Invalidity dossier
US 5867015
Low drop-out voltage regulator with PMOS pass element
Current assignee: Texas Instruments Inc
Added 9/23/2026, 11:02:30 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 5,867,015 A
Title: Low Drop-Out Voltage Regulator with PMOS Pass Element
Assignee: Texas Instruments Incorporated (original and current assignee listed). Inventors: Marco Corsi, Robert B. Borden, Michael R. Kay, Nicolas Salamina, Gabriel A. Rincon.
Key dates: Provisional priority Dec. 19, 1996 (Ser. No. 60/033,679); application filed Dec. 17, 1997 (US 08/992,706); granted Feb. 2, 1999. Status: expired (anticipated expiration Dec. 17, 2017).
Purpose: A voltage regulator converts a varying input supply into a stable output voltage. In battery-powered systems, efficiency depends on the "drop-out" voltage (input-to-output difference while regulation is maintained) and on quiescent current — wasted current that shortens battery life. This invention seeks compensation of an LDO regulator while consuming only small currents, and substantially improved load regulation.
Plain-language scope (per the summary and description): The circuit comprises a first MOS transistor (PMOS pass device 12) between the supply line and an output node; a source follower (transistor 24) coupled to the pass device's gate; an amplifier (error amplifier 38) coupled to the source follower's gate; negative feedback circuitry between output node and amplifier; a current conveyor (46, formed by PNP transistors 16, 18 and NMOS transistors 20, 22) coupled to the pass device; and positive feedback circuitry (26, including transistor 28, capacitor 30, resistor 32) between the current conveyor and the source follower. A current mirror (transistor 14, e.g., 1:1000 ratio) monitors pass-device current; the conveyor equalizes V_DS and V_GS of the mirrored devices. Positive feedback modulates the source follower's V_GS proportionately with the pass device's V_GS to compensate output impedance, while resistor 32 and capacitor 30 ensure positive feedback never overcomes negative feedback (no oscillation). A ~1 µA current source 34 supports no-load operation, and transistor 36 enhances slew rate.
Source: https://patents.google.com/patent/US5867015/en
What the excerpt does not establish: The literal claim text is not reproduced (hence no claim-by-claim scope); details of the omitted description; and any legal conclusions as to validity, enforceability, or claim coverage.
Generated 10/1/2026, 9:32:58 PM
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PTAB challenges
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Assignment history
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Prior art
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