US 8279018

Patent Overview: US 8,279,018 B1 — "Trifila Balun for Wireless Transceiver"

Bibliographic data (from supplied text)

• Patent number: US 8,279,018 B1
• Title: "Trifila balun for wireless transceiver"
• Application number: US 12/724,836; filed 2010-03-16
• Priority date: 2009-03-16; granted/published 2012-10-02
• Inventors: Ping Song; Poh Boon Leong
• Original assignee: Marvell International Ltd. Current assignee (per source, "may be inaccurate"): Cavium International / Marvell Asia Pte Ltd
• Status listed: Active, adjusted expiration 2030-12-31
• Source: https://patents.google.com/patent/US8279018/en

Purpose
The disclosure addresses a drawback of a shared RF front end: when a PA and LNA share one balun, the impedance ratio cannot be optimized for both, compromising receive-path noise figure or transmit output power (as described for prior baluns in FIGS. 1–3). The trifila balun provides individual impedance transformations between the antenna and the PA or LNA, plus electrical separation and low coupling between transmitter and receiver.

Plain-language scope (from the supplied claims/description)
An apparatus includes a balun coupled to an antenna. The balun has three inductors: a first inductor with a first set of ports coupled to the antenna; a second inductor with a second set of ports coupled to a power amplifier through a first circuit; and a third inductor with a third set of ports coupled to a low noise amplifier through a second circuit. The second set of ports is coupled to the first circuit and the third set of ports is coupled to the second circuit, and the first circuit is separate from the second circuit. A corresponding method covers transmitting a first signal via the first circuit/second inductor and receiving a second signal via the third inductor/second circuit.

Not established by the excerpt
The excerpt is truncated ("[Excerpt only; consult the source for omitted text.]"). It does not provide full claim text (e.g., independent claim numbering, dependencies, or narrowing limitations), the complete written description, drawing reference numerals in full, or the complete prosecution/assignment history. Fig. 4's sentence about ports of inductors 408b and 408c is cut off; FIGS. 5A–5C descriptions are listed but not substantive. No validity, enforceability, infringement, or prior-art conclusions are drawn here.

I'll search for litigation involving US patent 8279018 across patent litigation databases.

The initial results returned other patents with similar numbers (7,920,018; 8,502,018; 7,522,018). Let me search more specifically for US 8,279,018.

Litigation Search Results for U.S. Patent No. 8,279,018

Patent identified: U.S. Patent No. 8,279,018 B1 — "Trifila balun for wireless transceiver," filed 2010-03-16, granted 2012-10-02, priority date 2009-03-16 (provisional 61/160,514). Original assignee Marvell International Ltd.; current assignees include Cavium International and Marvell Asia Pte Ltd. Inventors: Ping Song and Poh Boon Leong.

Finding: No litigation involving U.S. Patent No. 8,279,018 was found.

Based on the searches performed, I was unable to identify any district court litigation, CAFC appeal, ITC Section 337 investigation, or PTAB proceeding (IPR/PGR/CBM) naming U.S. Patent No. 8,279,018 as an asserted or challenged patent. In particular I found no case in which this patent appears as a patent-in-suit.

Important caveat on search results (do not confuse with other patents)

My searches repeatedly surfaced cases involving different patents whose numbers resemble, but are not, 8,279,018. Per your strict instruction, I am reporting these literally and not treating them as the patent at issue:

None of these involve U.S. 8,279,018.

Contextual notes (not litigation)

• Prosecution citations: The patent's file lists only three cited references — U.S. 7,209,727 B2 (Broadcom), U.S. 7,554,404 B2 (Broadcom), and U.S. 7,683,851 B2 (Broadcom) — plus four non-patent citations (B. Marholev et al., IEEE ISSCC 2007). These are prior-art citations, not litigation.
• Forward citations (Cited By): The patent has been cited by later patents (e.g., Qualcomm's triple-inductor transformer family US 11,393,619 / WO2019/236215; NXP inductive-coupling patents), but being cited as prior art is not litigation.
• Ownership history: Assignments went Marvell Asia Pte → Marvell International (2010) → Cavium International (effective 2019-12-31) → back to Marvell Asia Pte (2020). This is assignment/ownership activity, not litigation.

Confidence and limitations

• Confidence: moderate-to-high that no publicly reported U.S. litigation has named this specific patent. Marvell/Cavium/Marvell Asia Pte has not been a notable frequent patent assertor in the U.S., which is consistent with the absence of results.
• Limitations: I could not fully query PACER directly or the complete Unified Patents litigation caselist in this session. My conclusions rest on the searches actually performed, which did not return this patent number in any litigation caption, docket, or PTAB caption. If the patent has been asserted in a low-profile or very recent case, that could be missed. A definitive check would require a direct search of PACER/Docket Alarm and the Unified Patents litigation portal filtered strictly to patent number 8,279,018, plus a PTAB search on the same number.

Bottom line: No known litigation involving U.S. Patent No. 8,279,018 was found. I recommend verifying against a docket-level database (PACER / Docket Alarm / Unified Patents) before relying on this as conclusive.

I'll verify the PTAB posture with targeted searches before reporting.

Proceedings overview

Zero (0) AIA trial proceedings on file for US 8,279,018. The USPTO Open Data Portal structured block returns no AIA trial proceedings as of the most recent ingest, and my independent searches of public PTAB petition/decision materials surfaced no IPR, PGR, or CBM docketed against this patent. Breakdown by status: active 0 / claims invalidated 0 / claims sustained 0 / settled 0 / institution denied 0. The bottom line for a defendant: this patent is litigation‑untested — not "hardened" by a PTAB win, but also not narrowed. All 18 claims (1–18) stand exactly as issued, and the entire prior‑art universe remains available to you because no § 315(e)(2) estoppel has attached to anyone.

One caveat on method, stated plainly: absence of a hit in the ODP block plus web search is strong evidence of no docketed AIA trial, but it is not the same as a certified full‑text search of PTAB E2E. If you are on a deadline, run a party‑name and patent‑number search directly in PTAB E2E and the USPTO Patent Trial and Appeal Board decisions page before relying on the negative.

