Patent US4774477A successfully refreshed from Google Patents.
US4774477A
Expired / Lapsed
US
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Power amplifier having low intermodulation distortion
Assignee: Boeing North American Inc
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Filing: 1987-03-18
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Granted: 1988-09-27
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Expires: 2007-03-18
Abstract
Abstract Intermodulation distortion in RF FET amplifiers operating in the Class AB mode is reduced without limiting the bandwidth by providing transformer coupled outputs from both the source and drain circuits. The negative feedback provided by the transformer in the source circuit reduces distortion but does not limit bandwidth in the manner of the reactive network normally used for correct phasing in circuits employing drain to gate feedback. Using this technique, the distortion components are typically 40-45 dB below the desired signal when a two-tone test is used, which exceeds the typically available level of 30 dB in prior art circuits.
Inventors
- 👤 William D. Rodes
- 👤 David L. Krett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:07
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/32; H03F1/3223
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
124 words
A power amplifier exhibiting low intermodulation distortion and wideband performance, comprising: input circuit means for receiving an RF signal to be amplified; a field-effect-transistor having a gate terminal, a source terminal, and a drain terminal, said gate terminal being coupled to the input circuit means for receipt of the signal to be amplified, said transistor further being biased for class AB amplification of said signal; a first transformer the primary winding of which is coupled to the drain terminal of said transistor to receive said amplified signal; a second transformer the primary winding of which is coupled to the source terminal of said transistor to receive said amplified signal; and circuit means for combining the amplified signal passing through the first and second transformers.
Claim 2
Dependent Claim
124 words
A power amplifier exhibiting low intermodulation distortion and wideband performance, comprising: input circuit means for receiving an RF signal to be amplified; a field-effect-transistor having a gate terminal, a source terminal, and a drain terminal, said gate terminal being coupled to the input circuit means for receipt of the signal to be amplified, said transistor further being biased for class AB amplification of said signal; a first transformer the primary winding of which is coupled to the drain terminal of said transistor to receive said amplified signal; a second transformer the primary winding of which is coupled to the source terminal of said transistor to receive said amplified signal; and circuit means for combining the amplified signal passing through the first and second transformers.
Claim 3
Dependent Claim
163 words
A power amplifier exhibiting low intermodulation distortion and wideband performance comprising: means for receiving an RF signal; means for dividing the RF signal into two components; first input circuit means for receiving a first component of said RF signal; a first field-effect-transistor having source, drain, and gate terminals, said gate terminal coupled to the first input circuit means; a second input circuit means for receiving a second component of said RF signal; a second field-effect-transistor having source, drain, and gate terminals, said gate terminal coupled to the second input circuit means; first output circuit means coupled to the drain terminals of both the first and second field-effect-transistors for receiving a first portion of the amplified signal; second output circuit means coupled to the source terminals of both the first and second field-effect-transistors for receiving a second portion of the amplified signal; and means coupled to the first and second output circuit means for combining said first and second portions of said amplified signal.
Claim 4
Dependent Claim
163 words
A power amplifier exhibiting low intermodulation distortion and wideband performance comprising: means for receiving an RF signal; means for dividing the RF signal into two components; first input circuit means for receiving a first component of said RF signal; a first field-effect-transistor having source, drain, and gate terminals, said gate terminal coupled to the first input circuit means; a second input circuit means for receiving a second component of said RF signal; a second field-effect-transistor having source, drain, and gate terminals, said gate terminal coupled to the second input circuit means; first output circuit means coupled to the drain terminals of both the first and second field-effect-transistors for receiving a first portion of the amplified signal; second output circuit means coupled to the source terminals of both the first and second field-effect-transistors for receiving a second portion of the amplified signal; and means coupled to the first and second output circuit means for combining said first and second portions of said amplified signal.
Claim 5
Dependent Claim
18 words
A power amplifier circuit as described in claim 2 wherein said first output circuit means includes a transformer.
Claim 6
Dependent Claim
18 words
A power amplifier circuit as described in claim 3 wherein said second output circuit means includes a transformer.
Claim 7
Dependent Claim
21 words
A power amplifier circuit as described in claim 4 wherein said first and second field-effect-transistors are biased for Class AB operation.
Claim 8
Dependent Claim
95 words
An RF amplifier comprising: an input circuit for receiving an RF signal to be amplified; a FET having a source, a drain, and a gate, the gate and source of which form a portion of the input circuit; and an output circuit for receiving said signal from the FET, said output circuit incorporating the source and drain of said FET therein, said output circuit including a first transformer in series with said drain of said FET and a second transformer in series with said source of FET, to provide RF feedback to said input circuit.
Claim 9
Dependent Claim
95 words
An RF amplifier comprising: an input circuit for receiving an RF signal to be amplified; a FET having a source, a drain, and a gate, the gate and source of which form a portion of the input circuit; and an output circuit for receiving said signal from the FET, said output circuit incorporating the source and drain of said FET therein, said output circuit including a first transformer in series with said drain of said FET and a second transformer in series with said source of FET, to provide RF feedback to said input circuit.
Claim 10
Dependent Claim
20 words
An RF amplifier as described in claim 6 further including a signal combiner coupled to said first and second transformers.
Claim 11
Dependent Claim
17 words
An RF amplifier as described in claim 7 wherein said FET is biased for Class AB operation.
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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) | 1991-09-27 | 1992-03-28 | 1992-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-27 | 1996-03-28 | 1996-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-27 | 2000-03-28 | 2000-09-27 | $7700.00 | Window Closed / Lapsed |