US5286969A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for measuring optical power in an optical receiver with a non-linear element and a transconductance amplifier
Assignee: Nokia Bell Labs
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Filing: 1993-01-28
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Granted: 1994-02-15
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Expires: 2013-01-28
Abstract
Abstract An optical power monitoring circuit in an optical data receiver. A transconductance amplifier with non-linear feedback converts averaged photodiode current into a voltage representing a logarithm of the received optical power, which may be converted into decibels referenced to a standard power (dBm). The circuit has wide dynamic range and uses matched devices to provide processing and temperature compensation.
Inventors
- 👤 James G. Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:25
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H03F3/08; H03F3/087
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
79 words
An apparatus for monitoring the power of an optical signal received by a photodiode in an optical receiver, CHARACTERIZED BY: a first transconductance amplifier having an inverting input and an output; a first non-linear element, coupling between the inverting input and the output of the transconductance amplifier; wherein the photodiode couples to the inverting input of the amplifier and the output of the amplifier provides a voltage that is proportional to the logarithm of the received optical signal power.
Claim 2
Independent Claim
79 words
An apparatus for monitoring the power of an optical signal received by a photodiode in an optical receiver, CHARACTERIZED BY: a first transconductance amplifier having an inverting input and an output; a first non-linear element, coupling between the inverting input and the output of the transconductance amplifier; wherein the photodiode couples to the inverting input of the amplifier and the output of the amplifier provides a voltage that is proportional to the logarithm of the received optical signal power.
Claim 3
Dependent Claim
31 words
The apparatus as recited in claim 1, further characterized by a second non-linear element, coupling to the output of the amplifier, for proving compensation for variations in the first non-linear element.
Claim 4
Dependent Claim
14 words
The apparatus as recited in claim 2, wherein the non-linear elements are square-law devices.
Claim 5
Dependent Claim
14 words
The apparatus as recited in claim 3, wherein the photodiode is a PIN photodiode.
Claim 6
Dependent Claim
60 words
The apparatus as recited in claim 2, further characterized by: a second transconductance amplifier having an output and an input, the input coupling to the second non-linear element; a variable current source, coupling to the input of the second transconductance amplifier, for setting the output of the second amplifier to a desired level when a predetermined optical power is received.
Claim 7
Dependent Claim
26 words
The apparatus as recited in claim 5, wherein each of the square-law devices are darlington-connected bipolar transistor pairs with corresponding transistors of the pairs being matched.
Claim 8
Dependent Claim
33 words
The apparatus as recited in claim 1, further characterized by a circuit means, coupling to the inventing input of the first amplifier, for providing a current to compensate for leakage through the photodiode.
Claim 9
Dependent Claim
26 words
The apparatus as received in claim 7, wherein each of the square-law devices are darlington-connected bipolar transistor pairs with corresponding transistors of the pairs being matched.
Claim 10
Independent Claim
163 words
An apparatus for monitoring the power of an optical signal received by a photodiode in an optical receiver, CHARACTERIZED BY: a first transconductance amplifier having an inverting input and an output; a first square-law device, coupling between the inverting input and the output of the transconductance amplifier; a second square-law device, coupling to the output of the first amplifier, for providing compensation for variations in the first square-law device; a second transconductance amplifier having an output and an input, the input coupling in series with the second square-law device to the output of the first transconductance amplifier; a variable current source, coupling to the input of the second transconductance amplifier, for setting the output of the second transconductance amplifier to a desired level when a predetermined optical power is received; wherein the photodiode couples to the inverting input of the first amplifier and the output of the amplifier provides a voltage that is proportional to the logarithm of the received optical signal power.
Claim 11
Independent Claim
163 words
An apparatus for monitoring the power of an optical signal received by a photodiode in an optical receiver, CHARACTERIZED BY: a first transconductance amplifier having an inverting input and an output; a first square-law device, coupling between the inverting input and the output of the transconductance amplifier; a second square-law device, coupling to the output of the first amplifier, for providing compensation for variations in the first square-law device; a second transconductance amplifier having an output and an input, the input coupling in series with the second square-law device to the output of the first transconductance amplifier; a variable current source, coupling to the input of the second transconductance amplifier, for setting the output of the second transconductance amplifier to a desired level when a predetermined optical power is received; wherein the photodiode couples to the inverting input of the first amplifier and the output of the amplifier provides a voltage that is proportional to the logarithm of the received optical signal power.
Claim 12
Dependent Claim
33 words
The apparatus as received in claim 9, further characterized by a circuit means, coupling to the inverting input of the first amplifier, for providing a current to compensate for leakage through the photodiode.
Claim 13
Dependent Claim
26 words
The apparatus as received in claim 10, wherein each of the square-law devices are darlington-connected bipolar transistor pairs with corresponding transistors of the pairs are matched.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-02-14 | 1997-08-16 | 1998-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-14 | 2001-08-16 | 2002-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-14 | 2005-08-16 | 2006-02-15 | $7700.00 | Window Closed / Lapsed |