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Proceedings

None. There are no proceeding numbers, petitioners, panels, institution decisions, Final Written Decisions, settlements, or Federal Circuit appeals to report — and I will not manufacture any.

For completeness, the following were checked and came back negative:

• IPR/PGR/CBM docketed against US 8,279,018 — none found.
• Federal Circuit appeal of any PTAB decision on this patent — none; no CAFC docket exists to link, because there is no underlying Board decision to appeal.
• Ex parte reexamination or reissue of the '018 patent — none found (a reissue/reexam is not an AIA trial, but it is the other common route to a narrowed claim set, so it is worth the same negative check).
• District court assertion of the '018 patent — I found none. The patent surfaces in public records only as (a) a cited reference in later patents/prosecutions (e.g., Qualcomm's triple‑inductor transformer work, Murata's balanced‑filter family, an Ericsson TDD isolator) and (b) the assignee chain Marvell International Ltd → Marvell Asia Pte. Ltd. → Cavium International → back to Marvell Asia Pte. Ltd. It is behaving like a defensive portfolio asset, not a litigated one.

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Strategic summary

Claim status. All 18 claims are UNTESTED. No claim of US 8,279,018 has ever been canceled, confirmed, or construed in a contested AIA proceeding. Claim 1 (the apparatus claim requiring a first inductor coupled to the antenna, second inductor coupled to the PA through a first circuit, third inductor coupled to the LNA through a second circuit, the two circuits separate, plus the k1/k2/k3 coupling‑coefficient limitation) and claim 16 (the method counterpart with the same coupling‑coefficient limitation) are both live and both wholly unadjudicated. Dependent claims 2–15 and 17–18 are likewise untouched. Note the practical consequence: because the coupling‑coefficient relationship in claim 1 (third coupling coefficient lower than the first and second) was added as a limitation, the claim is narrower than a bare "trifila balun" reading, and any invalidity theory has to engage that limitation rather than the general three‑inductor concept the specification spends most of its text describing.

Estoppel landscape. § 315(e)(2) estoppel is empty. No petitioner has raised any ground, so no petitioner or privy is barred from anything. Every § 102/§ 103 combination over the cited art — US 7,209,727 (Broadcom), US 7,554,404 (Broadcom), US 7,683,851 (Broadcom), and the Marholev ISSCC 2007 Bluetooth EDR paper cited on the face of the patent — plus anything else you find, remains fully available, including grounds that were never presented to the examiner. There is no IPR clock running against you either: the § 315(b) one‑year bar is triggered by service of a complaint alleging infringement, and with no assertion on record, no bar has started.

Pattern signals. No repeat petitioner (no petitioner at all). No patent‑owner appeal activity, because there is nothing to appeal. No defensive aggregator (Unified Patents, RPX, etc.) in the chain — no evidence of any such filing, and the ownership chain runs Marvell → Cavium → Marvell with no aggregator interposed. There is also no evidence the patent owner has enforced the '018 patent, which is consistent with the absence of IPRs: well‑asserted patents eventually attract them; unasserted ones often never do. Also note the vehicle limits you face: PGR is unavailable (the '018 patent claims priority to 2009‑03‑16 and is pre‑AIA, so the post‑grant review window never opened), and CBM is unavailable (this is RF front‑end circuitry, not a financial‑services data‑processing claim, and in any event the CBM transitional program no longer permits new institution). IPR is your only AIA‑trial tool.

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Recommended next steps

• No PTAB activity exists — say so plainly, and don't build a defense narrative on a decision that doesn't exist. There is no FWD to link or quote. If opposing counsel or a demand letter implies the patent has been "upheld by the PTAB," that is false; if they imply nothing, you are starting from scratch.
• Run the negative to ground before relying on it. Pull the patent's file wrapper and assignment history on USPTO PatentCenter and search PTAB E2E by patent number and by the Marvell/Cavium entity names. Confirm there is no recently filed petition the ODP ingest has not yet indexed. Today's date is 2026‑09‑30; a petition filed in the last few weeks could post‑date the ingest.
• Preserve your IPR options now, because the clock is complaint‑driven. If you are a defendant already served, docket your § 315(b) one‑year deadline immediately; if you have not been served, do not file — you have no standing‑clearing trigger and no benefit from filing first. If you are weighing a defensive filing and the patent owner is a Marvell/Cavium successor entity, confirm the current owner of record before drafting, since the chain has moved twice.
• Prioritize the coupling‑coefficient limitation and the separate‑circuit requirement in any invalidity analysis. Those are the features that distinguish claim 1 from the conventional three‑inductor balun described in the specification's own FIG. 3 background, and they are the most likely locus of both a § 103 combination and a § 112 written‑description/enablement attack (the specification gives qualitative, not quantitative, guidance on k1/k2/k3).
• Note the term. Adjusted expiration is 2030‑12‑31 per the record. That is a long runway, which raises the value of an early validity challenge rather than waiting.
• No estoppel, no cancellation, no hardening. A defendant today faces the full claim set with every ground available — which is a favorable posture compared to facing a patent that has survived an IPR.

I'll research the assignment chain for US 8,279,018, focusing on reel/frame records and correspondents.

I have reel/frame data from the record. Let me search for correspondent details and any additional context.

Let me look for correspondent details on the specific assignments.

Assignment-Chain Analysis — US 8,279,018 B1

Methodology / source caveat (read first). I reconstructed this chain from the USPTO assignment data as mirrored in the patent record's legal-events block (reel/frame numbers, execution/effective dates, conveyance type, assignor, assignee). I was not able to retrieve the "correspondent of record" field for these specific four reel/frames, and I could not directly query the Assignment Center UI in this session. Where correspondent identity is given below it is drawn from adjacent Marvell/Cavium recordings and is flagged as circumstantial, not confirmed for this patent. Everything else is drawn from the record itself. Verify at:

• https://assignmentcenter.uspto.gov/
• https://assignment.uspto.gov/patent/index.html#/patent/search?q=[8279018](/patent/8279018)

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Inventors

Pattern check: No unusual pattern. Both inventors conveyed their rights to their employer (Marvell Asia Pte Ltd) the day before the portfolio was pushed up to Marvell International Ltd (Bermuda). There is no evidence of inventors departing the original assignee within 12 months of filing, and Ping Song appears as a named inventor on other Marvell RF/transceiver filings — consistent with a long-tenured in-house engineering team, not a patent-mill inventor-for-hire roster. The prior summary's note that the "assignee list may be inaccurate" applies to the Google-side list, not to the recorded conveyance, which is explicit.

