Patent US3980967A successfully refreshed from Google Patents.
US3980967A
Expired / Lapsed
US
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Differential feedback amplifier with frequency-shaped reference signal
Assignee: AT&T Inc
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Filing: 1975-03-14
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Granted: 1976-09-14
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Expires: 1995-03-14
Abstract
Abstract The reference signal applied to the differencing network of a differential feedback amplifier is shaped to conform to the natural gain-vs-frequency characteristic of the principal amplifier. This serves to minimize the amplitude of the error signal that the error amplifier must handle. As a result, the error amplifier is much smaller and can be optimized with respect to its noise and dispersion performance.
Inventors
- 👤 Harold Seidel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:38
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
79 words
A differential feedback amplifier comprising a principal amplifier having a given gain-vs-frequency characteristic which varies as a function of frequency; means for comparing a portion of the output signal derived from said principal amplifier with a reference signal and for forming a difference signal; means for amplifying and injecting said difference signal into the input end of said principal amplifier; characterized in that: the frequency characteristic of said reference signal follows essentially the gain-vs-frequency characteristic of said principal amplifier.
Claim 2
Dependent Claim
79 words
A differential feedback amplifier comprising a principal amplifier having a given gain-vs-frequency characteristic which varies as a function of frequency; means for comparing a portion of the output signal derived from said principal amplifier with a reference signal and for forming a difference signal; means for amplifying and injecting said difference signal into the input end of said principal amplifier; characterized in that: the frequency characteristic of said reference signal follows essentially the gain-vs-frequency characteristic of said principal amplifier.
Claim 3
Dependent Claim
18 words
The amplifier according to claim 1 including an equalizer connected to the output port of said differential amplifier.
Claim 4
Dependent Claim
27 words
The amplifier according to claim 2 wherein said equalizer has a compensating frequency characteristic for producing a flat gain characteristic over a specified frequency band of interest.
Claim 5
Dependent Claim
31 words
The amplifier according to claim 1 wherein the gain characteristic of said principal amplifier has a high frequency rolloff; and wherein said reference signal has the same high frequency rolloff characteristic.
Claim 6
Dependent Claim
173 words
A differential feedback amplifier comprising: a first differential amplifier having a gain characteristic which varies with frequency over a specified frequency band of interest; a second differential amplifier having a gain characteristic which is substantially constant over said specified frequency band of interest; a signal divider for coupling between a common input port and one of the input ports of each of said amplifiers; said divider having a coefficient of transmission t between said common input port and the one input port of said first amplifier, and a coefficient of coupling k between said common input port and the one input port of the second amplifier; a feedback path, including an attenuator, connecting the output port of said first amplifier to a second input port of said second amplifier; and means for coupling the output port of said second amplifier to a second input port of said first amplifier; characterized in that: the coupling coefficient k is proportional to the gain characteristic of said first amplifier over a specified frequency band of interest.
Claim 7
Dependent Claim
173 words
A differential feedback amplifier comprising: a first differential amplifier having a gain characteristic which varies with frequency over a specified frequency band of interest; a second differential amplifier having a gain characteristic which is substantially constant over said specified frequency band of interest; a signal divider for coupling between a common input port and one of the input ports of each of said amplifiers; said divider having a coefficient of transmission t between said common input port and the one input port of said first amplifier, and a coefficient of coupling k between said common input port and the one input port of the second amplifier; a feedback path, including an attenuator, connecting the output port of said first amplifier to a second input port of said second amplifier; and means for coupling the output port of said second amplifier to a second input port of said first amplifier; characterized in that: the coupling coefficient k is proportional to the gain characteristic of said first amplifier over a specified frequency band of interest.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-14 | 1980-03-15 | 1980-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-14 | 1984-03-15 | 1984-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-14 | 1988-03-15 | 1988-09-14 | $7700.00 | Window Closed / Lapsed |