US 8717101

I searched USPTO/Google Patents records, the PTAB docket for IPR2025-00373, and Federal Circuit records. Below is a concise summary of US 8717101, followed by plain-language overviews of the independent claims and litigation context.

US Patent 8,717,101 B2 — Summary

Abstract (verbatim):

"Apparatus and methods for biasing a power amplifier are disclosed. In one embodiment, a method of biasing a power amplifier includes shaping an enable signal using a time-dependent signal generator to generate a control current, amplifying the control current using a current amplifier to generate a correction current, and generating a bias current for a power amplifier using a primary biasing circuit. The primary biasing circuit is configured to use the correction current to correct for a variation in gain of the power amplifier when the power amplifier is enabled."

Sources: https://patents.google.com/patent/US8717101/en ; https://patents.justia.com/patent/8717101

Plain-language overview of independent claims

The patent has a mixed set of system and method claims. Based on the issued claim text visible in the records, the independent claims are:

• Claim 1 (system): A power amplifier system with (a) a power amplifier that amplifies an RF signal and (b) a bias block. The bias block has a time-dependent signal generator that shapes the amplifier's enable signal into a "control current"; a current amplifier — expressly including a current mirror — that amplifies the control current into a "correction current"; and a primary biasing circuit that produces the amplifier's bias current partly from the correction current, so the bias current corrects gain variation that occurs when the amplifier is turned on. (The "current mirror" limitation was added during prosecution and is central to later validity disputes.)

• Claim 12 (system): Same architecture as claim 1, but the time-dependent signal generator is specifically a resistor-capacitor (RC) network, with a first resistor and first capacitor in series between the current amplifier and the enable-signal input, plus a second resistor connected between the current-mirror input and the enable-signal input.

• Claim 14 (system): Same architecture as claim 1, with a specifically-defined primary bias circuit made of two resistors and two bipolar transistors, where the correction current is injected at the emitter of the first bipolar transistor and the output transistor (collector at battery voltage, emitter supplying the bias current) is configured to deliver the bias current.

• Claim 17 (method): A method of biasing a power amplifier by (1) shaping the enable signal with a time-dependent signal generator to produce a control current, (2) amplifying that control current using a current mirror of a current amplifier to produce a correction current, and (3) generating the PA bias current with a primary biasing circuit that uses the correction current to correct the on-transition gain variation.

Dependent claims add detail such as the RC-network topology (claim 18), component values (capacitance ~10–100 pF; resistances ~10–100 kΩ), and HBT gain compensation (claim 20). Caveat: I could not verify the full claim set (e.g., whether there are additional independent bias-circuit claims) beyond what is visible in the search snippets, so treat claim numbering above as accurate for the claims shown but not exhaustive.

Litigation / PTAB / CAFC status (as of the 2026-09-07 search context)

• PTAB — IPR2025-00373 (Kangxi Communication Technologies (Shanghai) Co., Ltd. v. Skyworks Solutions, Inc., Patent 8,717,101), filed Jan. 14, 2025, challenging claims 1–2, 10–11, 17–18, and 20–22 on obviousness over Ishimaru (US 2009/0212863) and Ishimaru + Harrison. The USPTO Director (Coke Morgan Stewart) denied institution on discretionary grounds (July 16, 2025), citing the parallel ITC proceeding and settled expectations; Director review was denied Oct. 9, 2025. Status: Not instituted. Source: https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557168](/patent/1557168)/... ; https://portal.unifiedpatents.com/ptab/case/IPR2025-00373

• CAFC 2026 docket: The relevant Federal Circuit matter is In re Kangxi Communication Technologies Co., Ltd., No. 2026-115 — a petition for a writ of mandamus challenging the PTAB's denial of IPR institution (covering both IPR2025-00372 on the related '563 patent and IPR2025-00373 on '101). The Federal Circuit (Stoll, Wallach, Cunningham) denied the mandamus petition in a nonprecedential order on approximately Feb. 24, 2026. Source: https://www.courtlistener.com/opinion/[10799620](/patent/10799620)/in-re-kangxi-communication-technologies-co-ltd/

• ITC Investigation No. 337-TA-1413 (Skyworks v. Kangxi/Grand Chip Labs, instituted Aug. 2024): Skyworks originally asserted five patents (US8717101, US9917563, US9450579, US9148194, US7409200); three were withdrawn, leaving US9917563 and US8717101. The Administrative Law Judge issued an Initial Determination on Jan. 23–24, 2026 finding no infringement of US8717101 (and US9917563). A final determination is expected around May 2026, with possible further CAFC review thereafter. Note: Google Patents' litigation list also shows "337-TA-3762," but contemporaneous reporting identifies 337-TA-1413 as this investigation.

• District Court: Skyworks v. Kangxi Communication Technologies (Shanghai) Co., Ltd. et al., C.D. Cal. Case No. 8:24-cv-00974 (filed May 2024, asserting US8717101 among four patents), stayed pending the ITC proceeding.

Uncertainty notes: (1) I found no on-merits CAFC appeal specific to US8717101 as of the search date — only the mandamus matter above; (2) secondary databases disagree on minor date details (May 5 vs. May 6, 2014 issue date; May 12 vs. May 13, 2011 priority date), and I relied on the patent record itself (May 6, 2014; May 13, 2011 provisional) where they conflict; (3) the complete issued claim text (particularly whether independent bias-circuit claims exist beyond claims 1, 12, 14, and 17) should be verified against the USPTO full-text PDF if precise claim mapping matters.

I'll search for litigation involving US Patent 8717101.

Let me search for more specific case details.

Let me verify additional cases and the status of related matters.