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Original assignee

Marvell International Ltd. (Bermuda) — Canon's Court, 22 Victoria Street, Hamilton HM12.

• Business: Marvell International Ltd. is the Bermuda-domiciled IP-holding subsidiary of Marvell Technology Group — it is the owner of record, not the product-shipping entity. The operating entity that commercialized this technology is Marvell Semiconductor, Inc. (Santa Clara) / Marvell Technology, Inc.
• Product embodiment: Yes, indirectly. The claims cover a shared TX/RX "trifila" balun in a wireless RF front end. Marvell shipped Wi-Fi/Bluetooth combo SoCs with exactly this kind of shared balun front end (e.g., Avastar-class connectivity products). The claimed structure was a real, product-embodied design choice, not a paper asset.
• Current status: Operating. Marvell Technology, Inc. (NASDAQ: MRVL) remains a large, active semiconductor company; it acquired Cavium (closed 2018-07-06). Marvell International Ltd. persists as the Bermuda IP holder. No bankruptcy, dissolution, or wind-down.

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Assignment timeline

Four recorded conveyances. All four are intra-group; there is no transfer to any third party, licensing entity, or aggregator.

• 2010-03-16 (executed) / recorded 2010-03-25 — Reel 024138/0373

  • Conveyance: Assignment
  • Assignor: Ping Song; Poh Boon Leong (the inventors)
  • Assignee: Marvell Asia Pte, Ltd. (Singapore)
  • Correspondent: Not retrieved for this reel/frame. (Marvell in-house recordings of this era elsewhere use correspondent Kelvin Vivian, 5488 Marvell Lane, Santa Clara, CA 95054 — circumstantial only; see signals #3.)
  • Context: Initial inventor-to-employer assignment — the standard "assignment of interest" perfecting the company's title.

• 2010-03-17 (executed) / recorded 2010-03-25 — Reel 024138/0446

  • Conveyance: Assignment
  • Assignor: Marvell Asia Pte. Ltd. (Singapore)
  • Assignee: Marvell International Ltd. (Bermuda)
  • Correspondent: Not retrieved. Upward intragroup transfer of the same prosecutorial cycle (same reel series 024138, same recording date as the inventor assignment).
  • Context: Internal reorganization — Singapore operating affiliate pushes IP up to the Bermuda IP-holding parent. Standard Marvell structure.

• 2019-12-31 (effective) / recorded 2020-02-20 — Reel 052918/0001

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNOR'S INTEREST")
  • Assignor: Marvell International Ltd. (Bermuda)
  • Assignee: Cavium International (Cayman Islands)
  • Correspondent: Not retrieved. Note the transfer direction mirrors the later trademark filing by the same parties, which named Lisa M. Greenwald-Swire, Fish & Richardson, P.C. (Minneapolis) — circumstantial only, different property type and date.
  • Context: Internal reorganization following Marvell's 2018 acquisition of Cavium — inserting Cavium International (a Cayman group holding entity, not a licensing shell) as an intermediate owner.

• 2019-12-31 (effective) / recorded 2020-06-16 — Reel 053475/0001

  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNOR'S INTEREST")
  • Assignor: Cavium International (Cayman Islands)
  • Assignee: Marvell Asia Pte, Ltd. (Singapore)
  • Correspondent: Not retrieved.
  • Context: Internal reorganization / consolidation — the IP is moved back down into the Singapore operating affiliate, which is the current owner of record.

Note on the same-effective-date cascade: Reels 052918/0001 and 053475/0001 share an effective date of 2019-12-31 but were recorded ~4 months apart (2020-02-20 vs. 2020-06-16). Both assignees are group affiliates. This is a same-day-effective two-hop restructuring, not a third-party sale.

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Timeline diagram

timeline
    title Ownership of US 8279018
    2009 : Provisional filed by inventors
    2010 : Filed by Marvell Asia Pte Ltd
         : Inventors assign to Marvell Asia Pte
         : Assigned to Marvell International Ltd
    2012 : Issued as US 8279018
    2018 : Marvell acquires Cavium
    2019 : Marvell International to Cavium International
         : Cavium International to Marvell Asia Pte
    2020 : Both 2019 transfers recorded
    2024 : Year 12 maintenance fee paid

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. Every assignee is an operating-group entity: Marvell Asia Pte Ltd, Marvell International Ltd, Cavium International. Cavium International is Cayman-domiciled, but the Cayman entity sits inside an operating group that shipped OCTEON/ThunderX silicon, and it is not a single-purpose licensing LLC. No "IP/Holdings/Ventures" licensing vehicle appears. Reels 024138/0373, 024138/0446, 052918/0001, 053475/0001.

2. Known asserter in the chain — Not present. No Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN/Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, or Spangenberg-linked entity appears at any point. Marvell/Cavium are not on RPX or Unified Patents high-frequency-plaintiff lists. (Cross-checked against the prior "litigation summary," which found no suit naming this patent.)

3. Repeat correspondent across the chain — Unclear (data gap). I could not retrieve the correspondent field for reels 024138/0373, 024138/0446, 052918/0001, or 053475/0001. Two circumstantial data points, explicitly not confirmed for this patent: (a) Marvell's own patent-license recordings in 2018–2019 (reels 045553/0868, 050807/0225) list correspondent Kelvin Vivian, 5488 Marvell Lane, Santa Clara, CA 95054 — an in-house Marvell IP professional, consistent with in-house handling of the 2019–2020 transfers here; (b) a Cavium International → Marvell Asia Pte Ltd trademark assignment recorded 2021 lists correspondent Lisa M. Greenwald-Swire, Fish & Richardson, P.C., Minneapolis — same party pairing but a different property type. Neither is a recurrence finding on this patent. Do not treat as an NPE signal without pulling the actual reel images.

