US3886470A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Feed-forward amplifier system
Assignee: Amplifier Design and Service Inc
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Filing: 1973-12-04
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Granted: 1975-05-27
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Expires: 1993-12-04
Abstract
Abstract A feed-forward amplifier system for producing a high output with low distortion and noise across a wide frequency band. An amplified signal is compared with a time-delayed unamplified signal in a sampling loop to isolate the noise and distortion components produced by the main amplifier. These noise and distortion components are then amplified by an auxiliary amplifier and combined with the amplified main signal to effectively cancel the error thereof. The output impedance of the main amplifier is completely mismatched with respect to the other components of the system and signals incident upon the output, although reflected off the main signal amplifier, do not reappear at the output because of the cancellation characteristic of the correction loop.
Inventors
- 👤 William A O'neil
- 👤 George H Ray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:12
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/32; H03F1/3223; H03F1/3229
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
314 words
A feed-forward amplifier system comprising: means for applying an input information signal to said amplifier; a first directional coupler for splitting the input signal; a main component amplifier for amplifyiNg a portion of the input signal from said directional coupler; a second directional coupler at the output of said main component amplifier for splitting the amplified information signal; a third directional coupler for combining the unamplified portion of the input information signal sampled by said first directional coupler and the small portion of the amplified signal from the main component amplifier and said second directional coupler; an auxiliary component amplifier for amplifying the combined signal from said third directional coupler; a fourth directional coupler for combining the output from said auxiliary component amplifier and the main portion of the amplified signal from said second directional coupler; first delay means for delaying the unamplified input information signal between said first and third directional couplers by a predetermined time equal to the delay in the main component amplifier signal path; and an output terminal coupled to said fourth directional coupler; said main component amplifier and siad first delay means being part of a sampling loop of said amplifier system; said auxiliary amplifier being part of a correction loop of said amplifier system; whereby noise and distortion errors injected by said main component amplifier are cancelled by means of the correction loop through said auxiliary amplifier when the auxiliary amplified signal is combined with the main signal at said fourth coupler; and wherein the output impedance of said main component amplifier is mismatched with respect to the other elements in said feedforward amplifier system so that signals injected at said output terminal are reflected by said main component amplifier and cancelled by means of said correction loop, thereby matching the output of said feed-forward amplifier system to a transmission line to which said output terminal is connected.
Claim 2
Dependent Claim
314 words
A feed-forward amplifier system comprising: means for applying an input information signal to said amplifier; a first directional coupler for splitting the input signal; a main component amplifier for amplifyiNg a portion of the input signal from said directional coupler; a second directional coupler at the output of said main component amplifier for splitting the amplified information signal; a third directional coupler for combining the unamplified portion of the input information signal sampled by said first directional coupler and the small portion of the amplified signal from the main component amplifier and said second directional coupler; an auxiliary component amplifier for amplifying the combined signal from said third directional coupler; a fourth directional coupler for combining the output from said auxiliary component amplifier and the main portion of the amplified signal from said second directional coupler; first delay means for delaying the unamplified input information signal between said first and third directional couplers by a predetermined time equal to the delay in the main component amplifier signal path; and an output terminal coupled to said fourth directional coupler; said main component amplifier and siad first delay means being part of a sampling loop of said amplifier system; said auxiliary amplifier being part of a correction loop of said amplifier system; whereby noise and distortion errors injected by said main component amplifier are cancelled by means of the correction loop through said auxiliary amplifier when the auxiliary amplified signal is combined with the main signal at said fourth coupler; and wherein the output impedance of said main component amplifier is mismatched with respect to the other elements in said feedforward amplifier system so that signals injected at said output terminal are reflected by said main component amplifier and cancelled by means of said correction loop, thereby matching the output of said feed-forward amplifier system to a transmission line to which said output terminal is connected.
Claim 3
Dependent Claim
65 words
The feed-forward amplifier system recited in claim 1 wherein said first delay means further includes phase correcting means comprising: a variable capacitor in shunt between said first directional coupler and said first coaxial cable coil; a shunt coil between said first coaxial cable coil and said third directional coupler; and a series capacitor also between said first coaxial cable coil and said third directional coupler.
Claim 4
Dependent Claim
63 words
The feed-forward amplifier system recited in claim 1 and further comprising second delay means for delaying the main portion of the amplified signal between said second and fourth directional couplers by a predetermined time equal to the delay in the error signal in the auxiliary component amplifier signal path, said second delay means including a second rigid coil of solid sheath coaxial cable.
Claim 5
Dependent Claim
65 words
The feed-forward amplifier system recited in claim 3 wherein said second delay means further includes phase correcting means comprising: a variable capacitor in shunt between said second directional coupler and said second coaxial cable coil; a shunt coil between said second coaxial cable coil and said fourth directional coupler; and a series capacitor also between said second coaxial cable coil and said fourth directional coupler.
Claim 6
Dependent Claim
72 words
The feed-forward amplifier system recited in claim 1 wherein said main component amplifier comprises: an integrated circuit amplifier; a first grounded base transistor connected between said integrated circuit amplifier and said second directional coupler thereby making the effective output impedance of said main component amplifier represent substantially an open circuit, the output impedance of said main component amplifier thereby being mismatched with respect to the other elements of said feed-forward amplifier system.