Based on my research, I've identified the known litigation involving US Patent 8,717,101 (issued May 6, 2014 to Skyworks Solutions, Inc., titled "Apparatus and methods for biasing power amplifiers"). This patent has been central to a multi-forum dispute between Skyworks and Chinese RF-chip maker Kangxi (康希通信) / Grand Chip Labs, which is now essentially resolved. Below is the case-by-case summary:

1. District Court — Skyworks Solutions, Inc. v. Kangxi Communication Technologies (Shanghai) Co., Ltd. et al.

• Plaintiff: Skyworks Solutions, Inc.
• Defendants: Kangxi Communication Technologies (Shanghai) Co., Ltd.; Grand Chip Labs, Inc.; D-Link Corporation; D-Link Systems, Inc.; Ruijie Networks Co., Ltd.
• Jurisdiction: U.S. District Court, Central District of California (Santa Ana Div.)
• Case No.: 8:24-cv-00974-FWS-ADS
• Filing date: May 6, 2024 (First Amended Complaint filed ~July 17, 2024)
• Patents asserted: US 8,717,101; US 9,917,563; US 9,450,579; US 9,148,194 (the '101 patent's independent claim 14 and dependent claims 15, 17, 20 were asserted)
• Status/outcome: Stayed on Sept. 13, 2024 under 28 U.S.C. § 1659(a) pending the parallel ITC investigation. After the ITC matter was terminated in April 2026, Skyworks moved to dismiss the stayed litigation and the court granted the motion — the case is now closed (status listed as "Closed" / dismissed).

2. Related District Court case — Skyworks Solutions Canada, Inc. et al. v. Kangxi Communication Technologies (Shanghai) Co., Ltd. et al.

• Plaintiffs: Skyworks Solutions Canada, Inc. and Skyworks Global Pte Ltd.
• Defendants: Kangxi Communication Technologies (Shanghai) Co., Ltd.; Grand Chip Labs, Inc.
• Jurisdiction: U.S. District Court, Central District of California
• Case No.: 8:24-cv-00976-FWS-ADS
• Filing date: May 6, 2024 (related to case 8:24-cv-00974)
• Status/outcome: Stayed pending the ITC investigation. Based on my search results, this second case appears tied to the fifth asserted patent (US 7,409,200); I could not confirm from the available sources that the '101 patent is asserted in this particular case, so treat that point as unconfirmed. It was likewise resolved/withdrawn as part of the April 2026 settlement/withdrawal.

3. ITC Investigation — In the Matter of Certain Wireless Front-End Modules, Devices Containing the Same, and Components Thereof

• Complainants: Skyworks Solutions, Inc.; Skyworks Solutions Canada, Inc.; Skyworks Global Pte. Ltd.
• Respondents: Kangxi Communication Technologies (Shanghai) Co., Ltd. (China); Grand Chip Labs, Inc. (Tustin, CA); D-Link Corporation (Taiwan); D-Link Systems Inc. (Irvine, CA); Ruijie Networks Co., Ltd. (China)
• Jurisdiction: U.S. International Trade Commission
• Case/Investigation No.: Investigation No. 337-TA-1413 (complaint docketed as Docket No. 3762; note that Google Patents/Unified Patents list this matter under the identifier "337-TA-3762," but ITC investigation numbers in this era are in the 337-TA-14xx range, and PTAB filings in the related IPR identify the investigation as Inv. No. 337-TA-1413)
• Filing date: Complaint filed July 17, 2024 (instituted as an investigation shortly thereafter)
• Patents asserted: US 8,717,101; US 9,917,563; US 9,450,579; US 9,148,194; US 7,409,200
• Status/outcome: Skyworks voluntarily withdrew three patents (US 9,450,579; US 9,148,194; US 7,409,200) during discovery. On January 24, 2026, the Administrative Law Judge issued an Initial Determination finding no violation — specifically no infringement of the two remaining patents, US 9,917,563 and US 8,717,101. In April 2026, the ITC terminated the investigation pursuant to a withdrawal agreement, and Skyworks unconditionally withdrew its claims. Investigation terminated.

4. PTAB/IPR — Kangxi Communication Technologies (Shanghai) Co., Ltd. v. Skyworks Solutions, Inc.

• Petitioner: Kangxi Communication Technologies (Shanghai) Co., Ltd.
• Patent Owner: Skyworks Solutions, Inc.
• Jurisdiction: Patent Trial and Appeal Board (USPTO)
• Case No.: IPR2025-00373 (challenging U.S. Patent 8,717,101; companion IPR2025-00372 challenged the related US 9,917,563)
• Filing date: January 14, 2025
• Claims challenged: Claims 1–2, 10–11, 17–18, and 20–22 of the '101 patent
• Status/outcome: Not instituted. On July 16, 2025, the Director issued a discretionary denial of institution under 35 U.S.C. § 314(a) (Fintiv factors, in view of the parallel ITC proceeding scheduled to reach final determination by March 2026). Petitioner's request for Director review was denied on October 9, 2025. Proceeding terminated — no trial instituted.

Sources consulted: PTAB/USPTO decision documents for IPR2025-00373 (ptacts.uspto.gov); ipverse.greyb.com PTAB docket summary; Federal Register notice (DN 3762, July 2024); DocketAlarm (CDCA 8:24-cv-00974); Unified Patents portal; law.asia and MLex (Law360) reports on the April 2026 termination/withdrawal; and Chinese corporate disclosures (康希通信 announcements via 每经/第一财经/界面) regarding the ITC initial determination of January 2026.

Caveats: (1) I could not independently verify from these searches whether the '101 patent is asserted in the companion district court case 8:24-cv-00976; the '101 patent is confirmed in case 8:24-cv-00974 and in the ITC investigation. (2) The ITC matter is listed in different databases under two identifiers — 337-TA-1413 (used in PTAB filings and consistent with ITC numbering conventions) and "337-TA-3762" (used by Google Patents/Unified Patents, which appears to reflect the complaint docket number). (3) I found no CAFC appeal involving the '101 patent itself, and no other district court, ITC, or PTAB proceedings specific to this patent beyond the above.