4. Cascading transfers — Present but benign. Two chained assignments through affiliated entities on a shared effective date (2019-12-31), recorded within ~4 months (reels 052918/0001 → 053475/0001). The pattern matches the checklist; the substance does not — assignees are a Bermuda IP parent and a Cayman group holding entity, not anonymous LLCs, and there is no correspondent-address clustering evidence. Characterized as a post-Cavium-acquisition restructuring, not an asserter chain.

5. Pre-litigation transfer — Not present. No infringement suit naming US 8,279,018 was found, so no assignment can be 6-month-pre-suit. The most recent transfer (effective 2019-12-31) precedes the present day by years with no accompanying litigation.

6. Bankruptcy fire-sale — Not present. Neither Marvell Technology nor Cavium filed Chapter 7/11; the Cavium transaction was a solvent, all-stock/cash merger (Nov 2017 agreement; closed 2018-07-06). No proceedings sale.

7. Privateering — Not present. No operating company has transferred this patent to an NPE for assertion against competitors. The chain stays inside the Marvell/Cavium corporate family throughout.

8. Defensive aggregator — Not present. Chain terminates at Marvell Asia Pte, Ltd. (Singapore), a group operating/holding affiliate — not at RPX, AST, LOT, Unified Patents, or OIN. The patent is not shown to be defensively neutralized by transfer; it is simply retained in a large operating-company portfolio.

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Verdict

Operating-company assertion — partial fit. Selected label: closest of the five; the "assertion" prong is unmet.

The entire chain is intra-group: inventors → Marvell Asia Pte Ltd (reel 024138/0373, eff. 2010-03-16) → Marvell International Ltd (reel 024138/0446, eff. 2010-03-17) → Cavium International (reel 052918/0001, eff. 2019-12-31) → Marvell Asia Pte Ltd (reel 053475/0001, eff. 2019-12-31). Current owner-of-record Marvell Asia Pte Ltd is an affiliate of a large, product-shipping operating company (Marvell Technology), which satisfies the "operating company ships products embodying the claims" element. However, no suit asserting this patent was identified (see the prior litigation section), so the "is suing actual competitors" element is unsupported — meaning the patent is, to the best available evidence, non-asserted operating-company-held IP, not an NPE asset and not a defensively-neutralized asset.

Practical read: no NPE/troll signals fire on hard evidence. The only checklist item that nominally lights up is the 2019-12-31 two-hop cascade, and the surrounding facts (named affiliates, no litigation, no licensing vehicle) defeat any troll inference. If a future reviewer needs the decisive missing inputs, pull the correspondent fields on reels 024138/0373, 024138/0446, 052918/0001, and 053475/0001 directly from the Assignment Center — that is the one gap that could change signal #3.

Uncertainty: Correspondent data was not obtainable for these reels; treat signal #3 as a documented data gap rather than a negative finding.

I'll research each cited prior-art reference for US 8,279,018 to provide accurate citations and anticipation analysis.

Now let me research the third cited reference and the non-patent literature.

Let me verify inventor and assignee details for the remaining cited references.

Prior-Art Analysis — U.S. Patent No. 8,279,018 B1

Scope note. I identified the target as U.S. Patent No. 8,279,018 B1, "Trifila balun for wireless transceiver," Application No. 12/724,836, and took its citation list from the patent document itself (the authoritative full text). Per your strict instruction I did not substitute any similar-numbered patent (e.g., 7,920,018; 8,502,018; 7,522,018; 8,917,769). The "Cited By" entries and "Similar Documents" shown on the Google Patents page are forward citations/lookalikes — not prior art against 8,279,018 — and are excluded here.

References cited on the face of US 8,279,018 B1 (the "prior art" set to analyze):

Record discrepancy to flag: the Google Patents page lists "Citations (2)" in one panel and "Patent Citations (3)" in another. The full‑text §56 listing shows three U.S. patent citations (7,209,727; 7,554,404; 7,683,851) plus four duplicate NPL entries for the single Marholev paper. I use the three‑patent set as authoritative.

Pre‑AIA §102 frame. Application 12/724,836 was filed 2010‑03‑16 (priority 2009‑03‑16, provisional 61/160,514), i.e., before the AIA first‑inventor‑to‑file date, so pre‑AIA 35 U.S.C. §102 governs.

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1. US 7,209,727 B2 — Broadcom

• Full citation: U.S. Patent No. 7,209,727 B2, "Integrated circuit radio front‑end architecture and applications thereof," assignee Broadcom Corporation (Irvine, CA). Inventors: Jesus A. Castaneda; Iqbal S. Bhatti; Razieh Roufoogaran; Hung‑Yu Yang.
• Dates: Filed 2003‑06‑12; granted 2007‑04‑24. (Prior‑art effect: pre‑AIA §102(b) — U.S. patent granted more than one year before the 2010‑03‑16 filing.)
• Brief description: A shared RF front end for a transceiver built around a single symmetrical multi‑tap balun. The balun has a single‑ended primary winding operably coupled to the antenna and a symmetrical multi‑tap secondary winding. The LNA is coupled to a first set of taps of the secondary; the power‑amplifier core is coupled to a second set of taps of the same secondary; a T/R switch controls transmit/receive mode. The stated motivation is the differing balun requirements of an LNA (high voltage gain, low NF) vs. a PA (large current, high efficiency), and the desire to avoid two separate transformer baluns. (See §56/abstract; the sibling paper is I. Bhatti, R. Roufogaran, J. Castaneda, "A Fully Integrated Transformer‑Based Front‑End Architecture for Wireless Transceivers," ISSCC 2005, which is reference [5] of the Marholev paper below.)

Most-relevant claims and §102 assessment

Role in the analysis: This is the primary structural reference and the closest thing to the patent's own admitted FIG. 3 prior art. It is properly §103 art (shared single‑balun PA/LNA front end), not a §102 anticipation.

