US3463928A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency-selective negative feedback arrangement for phototransistor for attenuating unwanted signals
Assignee: Fairchild Semiconductor Corp
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Filing: 1966-11-03
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Granted: 1969-08-26
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Expires: 1986-11-03
Abstract
No abstract record available.
Inventors
- 👤 Howard E Murphy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:27
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H03F3/08
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
155 words
A PHOTODETECTOR CIRCUIT FOR DETECTING INTENSITY MODULATED LIGHT SIGNALS HAVING A PREDETERMINED BAND OF MODULATION FREQUENCIES COMPRISING: A PHOTOTRANSISTOR HAVING ITS EMITTER AND COLLECTOR CONNECTED IN SERIES WITH A LOAD TRANSISTOR BETWEEN A SUPPLY VOLTAGE INPUT TERMINAL AND A POINT OF REFERENCE POTENTIAL, SAID LOAD TRANSISTOR BEING OF A CONDUCTIVITY TYPE OPPOSITE TO THAT OF SAID PHOTOTRANSISTOR AND HAVING ITS COLLECTOR CONNECTED TO THE COLLECTOR OF SAID PHOTOTRANSISTOR AND ITS EMITTER CONNECTED TO A SUPPLY VOLTAGE TERMINAL, SAID LOAD TRANSISTOR BEING BIASED FOR CONSTANT COLLECTOR CURRENT; A NEGATIVE FEEDBACK PATH CONNECTED BETWEEN THE COLLECTOR AND THE BASE OF SAID PHOTOTRANSISTOR, SAID FEEDBACK PATH INCLUDING AN AMPLIFIER CONNECTED TO SERIES WITH A FILTER CIRCUIT WHICH PASSES D.C. SIGNALS AND ONLY THOSE A.C. SIGNALS HAVING FREQUENCIES OUTSIDE OF SAID PREDETERMINED FREQUENCY BAND; AND AN OUTPUT TERMINAL FOR SAID CIRCUIT CONNECTED TO SAID FEEDBACK PATH BETWEEN THE OUTPUT OF SAID PHOTOTRANSISTOR AND THE COLLECTOR OF SAID FILTER CIRCUIT.
Claim 2
Dependent Claim
155 words
A PHOTODETECTOR CIRCUIT FOR DETECTING INTENSITY MODULATED LIGHT SIGNALS HAVING A PREDETERMINED BAND OF MODULATION FREQUENCIES COMPRISING: A PHOTOTRANSISTOR HAVING ITS EMITTER AND COLLECTOR CONNECTED IN SERIES WITH A LOAD TRANSISTOR BETWEEN A SUPPLY VOLTAGE INPUT TERMINAL AND A POINT OF REFERENCE POTENTIAL, SAID LOAD TRANSISTOR BEING OF A CONDUCTIVITY TYPE OPPOSITE TO THAT OF SAID PHOTOTRANSISTOR AND HAVING ITS COLLECTOR CONNECTED TO THE COLLECTOR OF SAID PHOTOTRANSISTOR AND ITS EMITTER CONNECTED TO A SUPPLY VOLTAGE TERMINAL, SAID LOAD TRANSISTOR BEING BIASED FOR CONSTANT COLLECTOR CURRENT; A NEGATIVE FEEDBACK PATH CONNECTED BETWEEN THE COLLECTOR AND THE BASE OF SAID PHOTOTRANSISTOR, SAID FEEDBACK PATH INCLUDING AN AMPLIFIER CONNECTED TO SERIES WITH A FILTER CIRCUIT WHICH PASSES D.C. SIGNALS AND ONLY THOSE A.C. SIGNALS HAVING FREQUENCIES OUTSIDE OF SAID PREDETERMINED FREQUENCY BAND; AND AN OUTPUT TERMINAL FOR SAID CIRCUIT CONNECTED TO SAID FEEDBACK PATH BETWEEN THE OUTPUT OF SAID PHOTOTRANSISTOR AND THE COLLECTOR OF SAID FILTER CIRCUIT.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-08-25 | 1973-02-24 | 1973-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-08-25 | 1977-02-24 | 1977-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-08-25 | 1981-02-24 | 1981-08-26 | $7700.00 | Window Closed / Lapsed |