US3873936A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for reducing distortion in a repeatered transmission system
Assignee: AT&T Inc
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Filing: 1974-03-07
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Granted: 1975-03-25
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Expires: 1994-03-07
Abstract
Abstract The distortion generated due to the nonlinear characteristics of the power amplifier in a repeater network is substantially reduced by generating a compensating signal in a feedforward amplifier network. In the feedforward network an auxiliary amplifier having substantially the same gain and distortion characteristics as the main power amplifier generates a compensating signal having a linear component equal to the linear component of the output signal of the power amplifier and a distortion component equal in magnitude to the distortion component of the output signal of the power amplifier. The phase relationship between the linear and distortion components at the output of the auxiliary amplifier is, however, opposite to the phase relationship between the linear and distortion components of the power amplifier. Thus, when the compensating signal is combined with the output of the power amplifier, the distortion components are substantially canceled and the linear components are added. The substantially distortion-free output signal has greater power than was obtainable in prior art feedforward distortion reduction networks.
Inventors
- 👤 Yo-Sung Cho
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:21
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/06; H03; H03F; H03F1/00; H03F1/32; H03F1/3223; H03F1/3229
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
426 words
In a repeatered transmission system having a plurality of repeater amplifiers connected in a transmission path between a transmitting and receiving station at least one of said repeater amplifiers comprising an input terminal for receiving an input signal, two signal paths, the first of said signal paths including in cascade a main amplifier and a first delay line, said main amplifier introducing signal distortion due to the nonlinearity of said main amplifier, the second of said signal paths including in cascade a second delay line and an auxiliary amplifier, said auxiliary amplifier having substantially the same gain and distortion characteristics as said main amplifier, first coupling means connecting said input terminal with said first signal path and said second signal path to couple a portion of said input signal to said first signal path and the remaining portion of said input signal to said second signal path, second coupling means connecting the outputs of said main amplifier and said second delay line with the inputs of said first delay line and said auxiliary amplifier to couple to the input of said auxiliary amplifier at least a portion of the output of said main amplifier and the output of said second delay line, the magnitude of the linear component of the input signal to said auxiliary amplifier being substantially equal to the magnitude of the linear component of the input signal to said main amplifier, the phase relationship between the linear and distortion components of the input signal to said auxiliary amplifier being opposite to the phase relationship between the linear and distortion components of the output signal of said main amplifier, the magnitudes of the linear and distortion components of the output signal of said auxiliary amplifier each being respectively equal to the magnitudes of the linear and distortion components of the output signal of the main amplifier, the phase relationship between the linear and distortion components of the output signal of said auxiliary amplifier being opposite to the phase relationship between the linear and distortion components of the output signal of said main amplifier, an output terminal, and combining means connecTing the output of said first delay line with the output of said auxiliary amplifier and said output terminal to combine the delayed linear and distortion components of the output signal of said main amplifier with the linear and distortion components of the output signal of said auxiliary amplifier such that the linear components are added and the distortion components are canceled whereby the output signal at said output terminal is substantially free from distortion.
Claim 2
Dependent Claim
426 words
In a repeatered transmission system having a plurality of repeater amplifiers connected in a transmission path between a transmitting and receiving station at least one of said repeater amplifiers comprising an input terminal for receiving an input signal, two signal paths, the first of said signal paths including in cascade a main amplifier and a first delay line, said main amplifier introducing signal distortion due to the nonlinearity of said main amplifier, the second of said signal paths including in cascade a second delay line and an auxiliary amplifier, said auxiliary amplifier having substantially the same gain and distortion characteristics as said main amplifier, first coupling means connecting said input terminal with said first signal path and said second signal path to couple a portion of said input signal to said first signal path and the remaining portion of said input signal to said second signal path, second coupling means connecting the outputs of said main amplifier and said second delay line with the inputs of said first delay line and said auxiliary amplifier to couple to the input of said auxiliary amplifier at least a portion of the output of said main amplifier and the output of said second delay line, the magnitude of the linear component of the input signal to said auxiliary amplifier being substantially equal to the magnitude of the linear component of the input signal to said main amplifier, the phase relationship between the linear and distortion components of the input signal to said auxiliary amplifier being opposite to the phase relationship between the linear and distortion components of the output signal of said main amplifier, the magnitudes of the linear and distortion components of the output signal of said auxiliary amplifier each being respectively equal to the magnitudes of the linear and distortion components of the output signal of the main amplifier, the phase relationship between the linear and distortion components of the output signal of said auxiliary amplifier being opposite to the phase relationship between the linear and distortion components of the output signal of said main amplifier, an output terminal, and combining means connecTing the output of said first delay line with the output of said auxiliary amplifier and said output terminal to combine the delayed linear and distortion components of the output signal of said main amplifier with the linear and distortion components of the output signal of said auxiliary amplifier such that the linear components are added and the distortion components are canceled whereby the output signal at said output terminal is substantially free from distortion.
Claim 3
Dependent Claim
51 words
A repeater amplifier for a transmission system as defined in claim 1 further including signal multiplying means connected between the output of said second coupling means in said second signal path and the input of said auxiliary amplifier to multiply the output of said second coupling means by a predetermined factor.