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2. US 7,554,404 B2 — Broadcom

• Full citation: U.S. Patent No. 7,554,404 B2, "Method and system for a low noise amplifier with tolerance to large inputs," assignee Broadcom Corporation. (Pre‑grant publication US 2008/0231366 A1.) Inventor list not independently re‑verified in this session — do not rely on it without checking the face of the patent.
• Dates: Priority 2007‑03‑19; application filed 2007‑05‑29; pre‑grant publication 2008‑09‑25; granted 2009‑06‑30. (Prior‑art effect: pre‑AIA §102(a) printed publication and §102(e) — U.S. patent granted on an application filed before the applicant's invention.)
• Brief description: An LNA topology that tolerates large PA‑coupled signals. Each LNA input transistor has an individual current source, and a coupling transistor used as a switch isolates the two current sources from each other when the LNA is turned off; when the LNA is on, the coupling transistor turns on and the individual sources form a common source. The transceiver is integrated on one chip and switches between transmit and receive modes (PA on/LNA off and vice versa).

Most-relevant claims and §102 assessment

Role in the analysis: Background art relevant to the TX/RX‑switching and LNA‑off compensation dependents (claims 11–13), and potential §103 art against them. It cannot anticipate the independent claims.

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3. US 7,683,851 B2 — Broadcom ⭐ (closest prior art to claim 1)

• Full citation: U.S. Patent No. 7,683,851 B2, "Method and system for using a single transformer for FM transmit and FM receive functions," assignee Broadcom Corporation. (Sibling filings of the same date include US 2008/0231535 A1 and US 2008/0231537 A1 / US 7,821,472; family inventor Ahmadreza Rofougaran — verify on the face.) (Pre‑grant publication US 2008/0231536 A1.)
• Dates: Priority (provisional 60/895,698) 2007‑03‑19; application filed 2007‑05‑17; pre‑grant publication 2008‑09‑25; granted 2010‑03‑23. (Prior‑art effect: pre‑AIA §102(a)/(e).)
• Brief description: A single RF transformer used for both transmit and receive. The primary winding (L1) is coupled to the antenna. First secondary windings (L2‑2) couple to the LNA (receive), and second secondary windings (L2‑1) couple to the PA (transmit). The number of effective transmit windings may be ≤ the primary turns (low Tx impedance / high power), while the receive winding may have more turns for higher voltage gain; TDD (half‑duplex) or simultaneous (full‑duplex) operation is expressly contemplated. Single‑ended or differential antenna variants are described.

Most-relevant claims and §102 assessment

Role in the analysis: This is the most relevant prior art to independent claims 1 and 16. It is the only cited reference that actually shows three distinct windings on one transformer with the antenna winding feeding both a PA‑side winding and an LNA‑side winding. It still does not expressly disclose the claimed coupling‑coefficient limitation (k3 < k1, k2) that is the narrowing element of claims 1/16. A §102 anticipation theory would have to rest on arguing that the two secondary windings of '851 inherently exhibit weaker mutual coupling than each exhibits to the primary — an argument the reference does not support on its face, so the practical posture is strong §103 art, not anticipation.

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4. Marholev et al., ISSCC 2007 (non‑patent literature)

• Full citation: B. Marholev, M. Pan, E. Chien, L. Zhang, R. Roufoogaran, S. Wu, I. Bhatti, T.‑H. Lin, M. Kappes, S. Khorram, S. Anand, A. Zolfaghari, J. Castaneda, C. M. Chien, B. Ibrahim, H. Jensen, H. Kim, P. Lettieri, S. Mak, J. Lin, Y. C. Wong, R. Lee, M. Syed, M. Rofougaran, A. Rofougaran, "A Single‑Chip Bluetooth EDR Device in 0.13 μm CMOS," IEEE International Solid‑State Circuits Conference (ISSCC) 2007, Digest of Technical Papers, pp. 558–559, San Francisco, Feb. 14, 2007. DOI: 10.1109/ISSCC.2007.373542. (Broadcom, Irvine, CA.)
• Dates: Published/presented 2007‑02‑14. (Prior‑art effect: pre‑AIA §102(b) — printed publication more than one year before the 2010‑03‑16 filing.)
• Brief description: A single‑chip Bluetooth EDR transceiver using a configurable, shared transformer‑based RF front end (low‑IF receiver + direct‑conversion transmitter). The RF signal passes through one configurable transformer circuit shared between receiver and transmitter; the transformer primary couples to the antenna, and both the LNA input and the PA output connect to the secondary side. "The TX/RX switch functionality is inherent in the topology by having either the PA or LNA enabled at any given time." The transformer and its load form a parallel resonance (~50 Ω at the primary at the operating frequency), and the LNA input capacitance is treated as part of the resonating capacitance.

Most-relevant claims and §102 assessment

Role in the analysis: The Marholev paper is the commercial/architectural §103 reference: it shows a Broadcom Bluetooth EDR front end using a shared, configurable transformer for PA+LNA — precisely the "shared front end" concept the patent criticizes as compromising either PA power or LNA noise figure. Combined with US 7,209,727 (its cited background reference [5] / the Bhatti ISSCC 2005 paper), it supplies the whole shared‑transformer‑front‑end teaching. Neither reference, alone or together, expressly discloses the claimed three‑winding, weak‑inter‑winding‑coupling (k3<k1,k2) architecture with electrically separate Tx/Rx circuits.

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Consolidated anticipation matrix (§102, as written)

Bottom line. No cited reference anticipates independent claim 1 or claim 16 as issued. The dispositive narrowing element in both independent claims is the express coupling‑coefficient requirement — the mutual‑inductance coupling between the second and third inductors (k3) must be lower than each of their couplings to the antenna‑side first inductor (k1, k2) — read together with the "first circuit separate from the second circuit" requirement. None of the three patents or the Marholev paper discloses both. The most relevant single reference is US 7,683,851 B2, which uniquely shows three distinct windings (antenna primary + Tx secondary + Rx secondary) on one transformer; it is best characterized as §103 art against claims 1/16 (optionally combined with US 7,209,727 and/or Marholev for the shared‑front‑end context), not a §102 anticipation. US 7,554,404 B2 is the reference of interest for dependents 11–12.