Claim 7
Dependent Claim
27 words
The feed-forward amplifier system recited in claim 5 wherein said main component amplifier further comprises; a second grounded base transistor connected in parallel with said first transistor.
Claim 8
Dependent Claim
31 words
The feed-forward amplifier system recited In claim 6 wherein said main component signal amplifier further comprises a variable gain control connected between said first directional coupler and said integrated circuit amplifier.
Claim 9
Dependent Claim
36 words
The feed-forward amplifier system recited in claim 7 wherein said auxiliary component amplifier comprises: an auxiliary integrated circuit amplifier; and a variable gain control connected between said third directional coupler and said auxiliary integrated circuit amplifier.
Claim 10
Dependent Claim
90 words
The feed-forward amplifier system recited in claim 1 wherein said main component amplifier comprises: an integrated circuit amplifier; a signal splitter connected to the output of said integrated circuit amplifier; a first center tapped transformer connected to one output port of said signal splitter; a second center tapped transformer connected to the other output port of said signal splitter; first and second grounded base transistors connected to the center taps of said first and second transformers respectively; and a signal combiner connected between said transistors and said second directional coupler.
Claim 11
Dependent Claim
236 words
A feed-forward amplifier system comprising: means for applying an input information signal to said amplifier; a first directional coupler for splitting the input signal; a main component amplifier for amplifying a portion of the input signal from said directional coupler; a second directional coupler at the output of said main component amplifier for unequally splitting the amplified information signal; a third directional coupler for combining the unamplified portion of the input information signal sampled by said first directional coupler and the small portion of the amplified signal from the main component amplifier and said second directional coupler; an auxiliary component amplifier for amplifying the combined signal from said third directional coupler; a fourth directional coupler for combining the output from said auxiliary component amplifier and the main portion of the amplified signal from said second directional coupler; and an output terminal coupled to said fourth directional coupler; said main component amplifier being part of a sampling loop of said amplifier system; said auxiliary amplifier being part of a correction loop of said amplifier system; said main component amplifier comprises: an integrated circuit amplifier; a first grounded base transistor connected between said integrated circuit and said second directional coupler thereby making the effective output impedance of said main component amplifier represent substantially an open circuit, the output impedance of said main component amplifier thereby being mismatched with respect to the other elements of said feed-forward amplifier system.
Claim 12
Dependent Claim
236 words
A feed-forward amplifier system comprising: means for applying an input information signal to said amplifier; a first directional coupler for splitting the input signal; a main component amplifier for amplifying a portion of the input signal from said directional coupler; a second directional coupler at the output of said main component amplifier for unequally splitting the amplified information signal; a third directional coupler for combining the unamplified portion of the input information signal sampled by said first directional coupler and the small portion of the amplified signal from the main component amplifier and said second directional coupler; an auxiliary component amplifier for amplifying the combined signal from said third directional coupler; a fourth directional coupler for combining the output from said auxiliary component amplifier and the main portion of the amplified signal from said second directional coupler; and an output terminal coupled to said fourth directional coupler; said main component amplifier being part of a sampling loop of said amplifier system; said auxiliary amplifier being part of a correction loop of said amplifier system; said main component amplifier comprises: an integrated circuit amplifier; a first grounded base transistor connected between said integrated circuit and said second directional coupler thereby making the effective output impedance of said main component amplifier represent substantially an open circuit, the output impedance of said main component amplifier thereby being mismatched with respect to the other elements of said feed-forward amplifier system.
Claim 13
Dependent Claim
27 words
A feed-forward amplifier system recited in claim 10 wherein said main component amplifier further comprises: a second grounded base transistor connected in parallel with said first transistor.
Claim 14
Dependent Claim
81 words
A feed-forward amplifier system recited in claim 11 wherein said main component amplifier further comprises: a signal splitter connected to the output of said integrated circuit amplifier; a first center tapped transformer connected to one output port of said signal splitter; a second center tapped transformer connected to the other output port of said signal splitter, said transistors being connected to the respective center taps of said transformers; and a signal combiner connected between said transistors and said second directional coupler.
Claim 15
Dependent Claim
109 words
The feed-forward amplifier system recited in claim 12 and further comprising: first delay means for delaying the unamplified input information signal between said first and third directional couplers by a predetermined time equal to the delay in the main component amplifier signal path, said first delay means including a first rigid coil of solid sheath coaxial cable; and second delay means for delaying the mAin portion of the amplified signal between said second and fourth directional couplers by a predetermined time equal to the delay in the error signal in the auxiliary amplifier signal path, said second delay means including a second rigid coil of solid sheath coaxial cable.
Claim 16
Dependent Claim
67 words
The feed-forward amplifier system recited in claim 13 wherein said first and second delay means further include phase correcting means comprising: a variable capacitor connected in shunt to the input of each of said coaxial cable coils; a shunt coil connected at the output of each of said coaxial cable coils; and a series capacitor also connected at the output of each of said coaxial cable coils.
Claim 17
Dependent Claim
38 words
The feed-forward amplifier system recited in claim 14 and further comprising a pi resistance pad connected between said second and third directional couplers to provide for coarse signal strength adjustment of the signals entering said third directional coupler.
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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |