US4532477A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Distortion compensation for a microwave amplifier
Assignee: Nokia Bell Labs
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Filing: 1983-12-23
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Granted: 1985-07-30
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Expires: 2003-12-23
Abstract
Abstract Amplifier-produced distortion known as amplitude modulation to phase modulation (AM/PM) conversion is reduced through the use of GaAs FETs which are biased to generate AM/PM having an algebraic sign opposite to that generated by the amplifier. This algebraic sign reversal is accomplished by biasing the GaAs FETs so that a DC drain current ≦75% and ≧10% of the short-circuit drain current is established. In the disclosed embodiment, several GaAs FETs are cascaded in alternation with attenuators to increase the magnitude of the compensating AM/PM conversion without generating substantial amplitude modulation to amplitude modulation (AM/PM) conversion.
Inventors
- 👤 Donald R. Green, Jr.
- 👤 James P. Moffatt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:35
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/30; H03F1/306; H03F1/32; H03F1/3241; H03F3/00; H03F3/60; H03F3/601
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
86 words
Apparatus for use in a communication system wherein an amplifier generates distortion known as amplitude modulation to phase modulation conversion in an input signal, said apparatus comprising at least one GaAs field-effect transistor for receiving said signal, said transistor having gate, source and drain terminals; and means for biasing said terminals independently of said input signal so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 2
Dependent Claim
86 words
Apparatus for use in a communication system wherein an amplifier generates distortion known as amplitude modulation to phase modulation conversion in an input signal, said apparatus comprising at least one GaAs field-effect transistor for receiving said signal, said transistor having gate, source and drain terminals; and means for biasing said terminals independently of said input signal so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 3
Dependent Claim
32 words
The apparatus of claim 1 wherein each of said transistors has a short-circuit drain current and said biasing means establishes a DC drain current ≦75% and ≧10% of the short-circuit drain current.
Claim 4
Dependent Claim
18 words
The apparatus of claim 2 wherein said biasing means biases each of said transistors for class A operation.
Claim 5
Dependent Claim
8 words
The apparatus of claim 3 further including attenuators.
Claim 6
Dependent Claim
15 words
The apparatus of claim 4 wherein said attenuators are cascaded in alternation with said transistors.
Claim 7
Dependent Claim
36 words
The apparatus of claim 5 wherein each of said attenuators reduces the drive level of an immediately succeeding one of said transistors to minimize the generation of distortion known as amplitude modulation to amplitude modulation conversion.
Claim 8
Independent Claim
82 words
A method of reducing distortion known as amplitude modulation to phase modulation conversion which is generated in a signal by an amplifier, said method comprising the steps of coupling said signal to at least one GaAs field-effect transistor having gate, source, and drain terminals; and biasing said terminals independently of said signal so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 9
Independent Claim
82 words
A method of reducing distortion known as amplitude modulation to phase modulation conversion which is generated in a signal by an amplifier, said method comprising the steps of coupling said signal to at least one GaAs field-effect transistor having gate, source, and drain terminals; and biasing said terminals independently of said signal so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 10
Dependent Claim
32 words
The method of claim 7 wherein each of said transistors has a short-circuit drain current and said biasing means establishes a DC drain current ≦75% and ≧10% of the short-circuit drain current.
Claim 11
Dependent Claim
16 words
The method of claim 8 wherein each of said transistors is biased for class A operation.
Claim 12
Dependent Claim
15 words
The method of claim 9 further including the step of coupling said signal through attenuators.
Claim 13
Dependent Claim
15 words
The method of claim 10 wherein said attenuators are cascaded in alternation with said transistors.
Claim 14
Dependent Claim
36 words
The method of claim 11 wherein each of said attenuators reduces the drive level of an immediately succeeding one of said transistors to minimize the generation of distortion known as amplitude modulation to amplitude modulation conversion.
Claim 15
Dependent Claim
83 words
Apparatus for use in a communication system wherein an amplifier generates distortion known as amplitude modulation to phase modulation conversion in an input signal, said apparatus comprising at least one single gate GaAs field-effect transistor for receiving said signal, said transistor having gate, source and drain terminals; and means for biasing said terminals so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 16
Dependent Claim
83 words
Apparatus for use in a communication system wherein an amplifier generates distortion known as amplitude modulation to phase modulation conversion in an input signal, said apparatus comprising at least one single gate GaAs field-effect transistor for receiving said signal, said transistor having gate, source and drain terminals; and means for biasing said terminals so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 17
Independent Claim
80 words
A method of reducing distortion known as amplitude modulation to phase modulation conversion which is generated in a signal by an amplifier, said method comprising the steps of coupling said signal to at least one single gate GaAs field-effect transistor having gate, source and drain terminals; and biasing said terminals so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
Claim 18
Independent Claim
80 words
A method of reducing distortion known as amplitude modulation to phase modulation conversion which is generated in a signal by an amplifier, said method comprising the steps of coupling said signal to at least one single gate GaAs field-effect transistor having gate, source and drain terminals; and biasing said terminals so that said transistor generates amplitude modulation to phase modulation conversion in said signal, said conversion having an algebraic sign opposite to that generated in said signal by said amplifier.
References Cited (Backward Citations)
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