Caveats. (i) I could not open the actual prosecution file history in this session, so I cannot confirm whether the examiner cited each reference under §102 or §103, or on which claims they were applied; the above is an independent element‑by‑element read of the reference disclosures. (ii) Inventor lists for US 7,554,404 B2 and US 7,683,851 B2 are given with the confidence noted and should be confirmed on the face of those patents. (iii) The k3<k1,k2 limitation's dependence on layout (claims 7–10) means any anticipation theory would also require the reference to disclose the stacked‑layer geometry; none of the cited references does.

I'll ground this analysis in the actual prior-art references of record and their content before assessing the § 103 case.

I have strong grounding now. Let me pull two more pieces: the Broadcom stacked/multi-tap transformer balun art (relevant to the layout and coupling-coefficient limitations) and the full US7683851 disclosure.

Obviousness Analysis — U.S. Patent No. 8,279,018 B1 under 35 U.S.C. § 103

Analyst note / scope: This builds on the earlier-generated summary and litigation sections. Everything below treats the patent text as authoritative and uses the Prior Art section of the record (the three cited U.S. patents and four NPL citations), plus closely-related art that the cited patents expressly cross-reference. Web-search snippets were used to confirm the substance of those references and are quoted where relevant. I was cut off from further tool calls mid-session, so I could not pull the full specification text of US 7,683,851 or the drawing sheets of US 7,209,727; statements about those documents rest on the retrieved portions quoted below and are flagged where figure-level detail is required.

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1. Legal framework applied

• Governing standard: Graham v. John Deere Co., 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007); MPEP § 2141–2143.
• Effective filing date for § 102/§ 103 art: 2009-03-16 (provisional 61/160,514, "Balun Design"). Art must therefore predate March 2009 (or qualify under § 102(e) by earlier filing).
• KSR rationales available against these claims:
  • (A) combining known elements per known methods to yield predictable results;
  • (B) simple substitution of one known element for another;
  • (C) use of a known technique to improve similar devices in the same way;
  • (F) "obvious to try" — a finite number of identified, predictable solutions in a design space (winding geometry vs. coupling coefficient).
• Level of ordinary skill: a B.S./M.S. in EE with 3–5 years of RFIC/CMOS transceiver design experience as of 2009 — capable of designing on-chip transformers/baluns, calculating coupling coefficients, and choosing metal layers for windings as routine design work.

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2. The prior art of record — what each reference actually teaches

2.1 US 7,209,727 B2 — Castaneda et al., Broadcom ("Integrated circuit radio front-end architecture")

🔗 https://patents.google.com/patent/[US7209727B2](/patent/US7209727B2)/en

This is the single most on-point structural reference. Its stated purpose is the same problem the '018 patent solves — that a PA and an LNA have different balun requirements, so "separate baluns are used to support an LNA and a PA," which "requires too large a die area." Its solution:

"Such an integrated RF front-end architecture includes a multi-tap balun, a low noise amplifier and a power amplifier core. The multi-tap balun includes a single-ended primary winding and a symmetrical multi-tap secondary winding, wherein the single-ended primary winding is operably coupled to an antenna. The low noise amplifier is coupled to a first set of taps of the symmetrical multi-tap secondary winding. The power amplifier core … is coupled to a second set of taps…"

Critically, US 7,209,727 also discloses the impedance-compensation concept that appears in the '018 dependent claims:

"[T]he low noise amplifier having an input impedance that is substantially the same in both the low noise amplifier on state and the low noise amplifier off state."

And it frames the differing requirements in exactly the terms of the '018 spec: LNA balun = "high voltage gain with a low noise figure"; PA balun = "support large ac and dc currents, which requires a large track width." It also cross-references Broadcom's on-chip transformer balun work (Ser. No. 10/055,425 → US 6,801,114) and integrated circuit LNA work (Ser. No. 10/128,193).

2.2 US 7,683,851 B2 — Broadcom ("Method and system for using a single transformer for FM transmit and FM receive functions")

🔗 https://uspto.report/patent/grant/[7683851](/patent/7683851)

This is the closest single reference to claim 1's structural core. Its FIG. 2A duplex transformer comprises one primary and two secondary windings:

"[T]here is shown an antenna 202, an RF transformer 204, a power amplifier 206, a low-noise amplifier 208… The RF transformer 204 may comprise a primary winding 214 and secondary windings 216 and 218."

"When a signal is received at antenna 202, it may be fed to the primary winding 214 … The low-noise amplifier 208 may be coupled to the secondary winding 218…"

"The output of the power amplifier 206 may be coupled to the secondary winding 216."

"For transmission purposes, the number of effective windings L2-1 of the secondary winding 216 may generally be desired lower than L2-2 because a lower impedance for transmission may be desirable… [S]ince the received signal at the antenna 202 may be a low-energy signal, the secondary winding 218 may comprise L2-2 > L1 windings. A larger number of windings for the secondary winding 218 may increase the impedance and may lead to a higher voltage gain."

It also expressly contemplates TDD and simultaneous (full-duplex) operation:

"In some instances, reception and transmission may occur in a time division duplex (TDD) mode… In another embodiment of the invention, transmission and reception may take place simultaneously."

So the antenna winding → PA winding and antenna winding → LNA winding, with separately designed turn counts and hence separately designed impedance transformations, is squarely disclosed. This reference alone prefigures the '018 patent's stated advantages.

2.3 US 7,554,404 B2 — Broadcom ("Method and system for a low noise amplifier with tolerance to large inputs")

🔗 https://patents.google.com/patent/[US7554404B2](/patent/US7554404B2)/en

Directed to keeping an on-chip LNA alive (rather than switching it out) during high-power transmit events:

"Aspects of the method may comprise providing an individual current source for each input transistor to a low noise amplifier (LNA), wherein the individual current sources may be isolated from each other when the LNA is turned off. Isolating the individual current sources may be accomplished, for example, by using a switch."

It also motivates co-integrating PA and LNA ("the LNAs and power amplifiers may be placed on separate chips. This may increase the chip count…") and describes switching the LNA into/out of a defined state in the presence of large PA swings. This is the natural secondary reference for the switch + capacitor receive-circuit limitations of claims 11–13.

2.4 B. Marholev et al., "A Single-Chip Bluetooth EDR Device in 0.13 μm CMOS," ISSCC 2007, pp. 558–559 (DOI 10.1109/ISSCC.2007.373542)

🔗 https://doi.org/10.1109/ISSCC.2007.373542

The NPL reference of record (Broadcom, Irvine). Directly relevant passages:

"[A] configurable transformer circuit which is shared between the receiver and transmitter… The RF front-end transformer, LNA, and PA are depicted in Fig. 31.1.2. The TX/RX transformer circuit couples the signal from its primary to its secondary side which connects directly to the inputs of the LNA and outputs of the PA. Depending on the mode of the NMOS switches controlled by EN_P and EN_N, either RFN or RFP can be tied to ground… the TX/RX switch functionality is inherent in the topology by having either the PA or LNA enabled at any given time."

"The transformer and its load are forming a parallel resonance circuit and are designed to have a real impedance of about 50 Ω at the primary terminals around the operating frequency. When the LNA or PA are off they provide a high-impedance load at the secondary side of the transformer."

"[A]s the impedance matching is defined by the transformer circuit, the input capacitance of the LNA is considered as a part of the total capacitance needed for the transformer to resonate at the desired frequency."

That last sentence is essentially the claim 14/15 "resonate at the operating frequency" concept, and the EN_P/EN_N switch description is the claim 11/12 switch concept.

2.5 Art cross-referenced by, or closely adjacent to, the record (usable, but verify)

• US 6,801,114 (Broadcom, "Integrated radio having on-chip transformer balun," Ser. No. 10/055,425) — expressly cross-referenced inside US 7,209,727: "primary and secondary metal windings at separate layer interfaces… have high coupling coefficients." Teaches the layered-winding layout behind '018 claims 7–9.
• US 6,707,367 / US 7,088,214 (Broadcom, "On-chip multiple tap transformer and inductor") — "The 1st winding is on a 1st layer … The 1st and 2nd portions of the 2nd winding are on a 2nd layer." Teaches the "one winding on one layer, other windings on a lower layer" architecture.
• US 8,325,752 / US 2010/0027568 (TI, Rajendran et al., filed 2008-07-29 — pre-dates the '018 priority) — explicitly analyzes the Marholev scheme and other T/R-sharing schemes and criticizes them for two inductors / two LC tanks; § 102(e) art for the switching aspects.
• US 2011/0227663 / US 8,558,635 (ETRI, "3-way balun for planar-type double balanced mixer," priority 2008-11-19) — a three-winding balun predating the '018 priority. It appears in the record only as a forward citation, but its priority date makes it candidate § 102(e) art for the "three magnetically related windings" concept. I have not verified its disclosure in detail — flag for retrieval.

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3. The applicant's own admissions (usable as prior art under KSR / MPEP § 2129)

The specification concedes the state of the art before the invention:

"A balun may be designed with three inductors to allow slight variance in transmit and receive characteristics." (discussing FIG. 3)

"This architecture may achieve the independent impedance transformation in the receiver and antenna, and transmitter and antenna by varying the tapping point of L3 from L2."

"The impedance ratio … may change depending on whether data is being transmitted or received."

These are admissions that (i) three-inductor baluns, (ii) independent TX/RX impedance transformation, and (iii) separately configurable TX/RX characteristics were known. The applicant's only asserted differentiators over the FIG. 3 arrangement are isolation (poor in FIG. 3) and layout flexibility — i.e., precisely the kind of known, incremental improvement that triggers KSR rationales (C) and (D).

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4. Claim 1 — element-by-element mapping

Element 6 nuance: US 7,683,851's two secondary windings are drawn as separate windings 216 and 218. Whether they share a common node (e.g., a center tap to ground) needs checking against FIG. 2A. If they share a ground node, "separate circuit" is still satisfied in the electrical sense the '018 patent uses (no current path between the PA and LNA through the other's winding — see '018: "circuit 422 is not electrically connected to circuit 424 and thus current does not run through an inductor 408c, and vice versa"). Flag: verify FIG. 2A/2B winding topology.

Element 7 — the crux. Two independent lines of attack:

1. Inherency/predictability. The limitation recites relative values only — no numeric bounds. A transformer in which L1 is wound to couple to both L2 and L3, while L2 and L3 are laid out so as not to load one another, necessarily exhibits k3 < k1, k2. The '018 specification itself admits this is a matter of layout: "the coupling between inductor 408b and inductor 408c is low because they are side-by-side," and coupling is "strong" simply because L1 is stacked "on top of" L2 and L3. That is the textbook geometry-dependence of mutual inductance, and both stacking-on-separate-layers and side-by-side placement are taught by US 6,801,114 and US 6,707,367/US 7,088,214, which are cross-referenced by US 7,209,727. Under KSR, "a finite number of identified, predictable solutions" for winding placement — vertical stacking (high k) vs. lateral separation (low k) — makes the claimed coupling profile obvious to try.
2. Motivation from the art. US 7,209,727 and Marholev both identify the T/R isolation problem: US 7,209,727 devotes extensive text to eliminating the T/R switch and to the interaction of PA and LNA on a shared winding; Marholev relies on "the PA or LNA enabled" plus switches, with the off device presenting "a high-impedance load at the secondary side." Reducing k3 is the direct, predictable way to improve isolation between the two paths while keeping each strongly coupled to the antenna winding. Rationales (C) and (D) apply.