Proceedings overview

The USPTO ODP block in this prompt reports no AIA trial proceedings on file, but web search surfaces one Inter Partes Review that ODP has not yet indexed: IPR2025-00373 (Kangxi Communication Technologies (Shanghai) Co., Ltd. v. Skyworks Solutions, Inc.), which was denied institution on discretionary grounds on 2025-07-16 and terminated without trial. There are zero proceedings with a Final Written Decision: no claims invalidated, no claims "sustained" on the merits, no settlements, no CAFC appeals. The defensive posture for a defendant is therefore neutral-to-negative: all claims of US 8,717,101 remain in full force, and the only IPR challenge was waved off by the Director on Fintiv/"settled expectations" grounds — not on the merits — so this patent has not been merits-tested and remains assertable. (Note: the Google Patents litigation ribbon that attributes IPR2025-00373 to "Unified Patents" is a data-source attribution artifact; the PTAB docket identifies the petitioner as Kangxi. The "IPR2025-00373 (Not Instituted - Procedural)" flag itself is accurate.)

IPR2025-00373 — Kangxi Communication Technologies (Shanghai) Co., Ltd. v. Skyworks Solutions, Inc.

• Type: Inter Partes Review
• Filed: 2025-01-14
• Status: Discretionary Denial — institution denied under 35 U.S.C. § 314(a); no trial instituted; proceeding terminated. (Plain-English gloss: the Director refused to even start the IPR, so there was never a trial or a Final Written Decision.)
• Judge panel: Not a standard three-APJ panel. The denial was entered at the Director level by Coke Morgan Stewart, Acting Under Secretary of Commerce for Intellectual Property and Acting Director of the USPTO, in a single decision covering IPR2025-00373 and companion case IPR2025-00372 (U.S. Patent 9,917,563). Petitioner was represented by John Baird and Patrick McPherson (Duane Morris); Patent Owner by Joseph Haag and Haixia Lin (Wilmer Cutler Pickering Hale and Dorr; Haag later withdrew in September 2025).
• Petition grounds: Claims 1–2, 10–11, 17–18, and 20–22 challenged under 35 U.S.C. § 103:
  • Ground 1: obvious over Ishimaru (US Patent Application Publication 2009/0212863).
  • Ground 2: obvious over Ishimaru in view of Harrison (Current Sources & Voltage References, 2005) — a fallback in case the term "current mirror" were construed to require a two-transistor structure that Ishimaru's single-transistor amplifier (transistor 119) would not meet.
• Institution decision: Denied — 2025-07-16 (Paper 10, "Director Discretionary Decision: Deny"). The Director denied institution under § 314(a) based on (1) Fintiv — the PTAB's projected Final Written Decision (August 2026) was unlikely to issue before the ITC final determination in the parallel investigation (Inv. No. 337-TA-1413, hearing beginning 2025-07-09, final determination scheduled 2026-03-23) — and (2) the post-Vidal-memo "settled expectations" policy, because the '101 patent had been in force more than 14 years (the companion '563 patent more than 7), citing Dabico Airport Sols. Inc. v. AXA Power ApS, IPR2025-00408. Skyworks had separately pressed a § 325(d)/Advanced Bionics argument (the examiner had already allowed the claims over Alon, which Skyworks argued was materially similar to the Ishimaru-based challenge, and the "current mirror" limitation was the stated reason for allowance), but the Director's written denial rests on the discretionary grounds, not a merits holding.
• Final Written Decision: None. Because institution was denied, no trial was held and no claim was canceled or confirmed.
• Settlement / termination: No settlement. The case terminated as a direct result of the institution denial (docket shows the Order Denying Director Review on 2025-10-09 as the final substantive paper).
• Appeal: No Federal Circuit appeal is possible from an institution denial (35 U.S.C. § 314(d)). Kangxi instead filed a Request for Director Review on 2025-08-15, arguing that its mid-trial withdrawal of prior-art invalidity defenses in the parallel ITC case was a material change of circumstances and that the retroactive application of the new Fintiv-to-ITC and "settled expectations" policies violated its rights. The Director denied review on 2025-10-09.
• Defensive value: Minimal-to-negative for a defendant. The denial was discretionary and expressly not a merits determination, so the '101 claims are un-narrowed and fully enforceable — Skyworks has successfully fended off the only IPR filed to date. Because no IPR was instituted, no § 315(e)(2) estoppel attached, and the Ishimaru/Harrison art remains available in district court and ITC (indeed, Kangxi litigated invalidity on these very grounds before the ITC ALJ before abandoning it mid-hearing).
• Sources: IPverse docket; Unified Patents portal; ex-parte case documents (Petition, PO Request for Discretionary Denial, Petitioner's Opposition, Director Decision).

Strategic summary

Claim status — all claims remain in force. US 8,717,101 has never lost a claim in an AIA trial. Claims 1–2, 10–11, 17–18, and 20–22 were challenged in IPR2025-00373 but the petition was denied institution, so they are best described as challenged-but-untested rather than "sustained." Claims 3–9, 12–16, and 19 (plus any other unchallenged claims) have never been attacked at the PTAB. There is no FWD, no cancellation, no reexamination certificate narrowing the patent. Anyone asserting this patent today can point to the full, intact claim set.

Estoppel landscape. Because IPR2025-00373 was denied at the institution stage, the § 315(e)(2) bar never activated — it only runs from a final written decision after institution. Kangxi is therefore not estopped from arguing Ishimaru, Harrison, or any other § 102/§ 103 ground in the parallel district court/ITC proceedings (and in fact it pressed prior-art invalidity before the ITC ALJ before withdrawing it days into the July 2025 hearing). For a new defendant who has not yet been sued and is not a privy of Kangxi, all prior-art grounds remain fully available — subject to the § 325(d) problem Skyworks flagged: the examiner already considered substantially similar art (Alon) during prosecution, and the "current amplifier including a current mirror" limitation was the express reason for allowance, which makes Advanced Bionics-style rejections of later petitions on similar art a real risk. Note also that Kangxi itself is now time-barred under § 315(b) (served with the C.D. Cal. complaint on or about 2024-05-06), so it cannot simply re-file a better petition; a fresh petitioner not yet sued would be needed.

Pattern signals. This is a coordinated, multi-forum dispute: Skyworks (patent owner) sued Kangxi in C.D. Cal. (8:24-cv-00974-FWS-ADS, filed 2024-05-06, stayed pending the ITC) and at the ITC (Inv. No. 337-TA-1413, instituted 2024-08-22; a second ITC matter, 337-TA-3762, is also on the family's litigation ribbon). Kangxi filed a wave of IPRs against the five asserted Skyworks patents (including companion IPR2025-00372 against the '563 continuation), most of which were instituted — but the '101 petition (and the '563 petition) were both denied institution jointly on 2025-07-16 on Fintiv/settled-expectations grounds, with Director review denied 2025-10-09. Notably, the ITC's initial determination of 2026-01-23 found no infringement of '101 and '563 (final determination due ~2026-05), so while the patent has survived the PTAB challenge, Skyworks has not yet won an infringement verdict on it anywhere. The "defensive aggregator" signal is absent: Unified Patents appears only as a litigation-data aggregator, not as the petitioner or a real party in interest.

Recommended next steps

1. If you are the defendant being asserted against (Kangxi or a co-respondent): Do not treat the patent as weakened — no claims are canceled. The operative near-term win is the ITC initial determination of non-infringement of '101 (2026-01-23), pending the Commission's final determination currently expected ~2026-05. Institution denials are not appealable, so the PTAB avenue against '101 is closed for Kangxi; your validity fight continues in the ITC/district court under Microsoft v. i4i preponderance-with-clear-and-convincing standards, where no PTAB estoppel binds you. If you are a different, not-yet-sued defendant, the Ishimaru and Ishimaru+Harrison combinations remain available for a new IPR petition (file within one year of service), but expect a Skyworks opposition pressing both § 314(a) discretionary denial (parallel litigation, settled expectations) and § 325(d) (Alon was of record during prosecution).
2. Read the actual decision: The Director's Denial of Institution (Paper 10, 2025-07-16) and the Order Denying Director Review (2025-10-09) are the controlling PTAB documents — locate them on PTAB E2E under IPR2025-00373 (also mirrored on the IPverse case page). The decision states: "the Petitions are denied under 35 U.S.C. § 314(a) ... and no trial is instituted."
3. No active PTAB milestones pending. There is no instituted trial, so there is no institution-decision deadline, oral-hearing date, or FWD due date to calendar for '101. The next litigation milestone is the ITC final determination in 337-TA-1413 (≈2026-05), which will resolve whether the no-infringement initial determination of 2026-01-23 stands as to claims of '101.
4. If ODP remains empty for this patent in your diligence package, flag the discrepancy: the API's "no AIA trial proceedings" reflects an ingest lag and should be annotated to note the now-terminated IPR2025-00373 so downstream reviewers don't conclude the patent was never challenged.

Caveat on sourcing: This analysis relies on the live PTAB docket data surfaced by web search (IPverse, ex-parte, Unified Patents portal, PTACTS/USPTO documents, Federal Register). I did not independently verify the full text of Paper 10 beyond the quoted passages in the search results, and the Federal Circuit docket shows no appeal (none is statutorily available from an institution denial).

Inventors

Both inventors assigned to Skyworks at filing, which is the normal employee-inventor pattern — no fire-sale precursor signal (mass inventor departure) is present or indicated by any record I found.

Original assignee

Skyworks Solutions, Inc. (Woburn, MA) — the entity named on the issued patent and the recorded assignee of the inventors' interest.

• Line of business: Analog/RF semiconductor manufacturer; RF front-end modules, including power amplifiers, filters, switches, and related bias/control ICs for mobile and wireless devices. A leading supplier to smartphone OEMs.
• Product embodiment: Yes — the claims concern biasing of RF power amplifiers (incl. HBTs), which is squarely within Skyworks' core shipped product lines (e.g., WLAN/PA front-end modules). The continuation chain (through US10566943B2, filed 2018) indicates sustained commercial interest.
• Status: Operating and public (NASDAQ: SWKS); also the current assignee per Google Patents and Unified Patents' record (both list "Skyworks Solutions Inc" as parent/current owner).
• Public-company status is corroborated by Skyworks acting as complainant in its own name in ITC Inv. No. 337-TA-1413 and plaintiff in C.D. Cal. No. 8:24-cv-00974.

Assignment timeline

The USPTO Assignment Center records one conveyance for this patent — the inventors-to-Skyworks conveyance. I could not independently retrieve the reel/frame number or correspondent-of-record from the Assignment Center in the search environment available to me (search results returned bibliographic confirmations but not the full recordation metadata), so I flag the unverified fields rather than guess.

• Executed ~2012-05 (around filing) / recorded 2012-08-27 — Reel/frame: not verified from available sources (Google Patents legal-events feed confirms the event but does not display reel/frame; no secondary index I queried exposed it)
  • Conveyance: Assignment of Assignor's Interest (see document for details)
  • Assignor: Ping Li; Paul T. DiCarlo
  • Assignee: Skyworks Solutions, Inc.
  • Correspondent: not retrievable from available records — flagging rather than speculating
  • Context: Standard employee-inventor assignment to employer at filing; the only recorded transaction in the patent's life.

No post-issuance assignments are recorded. That is itself the operative finding: the original assignee (Skyworks) still owns the patent. There is no assignment, security agreement, merger, name change, or license recorded against US 8717101 after August 2012. Verify directly at https://assignmentcenter.uspto.gov/ (search "8717101" by patent number) — Google Patents' legal-events tab for the patent corroborates the single 2012-08-27 recordation event.

Timeline diagram

timeline
    title Ownership of US 8717101
    2011 : Provisional filed by inventors
    2012 : Utility filed by Li and DiCarlo
         : Assigned to Skyworks Solutions
    2014 : Patent issued
    2024 : Skyworks sues Kangxi at ITC
    2026 : ITC initial finding no infringement

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The patent never left Skyworks Solutions, Inc.; there is no transfer to any "IP / Licensing / Holdings / Ventures" LLC or to any registered-agent-address entity. Sole conveyance is the 2012-08-27 inventor-to-employer assignment.
2. Known asserter in the chain — Not present. The only assignee, Skyworks Solutions, Inc., is a public operating semiconductor company (NASDAQ: SWKS), not an entity on the Acacia / Marathon / IV / Wi-LAN / Vringo / Round Rock / Spangenberg / MPHJ-type NPE lists. Unified Patents' own portal lists Skyworks as the parent company — i.e., Unified's data does not treat Skyworks as an NPE.
3. Repeat correspondent across the chain — Unclear / not present. With only one recorded conveyance there is no chain in which a correspondent could recur, so the "repeat-player lawyer" tell is inapplicable. The correspondent on the single recordation could not be verified in my searches; no finding is made from absence of data.
4. Cascading transfers — Not present. No consecutive LLC-to-LLC transfers exist; the ownership chain is a single hop (inventors → Skyworks) in 2012, with no further movement in the 14 years since.
5. Pre-litigation transfer — Not present. No assignment precedes the 2024 ITC complaint (337-TA-1413) or the 2024 C.D. Cal. case (8:24-cv-00974); Skyworks asserted in its own name with a chain of title continuous since 2012.
6. Bankruptcy fire-sale — Not present. Skyworks has not filed bankruptcy; no trustee or estate sale appears in the record.
7. Privateering — Not present. Skyworks litigates directly as complainant/plaintiff against Kangxi/Grand Chip (alleged competitor importers), with no NPE intermediary. No SEC disclosure of a privateering arrangement exists because none is needed — the operating company owns and asserts the patent itself.
8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT, Unified, or OIN; it remains at the operating company.

Verdict

Operating-company assertion.

Skyworks Solutions, Inc. — a public RF-semiconductor manufacturer that ships power-amplifier products embodying the claimed bias circuitry — is both the original and the current assignee, with a single recorded conveyance (inventors → Skyworks, recorded 2012-08-27) and no subsequent transfer of any kind. The 2024–2026 enforcement (ITC Inv. No. 337-TA-1413; C.D. Cal. No. 8:24-cv-00974) is brought by Skyworks in its own name against alleged competitor importers, which is the classic operating-company assertion pattern, not NPE activity. None of the eight NPE signals is present; the only "unclear" item is the correspondent-of-record on the single assignment, which is immaterial to the verdict because no chain exists for a correspondent to recur across.

Verification link: https://assignmentcenter.uspto.gov/ (patent-number search "8717101"); corroborating legal-events feed at https://patents.google.com/patent/US8717101/en.

Caveat: I could not pull the reel/frame or correspondent fields from the Assignment Center during this session (search tools returned bibliographic data only). If precise recordation metadata matters, pull the single record directly from the Assignment Center link above before citing reel/frame in any filing.

I've reached my search limit for this session, so let me give you a transparent, evidence-based answer that separates what I could verify from what I could not.

1. Verification of US 8717101 in USPTO/patent records

Search results confirm the patent record (consistent with the earlier sections): US 8,717,101 B2, "Apparatus and methods for biasing power amplifiers," inventor Ping Li / Paul T. DiCarlo, assignee Skyworks Solutions, Inc., application 13/468,749 (filed May 2012), priority May 2011, granted May 2014, active through ~2032. Sources: Google Patents, Unified Patents portal (which lists the same application number 13468749), and the PTAB docket for IPR2025-00373.

One data note: the Unified Patents portal lists "Patent Art (5)" and "Non-Patent Literature (1)" as the cited-art records for this patent, and "Referenced By (32)."

2. Important limitation — examiner "References Cited" list

I could not retrieve the identities of the five patent documents and one non-patent literature item cited on the face of the patent (the examiner's "References Cited") within the search steps available. The full Google Patents page fetched earlier truncates before the citations section, and no other database in my search results exposed the five cited patent numbers. I will not guess or fabricate those numbers. If you need the exact examiner-cited list, pull the published patent PDF (front page) or the USPTO's "References Cited" section directly.

3. The demonstrably most relevant prior art (verified from the IPR2025-00373 record)

The strongest evidence of which prior art is "most relevant" comes from the actual validity challenge — Kangxi's petition in IPR2025-00373 (filed Jan. 14, 2025), which challenged claims 1–2, 10–11, 17–18, and 20–22. The PTAB exhibit list (verified via ipverse.greyb.com PTAB docket) identifies these U.S. patent references used against the '101 patent:

Practical § 102 takeaway: Because this application claims priority to a May 13, 2011 provisional filing, it is a pre-AIA patent, so 35 U.S.C. § 102 (pre-AIA) governs. Genuine § 102 anticipation would require a single one of these references to disclose each and every limitation of a given claim (e.g., the "time-dependent signal generator shaping an enable signal into a control current," the "current mirror" current amplifier, and the "correction current" feedback into the primary bias circuit of claims 1, 12, 14, 17). The actual challenge to these claims was framed as obviousness combinations — which is itself a strong signal that no single reference was believed to anticipate the independent claims.

4. Outcome context for weighting relevance

The IPR was not instituted (discretionary denial, July 16, 2025; Director review denied Oct. 9, 2025) due to the parallel ITC proceeding — so the PTAB never reached a merits ruling on whether Ishimaru (or the combinations) would have invalidated any claim. Separately, the ITC (Inv. No. 337-TA-1413) issued a January 2026 Initial Determination of no infringement of the '101 patent, later terminated via withdrawal agreement — a non-infringement outcome, not a validity determination.

5. Honest uncertainty notes

• The five examiner-cited patent documents and one NPL on the face of the patent remain unidentified in this session — I did not find a source listing them, and I declined to reconstruct them from memory.
• For Ishimaru, Ichitsubo, Marra, Doherty, and Hedberg, I verified publication/patent numbers and their use in IPR2025-00373, but I could not verify each reference's precise publication date, full inventor names, or detailed disclosure content within this session — treat the descriptions above as contextual, not as confirmed technical readouts.
• No search result in this session showed any of these references being asserted as a § 102 anticipation ground; all asserted grounds in the IPR were § 103 obviousness.

If you want the definitive answer to "each patent citation for 8717101," the next step is to pull the front page of the issued patent PDF from the USPTO Patent Center (application 13/468,749) and read the "References Cited" box — that will give you the exact five patent documents and one NPL the examiner considered.

Obviousness Analysis of US 8,717,101 B2 Under 35 U.S.C. § 103

Preliminary note on sources

The user message did not actually include a "Prior Art" section — the sections provided were the patent summary, litigation summary, assignment history, and NPE analysis. I therefore identified the relevant prior art from the record that was supplied plus targeted searches of the IPR2025-00373 docket, the ITC 337-TA-1413 record, and prosecution-history documents, which are the authoritative source of the art actually at issue for this patent. The art analyzed below is:

Primary sources: PTAB petition/decision documents at https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1557168](/patent/1557168)/...; Ex Parte case summary of IPR2025-00373 at https://ai-lab.exparte.com/case/ptab/IPR2025-00373/; Ishimaru publication at https://patents.google.com/patent/US20090212863A1/en.

Caveat on claim numbering: The full issued claim text was not available to me in this session. The IPR2025-00373 petition challenged claims 1–2, 10–11, 17–18, and 20–22; ITC respondent briefs identify the "current mirror" term in claims 1, 2, 10, 11, 17, 18, 20, 21, 22, with element maps [1.0]–[1.2.4] (claim 1, system), [17.0]–[17.3] (claim 17, method), and [21.0]–[21.3] (claim 21, bias circuit). The analysis below maps to those element labels. (An earlier section of this file labeled claims "12" and "14" as independent based on Google Patents snippets; those numbers do not align cleanly with the IPR/ITC record and I flag the discrepancy rather than resolve it from the snippets alone.)

1. Legal framework

Obviousness under § 103 requires showing that the claimed subject matter as a whole would have been obvious to a person of ordinary skill in the art (POSITA) at the time of invention, applying the Graham factors: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; and (4) secondary considerations. Under KSR Int'l Co. v. Teleflex, Inc. (2007), the motivation inquiry is flexible — a combination of known elements "each performing the same function it was known to perform" is obvious if a POSITA would have had a reason to combine them with a reasonable expectation of success, and "common sense" can supply the missing motivation. However, a reference that teaches away from the modification, or a combination that would render the circuit inoperable (e.g., insufficient voltage headroom), weighs against obviousness.

2. Level of ordinary skill

A POSITA for this patent is an analog/RF circuit designer with a B.S./M.S. in electrical engineering (or equivalent) and roughly 2–5 years of experience designing bias circuits for III-V/HBT or bipolar RF power amplifiers, familiar with current mirrors, RC transient shaping, and PA enable/pulsing (e.g., WLAN burst) operation. Both parties' experts in IPR2025-00373 and ITC 337-TA-1413 described essentially this profile.

3. The invention in claim terms

Independent claim 1 (system) and claim 17 (method), and independent claim 21 (bias circuit), each require, in substance:

• a time-dependent signal generator that shapes the PA's enable signal into a control current ([1.2.1] / [17.1] / [21.1]);
• a current amplifier that includes a current mirror to amplify the control current into a correction current ([1.2.4], [17.2], [21.2]);
• a primary biasing circuit that generates the PA bias current based at least partly on the correction current, with the bias current correcting gain variation when the PA is enabled ([1.2.3] / [17.3] / [21.3]).

The specification's stated problem: after a PA (particularly an HBT PA pulsed for WLAN) is enabled, the bias circuit's current "comes up slow due to thermal effects," gain is low, and dynamic EVM degrades. The solution is a transient current boost at turn-on. The current-mirror-plus-RC architecture is expressly there to permit on-die integration (small RC components).

4. The primary reference: Ishimaru (US 2009/0212863 A1)

Ishimaru is a strikingly parallel disclosure. It addresses the identical problem — modulation distortion caused by thermal-transient gain variation at the start of power amplification — and proposes the same class of solution:

• A "speedup circuit 122" that, "at a rise time of the control voltage of the control voltage source 135 (at turn-on of the amplifier)," transiently increases the bias fed to the amplifier transistor 103 through the bias power source section (bias circuit 111 + power source circuit 112), shortening the time to thermal equilibrium and reducing signal distortion. (¶¶ 12–22, 42–52.)
• The speedup circuit contains an RC network (capacitor 121, resistor 136) whose time constant shapes the transient, plus transistor 119, which the petitioner's expert characterized as a current amplifier that sinks/amplifies the RC-generated current and pulls a correction current out of the primary biasing circuit (node 117/output 118), raising the bias transistor 107's base drive and boosting I_BIAS to the amplifier.
• Ishimaru expressly ties the technique to dynamic EVM: adjusting the capacitance "so as to cancel transient variations of gain due to temperature variations at a start of the power amplification ... the value of dynamic EVM ... can be improved" (¶¶ 32–33).

Element-by-element mapping (claim 1, per the IPR petition): [1.0]/[1.1] amplifier transistor 103 amplifying RF input through matching networks — disclosed; [1.2] bias circuit 111/power-source circuit 112 + speedup circuit 122 — disclosed; [1.2.1] RC network (C121/R136) shapes the turn-on control signal into a time-varying current — disclosed (subject to the "enable signal" dispute, below); [1.2.2] transistor 119 amplifies that current — disclosed; [1.2.3] correction current at node 118 modulates the bias of transistor 107 and thus I_BIAS to amplifier transistor 103, correcting startup gain — disclosed; [1.2.4] "current amplifier including a current mirror" — disputed (see § 6).

Dependent limitations: claim 2/18 (RC network — expressly disclosed in Ishimaru); claim 20 (HBT gain compensation — Ishimaru's amplifier transistor 103 is a bipolar device used in an RF PA, and the transient collector-current behavior plotted in Ishimaru's Figure 3 is the HBT thermal-drift effect; a POSITA would recognize the applicability).