Claim 4
Dependent Claim
91 words
A repeater amplifier for a repeatered transmission system as defined in claim 2 wherein the magnitude of the portion of said input signal coupled to said second signal path is m times the magnitude of the input signal coupled to the first signal path, said main and auxiliary amplifiers have a gain factor of A, said second coupling means couples 2m/3A times the output of said main amplifier to said second signal path, and said signal multiplying means has a gain factor of 3/m, where m is a non-zero positive value.
Claim 5
Dependent Claim
231 words
A feed-forward amplifier configuration for providing a substantially distortion-free amplification of an input signal comprising first and second amplifier means having substantially identical amplification and distortion characteristics, a first and second delay network means each having an input terminal and an output terminal, an input coupler means for coupling to an input of said first amplifier means a portion of said input signal and for coupling the remaining portion of said input signal to the input terminal of said first delay network, a fourport interstage coupling means for coupling a signal at the output of said first amplifier means substantially unaltered to the input terminal of said second delay network means and for coupling both a portion of the output signal from said first amplifier means and the signal at the output terminal of said first delay network means to the input of said second amplifier means, output coupling means for developing an output signal by combining signals at the output terminal of said second delay network means with the output of said second amplifier means, the phase characteristics of said input coupling means and said interstage coupling means being arranged such that the phase relationship between the amplified linear and distortion components at the output of said second amplifier means is opposite the phase relationship between the amplified linear and distortion components at the output of said first amplifier means.
Claim 6
Dependent Claim
231 words
A feed-forward amplifier configuration for providing a substantially distortion-free amplification of an input signal comprising first and second amplifier means having substantially identical amplification and distortion characteristics, a first and second delay network means each having an input terminal and an output terminal, an input coupler means for coupling to an input of said first amplifier means a portion of said input signal and for coupling the remaining portion of said input signal to the input terminal of said first delay network, a fourport interstage coupling means for coupling a signal at the output of said first amplifier means substantially unaltered to the input terminal of said second delay network means and for coupling both a portion of the output signal from said first amplifier means and the signal at the output terminal of said first delay network means to the input of said second amplifier means, output coupling means for developing an output signal by combining signals at the output terminal of said second delay network means with the output of said second amplifier means, the phase characteristics of said input coupling means and said interstage coupling means being arranged such that the phase relationship between the amplified linear and distortion components at the output of said second amplifier means is opposite the phase relationship between the amplified linear and distortion components at the output of said first amplifier means.
Claim 7
Dependent Claim
22 words
A feed-forward amplifier configuration as defined in claim 4 wherein said input, interstage and output coupling means each include a hybrid transformer.
Claim 8
Dependent Claim
337 words
A feed-forward amplifier configuration comprising an input terminal for receiving an input signal, a first power amplifier which produces linear and distortion components at its output in response to a signal at its input due to its nonlinearity, a first and second delay network means each having an input terminal and an output terminal, an input coupler means for coupling to the input of said first power amplifier a portion of said input signal and for coupling the remaining portion of said input signal to the input terminal of said first delay network means, a four-port interstage coupler having first and second input terminals and first and second output terminals with substantially no attenuation between said first input terminal and said first output terminal, means for coupling the output of said first power amplifier to the first input terminal of said interstage coupler, means for connecting the output terminal of said first delay network means to the second input terminal of said interstage Coupler, means for connecting the first output terminal of said interstage coupler to the input terminal of said second delay network, and an output coupler means having first and second input terminals with its first input terminal connected to the output terminal of said second delay-means for developing an output signal by combining the signal at the output terminal of said second delay network means with a signal presented at the second input terminal of the output coupler means, characterized in that said input coupler means and said interstage coupler are designed to couple to the second output terminal of said interstage coupler a signal having linear and distortion components with a phase relationship to each other opposite to the phase relationship between the linear and distortion components at the output of said first main amplifier, and the second output terminal of said interstage coupler is coupled to the second input terminal of said output coupler means by a second power amplifier having amplification and distortion characteristics substantially identical to said first power amplifier.
Claim 9
Dependent Claim
337 words
A feed-forward amplifier configuration comprising an input terminal for receiving an input signal, a first power amplifier which produces linear and distortion components at its output in response to a signal at its input due to its nonlinearity, a first and second delay network means each having an input terminal and an output terminal, an input coupler means for coupling to the input of said first power amplifier a portion of said input signal and for coupling the remaining portion of said input signal to the input terminal of said first delay network means, a four-port interstage coupler having first and second input terminals and first and second output terminals with substantially no attenuation between said first input terminal and said first output terminal, means for coupling the output of said first power amplifier to the first input terminal of said interstage coupler, means for connecting the output terminal of said first delay network means to the second input terminal of said interstage Coupler, means for connecting the first output terminal of said interstage coupler to the input terminal of said second delay network, and an output coupler means having first and second input terminals with its first input terminal connected to the output terminal of said second delay-means for developing an output signal by combining the signal at the output terminal of said second delay network means with a signal presented at the second input terminal of the output coupler means, characterized in that said input coupler means and said interstage coupler are designed to couple to the second output terminal of said interstage coupler a signal having linear and distortion components with a phase relationship to each other opposite to the phase relationship between the linear and distortion components at the output of said first main amplifier, and the second output terminal of said interstage coupler is coupled to the second input terminal of said output coupler means by a second power amplifier having amplification and distortion characteristics substantially identical to said first power amplifier.
References Cited (Backward Citations)
US3725806A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |