of the claim can be read to mean the sixth physical layer of the accused product. A defendant may argue this is a structural mismatch.
- Evidentiary Questions: The claim requires at least one pin in the first row to be electrically connected to the transceiver and at least one pin to be connected to the power-management components. While the complaint asserts this is met and provides a photograph of the pins (Compl. p. 19), it does not provide detailed evidence, such as a circuit diagram or trace analysis, to substantiate this specific dual-connectivity requirement.
V. Key Claim Terms for Construction
The Term: "located between the first and second circuit layers" ('570 Patent, Claim 1)
- Context and Importance: This phrase defines the fundamental structure of the PCB stack-up. The infringement analysis depends on how the accused six-layer board maps onto this claimed structure. Practitioners may focus on this term because its interpretation will determine if a board with more than four layers, and potentially with other layers interspersed, can meet the limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim language does not explicitly forbid other layers from also being between the first and second circuit layers. A party could argue "between" simply establishes a relative ordering, not that the ground and power planes must be the only layers between the two circuit layers.
- Evidence for a Narrower Interpretation: The patent's Figure 6 depicts a specific four-layer stack-up where Layers 2 (GND) and 3 (POWER) are positioned contiguously between Layer 1 (Circuit Top) and Layer 4 (Circuit Bottom). This embodiment could be used to argue that "between" implies a more constrained, direct relationship representative of a four-layer design.
The Term: "the fourth layer" (in the context of a board with "at least four layers" where "the second layer is between the first layer and the fourth layer") ('066 Patent, Claim 1)
- Context and Importance: This term is critical because the plaintiff's infringement theory requires "the fourth layer" of the claim to correspond to the sixth physical layer of the accused product. The viability of the infringement case against the '066 Patent turns almost entirely on this construction.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim preamble recites "at least four layers," which explicitly contemplates that the board could have more than four. In such a case, a party could argue that "the fourth layer" is a functional term for the outermost circuit layer on the second side of the board, whatever its physical number might be (e.g., Layer 4 in a 4-layer board, Layer 6 in a 6-layer board).
- Evidence for a Narrower Interpretation: The claim body repeatedly and specifically refers to "the first layer," "the second layer," "the third layer," and "the fourth layer." A party could argue this numbered recitation, coupled with the detailed description and Figure 6, defines a specific four-layer architecture, and the term "the fourth layer" cannot be arbitrarily mapped to a different physical layer (e.g., Layer 6) in a different architecture not explicitly described.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Digi induced infringement of both patents. The factual basis for this claim is the allegation that Digi had knowledge of the patents from pre-suit cease and desist letters and "knowingly encouraged and induced its customers to infringe" by selling the Accused Products for their intended infringing use (Compl. ¶¶ 50, 61).
- Willful Infringement: The complaint alleges willful infringement based on pre-suit knowledge. It specifically alleges that Digi had "actual knowledge" of the '570 Patent as early as February 7, 2017, and of the '066 Patent as early as July 19, 2022, from cease and desist letters. The complaint asserts that despite this knowledge, Digi continued its allegedly infringing activities (Compl. ¶¶ 42-44, 53, 64).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of structural mapping: Can the specific layer configurations of the accused six-layer PCB be shown to meet the structural limitations of the asserted claims, which describe four-layer architectures? The outcome will likely depend on whether the court construes the claims as describing a general relative arrangement or a specific, rigid architecture.
- A key question of claim construction will be one of definitional scope: In the context of the '066 patent reciting "at least four layers," can the term "the fourth layer" be construed to mean the outermost circuit layer of a board with more than four layers (e.g., the sixth layer), as the plaintiff's infringement theory requires?
- A central factual question will concern willfulness: Given the alleged history of business negotiations and multiple pre-suit notice letters, a court will need to determine whether the defendant's continued sale of the accused products, if found to be infringing, rose to the level of deliberate or reckless conduct sufficient to justify enhanced damages.