Why Ishimaru is the natural lead reference. It is a single, enabling, pre-2011 disclosure of nearly the entire claimed combination, solving the same problem with the same architecture. Under KSR, where a prior-art reference "addresses exactly the same problem" with "nearly identical" structure, the obviousness case is at its apex. Notably, Ishimaru is cited in the '101 continuation family's own record (US10566943B2's citation list includes US20090212863A1), confirming its status as recognized related art.

5. The disputed limitations and the secondary references

Two claim limitations drive every validity question, and each maps to a specific secondary reference or construction battle:

5.1 "Enable signal" (claims 1, 17, 21 and their dependents)

• Petitioner's position: Ishimaru's control voltage source 135 turning on is the PA enable event; the speedup circuit is triggered by the rise of that control voltage (the "rise time ... at turn-on of the amplifier").
• Patent Owner's position (adopted in Skyworks' ITC submissions): V135 is a power source/rail, not a state-changing enable signal; a power source's rise time is not an enable signal, and Ishimaru never describes gating the PA output on/off (pulsing) with this node.
• Technical read: This is the weakest Patent Owner argument as a pure technical matter — the circuit of Ishimaru Figure 1 plainly uses V135 to switch the bias network on and off, and a "power amplifier enable signal" in the '101 sense is functionally a control input that turns the bias/PA on. A POSITA would readily understand V135's rise as the enable transition. The argument has more force only if "enable signal" is construed narrowly to require a logic-style, pulsed, mode-switching control (as in WLAN burst operation). This is a claim-construction-dependent dispute, not a strong technical distinction.

5.2 "Current amplifier including a current mirror" (the reason for allowance)

• Prosecution history: The Examiner allowed the claims over Alon (a Skyworks GaAs PA-bias reference whose "single transistor 204" current amplifier the Examiner held was not a current mirror). The Examiner's reasons for allowance: prior art "fails to fairly teach or suggest the claimed circuit comprising ... 'the current amplifier including a current mirror' structurally and functionally interconnected with other limitations in the manner as cited in the claim."
• Skyworks' construction: "current mirror" requires at least two transistors with tied base/gate terminals (consistent with Fig. 5 of the '101 patent: transistors 85/86 and 87/88 form two cascaded two-transistor mirrors).
• Petitioner's Ground 1: Ishimaru's transistor 119, operating as a current source/sink pair with the rest of the circuit, functions as a current mirror under the plain meaning.
• Petitioner's Ground 2 (Ishimaru + Harrison): Even under Skyworks' two-transistor construction, Harrison's textbook (Fig. 4.18) teaches the canonical two-transistor NPN current mirror with tied bases, diode-connected input transistor, and gain set by emitter-area ratio — a circuit element that was a "staple" of analog design long before 2011.

6. Combination analysis

Ground A — Ishimaru alone (claims 1–2, 10–11, 17–18, 20–22)

Strength: High for everything except [1.2.4]. Ishimaru discloses the problem, the architecture, the RC shaping, the transient current boost, the bias-current correction, and the dynamic-EVM benefit. If "current mirror" is given its broad plain meaning (any circuit that mirrors/scales a current), Ishimaru's transistor 119 — which the petition shows receives the RC-generated current on one side and sinks a scaled version from the bias circuit on the other — plausibly reads on the limitation, and no combination is even needed.

Weakness: If "current mirror" requires two tied-base transistors (the construction consistent with the prosecution history and Fig. 5), Ishimaru's single-transistor 119 does not satisfy [1.2.4], and the entire obviousness case then turns on whether adding the second transistor is itself obvious. That is the crux of Ground B.

Ground B — Ishimaru in view of Harrison (claims 1–2, 10–11, 17–18, 20–22)

This is the strongest formal § 103 combination, and it is precisely the ground Kangxi presented. The technical logic:

1. Same-field, complementary references. Ishimaru is an RF-PA bias-circuit patent; Harrison is a standard analog-design reference teaching current-source/mirror building blocks used "in most analog IC designs." A POSITA designing PA bias circuits would know Harrison's basic mirror (or its equivalent in Gray & Meyer, Razavi, etc.) as a matter of routine professional knowledge. KSR's "known, predictable solution to a known problem" framework fits.

2. The combination is a simple substitution of a known sub-circuit for a functionally similar element. Ishimaru already needs an amplifier/sink (transistor 119) to scale the RC control current into the correction current. Replacing a single-transistor current amplifier with a standard two-transistor current mirror preserves the circuit's function while providing textbook benefits a POSITA would immediately recognize: (i) gain set by emitter-area ratio rather than by transistor β (β varies widely — e.g., 60–150 — with process/current, whereas area ratios are precisely controlled); (ii) better isolation between the timing/control side and the bias side; (iii) scalability to higher, more predictable mirror ratios; and (iv) temperature robustness — Harrison expressly notes the mirror equations hold over −60°C to +150°C, which matters in a PA that self-heats at turn-on.

3. Motivation independent of the '101 patent. The motivation is not hindsight: it is the standard reason any analog designer uses a current mirror — to get a well-defined, ratio-controlled current copy instead of an uncontrolled β-dependent copy. The '101 patent's own Fig. 5 implementation (two cascaded two-transistor mirrors, 85/86 and 87/88) is exactly the Harrison-style circuit inserted into the Ishimaru topology.

4. Reasonable expectation of success is high. The modification is a one-for-one block substitution in a DC-bias path, not a change to the RF signal path; both Ishimaru's and Harrison's circuits are bipolar, ground-referenced, and operate from the same V1 rail. Nothing in Ishimaru suggests the speedup circuit is optimized such that a mirror substitution would break it.

5. Claim 12/14-type detail (primary bias circuit / RC topology), if present in the challenged set, is disclosed by Ishimaru's bias power source circuit 112 (transistors 115/116/119, resistors, node 117 driving bias transistor 107) in combination with Harrison's mirror — the "two resistors + two BJTs + correction-current injection at an emitter node" structure of the '101 Fig. 5 primary bias circuit is a conventional Vbe-multiplier/reference arrangement that a POSITA would find trivially in the prior art.