Proposed primary combination for claim 1: US 7,683,851 (primary) in view of US 7,209,727 and Marholev ISSCC 2007, optionally further in view of US 6,801,114 / US 6,707,367 for the layered layout. All are analogous art (same field: CMOS RF transceiver front-end transformers/baluns; same problem: serving a PA and an LNA from one antenna coupling network). Three of the four share overlapping inventorship/assignee (Broadcom: Castaneda, Bhatti, Roufoogaran, Rofougaran) — an unusually strong "same field, same problem, same designers" combination story under § 103.

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5. Claim-by-claim obviousness conclusions

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6. Motivation to combine (the § 103 "why")

1. Same field, same problem, same solution space. All principal references address one antenna coupling network serving both a PA and an LNA in a CMOS transceiver. US 7,209,727 states the problem explicitly: PA and LNA "have different balun requirements" and using two baluns "requires too large a die area." The '018 patent restates the identical problem ("having a matching network that is shared does not optimize both transmitter and receiver performance"). KSR rationale (C).
2. The claimed remedy is the art's own remedy. US 7,683,851 solves it by giving the PA and LNA their own secondary windings with different turn counts and different target impedances — which is claims 2 and 4 verbatim. Substituting that duplex transformer for the multi-tap single secondary of US 7,209,727 is a simple substitution of one known element for another yielding predictable results. KSR rationale (B).
3. Isolation was a recognized, quantified goal. Marholev measures switch loss ("about 1 dB … in RX or TX mode") and discusses off-state high impedance; US 7,209,727 discusses eliminating a T/R switch and the PA/LNA interaction on a shared winding. A PHOSITA seeking to improve isolation would predictably reduce mutual coupling between the TX and RX windings — a finite design choice resolved by geometry. KSR rationales (A), (F).
4. Reasonable expectation of success. Every element operates by well-understood transformer theory; there is no new physical principle asserted, no unexpected result reported, and no criticality of numbers (the claim recites only ordering of coupling coefficients). The '018 specification itself presents the layout as an optional design exercise: "Although this method is described, other methods and design[s] may be used. Particular embodiments are not limited to the described design."
5. No teaching away. Marholev's reliance on a single shared transformer with off-state high impedance is an alternative, not a disparagement of separate TX/RX windings — and US 7,683,851 demonstrates the separate-winding approach works.

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7. Where the § 103 case is vulnerable (counter-arguments the applicant/patee could make)

1. The k3 limitation has no express antecedent in the combined art. None of the three cited patents discusses any coupling coefficient numerically or relatively. An examiner/PTAB panel could hold that the applicant was entitled to a patent because the art, while disclosing the topology, does not disclose the coupling-coefficient relationship and does not render it inherent — especially if, in US 7,683,851's duplex transformer, the two secondary windings are adjacent and do couple significantly to each other (which would mean the prior art teaches the opposite of k3 < k1, k2). This is the pivotal factual question. It must be resolved by inspecting US 7,683,851 FIG. 2A/2B (winding geometry and whether they are concentric/interleaved).
2. US 7,209,727 alone teaches toward the applicant's own "FIG. 3" prior art. Its single multi-tap secondary winding is the tapped-winding arrangement the '018 specification criticizes for poor isolation and extra parasitic inductance. If a panel characterizes US 7,209,727 as the closest art, the k3 element and the "first circuit separate from the second circuit" element both become harder to meet, because a multi-tap secondary shares one winding between PA and LNA. The examiner's combination should therefore lead with US 7,683,851, not US 7,209,727, on claim 1. (There is a real tension between the two references that must be reconciled in any rejection.)
3. Claim 14's "simultaneous" full-duplex resonance at one operating frequency. US 7,683,851 affirmatively suggests TX and RX use different frequencies during simultaneous operation, which could be read as teaching away from same-frequency simultaneous resonance. Marholev is a TDD (half-duplex) Bluetooth device. A rejection of claim 14 must supply the full-duplex motivation from elsewhere (e.g., general duplexer/electrical-balance art), and this combination is more vulnerable.
4. Secondary considerations: none known. Per the earlier-generated litigation section, no litigation, ITC action, or PTAB proceeding naming US 8,279,018 was located, so there is no objective-indicia record (no nexus evidence, no copying, no industry praise) either way. Likewise, no known commercial-success evidence. Absence of objective indicia neither helps nor hurts the prima facie case — it simply means the § 103 case turns on the art.

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8. Bottom line

• Claims 2, 3, 4, 13, 17, 18 — strong § 103 rejections. They are met essentially verbatim by US 7,683,851 (separately designed TX/RX winding counts and impedance targets) optionally with US 7,209,727 (LNA input impedance substantially the same on/off). These should not have been allowed without a strong traversal.
• Claims 5–9, 11, 12, 15 — good § 103 rejections using US 7,683,851 + Marholev + US 7,554,404 + the Broadcom layered-winding art (US 6,801,114 / US 6,707,367 / US 7,088,214).
• Claim 1 and claim 16 — rejectable, but only on a carefully built record: US 7,683,851 as primary (three-winding transformer, antenna-coupled primary, separate PA and LNA secondaries, separate circuits) + Marholev (consistent transformer/LNA/PA front end, T/R mode switching) + US 6,801,114 / US 6,707,367 (stacked-layer vs. lateral winding placement controlling coupling). The asserted motivation is isolate the transmit and receive circuits while keeping both strongly coupled to the antenna. Reasonable expectation of success is high because the claim recites only a relative ordering of coupling coefficients with no numerical bounds, and the specification itself attributes the effect to routine choice of winding geometry.
• Claim 10 — largely inherent to claims 7–9; adds little patentable weight.
• Claim 14 — the most defensible dependent claim; a rejection here needs additional duplexer art and may face a teaching-away argument from US 7,683,851's different-frequency simultaneous mode.

Confidence: moderate-to-high for the dependent claims; moderate for independent claims 1/16, pending visual verification of US 7,683,851's secondary-winding topology (the single most important open question). I could not complete retrieval of US 7,683,851's drawing sheets, the ETRI 3-way balun's disclosure, or the full text of US 7,209,727's claims, so those specific points should be confirmed before filing any rejection. No litigation or objective-indicia evidence exists in the record to offset the prior-art case.