Patent US4139767A successfully refreshed from Google Patents.
US4139767A
Expired / Lapsed
US
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Photodetector with improved signal-to-noise ratio
Assignee: Nortel Networks Ltd
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Filing: 1977-10-17
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Granted: 1979-02-13
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Expires: 1997-10-17
Abstract
Abstract A novel photodetector circuit utilizing both the generated photovoltage, as well as its inverse, to improve the signal-to-noise ratio at the optical receiver output.
Inventors
- 👤 Tadeusz Witkowicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:52
CPC Classifications
H; H01; H01J; H01J40/00; H01J40/02; H01J40/14
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
89 words
A photodetector/receiver circuit comprising: a voltage source having a positive and a negative terminal; a first resistor connected between said positive terminal and the cathode of a photodetector diode; a second resistor substantially equal in resistance value to said first resistor, connected between said negative terminal and the anode of said photodetector diode; said anode and cathode capacitively coupled, one to the inverting input of a differential amplifier, and the other to the noninverting input; and the output of said differential amplifier comprising the output of said photodetector/receiver circuit.
Claim 2
Dependent Claim
89 words
A photodetector/receiver circuit comprising: a voltage source having a positive and a negative terminal; a first resistor connected between said positive terminal and the cathode of a photodetector diode; a second resistor substantially equal in resistance value to said first resistor, connected between said negative terminal and the anode of said photodetector diode; said anode and cathode capacitively coupled, one to the inverting input of a differential amplifier, and the other to the noninverting input; and the output of said differential amplifier comprising the output of said photodetector/receiver circuit.
Claim 3
Dependent Claim
25 words
The photodetector/receiver of claim 1, said photodetector diode being a PIN diode coupled to a fibre optic transmission cable to receive modulated light transmitted therethrough.
References Cited (Backward Citations)
US2616289A
Cited
US3430106A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-12 | 1982-08-14 | 1983-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-12 | 1986-08-14 | 1987-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-12 | 1990-08-14 | 1991-02-13 | $7700.00 | Window Closed / Lapsed |