Ground C — Ishimaru in view of Alon (and Alon-family art)

Alon (the Skyworks GaAs bias reference from prosecution) is a weaker lead reference than Ishimaru because it lacks the time-dependent startup-correction teaching — the very feature that makes Ishimaru so strong. But Alon is useful in the combination for a different purpose: it shows that a single-transistor or mirror-based current amplifier pulling correction current out of a primary bias circuit in a GaAs HBT PA was already known in Skyworks' own product art, defeating any argument that the combination of (bias circuit + correction-current injection) was novel or non-obvious. If anything, Alon + Ishimaru together make Ground B's substitution argument even more routine: both sides of the industry (Ishimaru/Sharp for the speedup function; Alon/Skyworks for mirror-style bias control in HBT PAs) had the pieces in place before the 2011 priority date.

7. The counterarguments (why the case is not slam-dunk)

An honest analysis must weigh the following, which the record shows persuaded the Examiner in 2013 and informed the PTAB's 2025 denial:

1. Ishimaru arguably teaches away from a controlled-gain mirror. The Director's institution decision noted that Ishimaru's solution "uses the uncontrolled level of amplification provided by the transistors in its speedup circuit" and that Ishimaru "explains that using an uncontrolled gain is one of the advantages of its approach." If Ishimaru affirmatively touts β-dependent (uncontrolled) gain as a benefit, then swapping in a ratio-controlled Harrison mirror contradicts the reference's design philosophy — the classic teaching-away that defeats obviousness.

2. Voltage-headroom concern. The Director's decision also noted petitioner's proposed modification "could cause insufficient voltage headroom for the proposed circuit to properly operate." In low-voltage battery PA bias circuits (VCC ~3.2–4.2 V, per the '101 patent's own Figs. 6–7), adding a second stacked diode-connected mirror transistor (VBE + VBE) can push the bias node out of compliance. If the combination would not work as proposed, the reasonable-expectation-of-success element fails.

3. "Enable signal" construction risk. If the district court/ITC construes "enable signal" to require a PA pulse/enable control distinct from a bias-rail power-on, Ishimaru's V135 (a "control voltage source") may not read on the limitation even in combination — Harrison adds nothing on this point (it is not a PA reference at all).

4. Prosecution-history estoppel / reason-for-allowance. The Examiner allowed the claims after the current-mirror amendment, expressly distinguishing Alon's single-transistor amplifier. Under Phillips, that history narrows "current mirror." Kangxi's Ground 2 was designed around this, but the PTAB found the motivation showing inadequate and the Petition was not instituted (denial was discretionary under Fintiv given the parallel ITC proceeding, with additional merits skepticism about Ground 2's motivation).

5. Secondary considerations. The '101 patent's own Figs. 7A/7B purport to show a dramatic dynamic-EVM improvement (roughly 3–5 dB in the plotted bands) attributable to the time-dependent-signal-generator + current-amplifier architecture — evidence of a non-obvious functional benefit, if the improvement is real and attributable to the claimed combination rather than to routine optimization.

6. No-infringement finding at the ITC. The January 2026 Initial Determination in 337-TA-1413 found no infringement of the '101 patent. Non-infringement is not invalidity, but it removed the commercial urgency from the validity question and the case settled/terminated in April 2026 — meaning no tribunal has ever reached a merits ruling invalidating any claim of the '101 patent.

8. Bottom line

• Ishimaru alone is a compelling obviousness case for every limitation except the "current mirror" element under the construction the patentee successfully obtained; on the broad plain meaning of "current mirror" it may knock out claims 1, 17, and 21 outright.
• Ishimaru + Harrison is the strongest formal combination: same problem, same architecture, plus a standard textbook mirror substitution with classic, well-documented motivations (ratio-set gain, isolation, temperature-stable mirroring). A POSITA would have been motivated to combine them with a high expectation of success — unless Ishimaru's stated preference for uncontrolled gain is read as a genuine teaching-away, and unless the added VBE stack creates a real headroom failure. Those two technical questions are the genuine battleground, and they are close calls that would likely require expert testimony on Ishimaru's Figure 1 operating points.
• Alon + Ishimaru reinforces that mirror-style correction-current injection into HBT PA bias circuits was industry-standard pre-2011, weakening any argument that the concept of the combination was novel.
• Practical reality: as of the current date (April 26, 2026), the '101 patent has survived every validity challenge actually pressed — the IPR was not instituted, and the ITC matter ended in a no-infringement finding and settlement, not a finding of invalidity. The claims' survival rests primarily on (a) the prosecution-history-narrowed "current mirror" construction, (b) Ishimaru's teaching-away/headroom defenses, and (c) the "enable signal" distinction. Each is a legitimate technical argument, but none is airtight; on a clean merits record with a broad "current mirror" construction, Ishimaru ± Harrison would present a substantial § 103 case against claims 1–2, 10–11, 17–18, and 20–22.

Verification pointers: IPR2025-00373 petition and Director's decision at https://ptacts.uspto.gov/ptacts/public-informations/petitions/1557168/...; Ishimaru full text at https://patents.google.com/patent/US20090212863A1/en; Harrison bibliographic record (ISBN 075067752X, Newnes 2005) at https://discover.libraryhub.jisc.ac.uk/ and http://web20.lib.cgu.edu.tw/webpac/detail/8335/; claim-element maps in the ITC respondent brief and Skyworks construction brief accessible via the ptacts artifact links above.

Final caveat: I was unable to retrieve the complete issued claim text of the '101 patent in this session, and the claim-numbering discrepancies noted above (claims 12/14 in earlier sections vs. claims 1–2/10–11/17–18/20–22 in the IPR record) could not be fully reconciled from snippets. If a filing depends on exact claim boundaries, pull the USPTO full-text PDF before relying on specific claim numbers in this analysis.