US5442322A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power amplifier bias control circuit and method
Assignee: Alps Alpine Co Ltd
•
Filing: 1994-09-30
•
Granted: 1995-08-15
•
Expires: 2014-09-30
Abstract
Abstract A control circuit for a multi-stage power amplifier (such as in a portable radio transmitter) compensates for fluctuations in ambient temperature, load, signal level and power supply voltage, The control voltage is set by comparing a biasing level which is related to the amplifier input signal level to a voltage proportional to the power supply current of the last stage of the amplifier. The control voltage resulting from the comparison establishes the operating point of the last stage of the power amplifier.
Inventors
- 👤 Richard K. Kornfeld
- 👤 Ana L. Weiland
- 👤 Mitsunari Okazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:35
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/30; H03F1/306; H03F1/02; H03F1/0205; H03F1/0261
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
118 words
A power amplifier comprising: an FET amplifier stage having a power supply terminal and having an input terminal for receiving an externally provided variable amplitude signal and receiving a control signal at a control terminal; a current detector connected to said power supply terminal thereby detecting a power supply current provided to said power supply terminal of said FET amplifier stage, said current detector supplying a signal at an output terminal proportional to said power supply current; and a comparator having a first input terminal connected to a source of a reference signal and a second input terminal connected to the output terminal of said current detector, and providing in response said control signal to said amplifier stage.
Claim 2
Dependent Claim
118 words
A power amplifier comprising: an FET amplifier stage having a power supply terminal and having an input terminal for receiving an externally provided variable amplitude signal and receiving a control signal at a control terminal; a current detector connected to said power supply terminal thereby detecting a power supply current provided to said power supply terminal of said FET amplifier stage, said current detector supplying a signal at an output terminal proportional to said power supply current; and a comparator having a first input terminal connected to a source of a reference signal and a second input terminal connected to the output terminal of said current detector, and providing in response said control signal to said amplifier stage.
Claim 3
Dependent Claim
18 words
The amplifier of claim 1, wherein said control signal sets an operating point of said FET amplifier stage.
Claim 4
Dependent Claim
20 words
The amplifier of claim 1, wherein said power supply terminal is also a drain terminal of said FET amplifier stage.
Claim 5
Dependent Claim
23 words
The amplifier of claim 1, wherein said current detector comprises a first resistance connected between said power supply terminal and a power source.
Claim 6
Dependent Claim
40 words
The amplifier of claim 4, wherein said current detector further comprises an operational amplifier having a first input terminal connected to a first end of said resistance and a second input terminal connected to a second end of said resistance.
Claim 7
Dependent Claim
12 words
The amplifier of claim 1, wherein said comparator comprises an operational amplifier.
Claim 8
Dependent Claim
29 words
The amplifier of claim 1, further comprising at least one additional amplifier stage for providing said externally provided variable amplitude signal to be amplified by said FET amplifier stage.
Claim 9
Dependent Claim
22 words
(Amended) The amplifier of claim 1, wherein said reference signal is related to a level of said externally provided variable amplitude signal.
Claim 10
Dependent Claim
95 words
A power amplifier comprising: an PET amplifier stage for amplifying an externally provided variable amplitude signal and having a control terminal; a detector for detecting a power supply current to said FET amplifier stage and providing a signal in response thereto; and a circuit for supplying a control signal to said control terminal of said FET amplifier stage, said control signal being at least partly determined by said signal provided by said detector; wherein said detector comprises a resistance connected between a power supply source and a power supply terminal of said FET amplifier stage.
Claim 11
Dependent Claim
95 words
A power amplifier comprising: an PET amplifier stage for amplifying an externally provided variable amplitude signal and having a control terminal; a detector for detecting a power supply current to said FET amplifier stage and providing a signal in response thereto; and a circuit for supplying a control signal to said control terminal of said FET amplifier stage, said control signal being at least partly determined by said signal provided by said detector; wherein said detector comprises a resistance connected between a power supply source and a power supply terminal of said FET amplifier stage.
Claim 12
Dependent Claim
31 words
The power amplifier of claim 9, wherein said FET amplifier stage has a drain terminal connected to receive said power supply current, and said detector is connected to said drain terminal.
Claim 13
Dependent Claim
101 words
A power amplifier comprising: an FET amplifier stage for amplifying an externally provided variable amplitude signal and having a control terminal; a detector for detecting a power supply current to said FET amplifier stage and providing a signal in response thereto; and a circuit for supplying a control signal to said control terminal of said FET amplifier stage, said control signal being at least partly determined by said signal provided by said detector; wherein said control signal is determined by a signal related to an amplitude of said externally provided variable amplitude signal and by said signal provided by said detector.
Claim 14
Dependent Claim
101 words
A power amplifier comprising: an FET amplifier stage for amplifying an externally provided variable amplitude signal and having a control terminal; a detector for detecting a power supply current to said FET amplifier stage and providing a signal in response thereto; and a circuit for supplying a control signal to said control terminal of said FET amplifier stage, said control signal being at least partly determined by said signal provided by said detector; wherein said control signal is determined by a signal related to an amplitude of said externally provided variable amplitude signal and by said signal provided by said detector.
Claim 15
Dependent Claim
69 words
The amplifier of claim 11, wherein said circuit for supplying said control signal comprises an operational amplifier and wherein said control signal is an output signal of said operational amplifier and wherein said operational amplifier receives two input signals, a first input signal being said signal related to the amplitude of said externally provided variable amplitude signal, and a second input signal being said signal provided by said detector.
Claim 16
Independent Claim
176 words
A method for operating an amplifier for amplifying an externally provided variable amplitude input signal to provide a stable operating point over varying operating conditions and said amplifier having at least one FET amplifier stage, the operating point of said FET amplifier stage being determined by a signal applied to a control terminal of said FET .amplifier stage, the method comprising the steps of: providing said FET amplifier stage as having a particular level of gain corresponding to a particular level of a power supply current to said FET amplifier stage, said particular level of gain being independent of said varying operating conditions; detecting a level of said power supply current to said FET amplifier stage; providing a voltage which is proportional to said power supply current level; providing a reference signal; comparing said reference signal to said proportional voltage and generating a signal in response; and applying the generated signal to said control terminal, wherein the generated signal causes said FET amplifier stage to operate at the stable operating point over said varying operating conditions.
Claim 17
Independent Claim
176 words
A method for operating an amplifier for amplifying an externally provided variable amplitude input signal to provide a stable operating point over varying operating conditions and said amplifier having at least one FET amplifier stage, the operating point of said FET amplifier stage being determined by a signal applied to a control terminal of said FET .amplifier stage, the method comprising the steps of: providing said FET amplifier stage as having a particular level of gain corresponding to a particular level of a power supply current to said FET amplifier stage, said particular level of gain being independent of said varying operating conditions; detecting a level of said power supply current to said FET amplifier stage; providing a voltage which is proportional to said power supply current level; providing a reference signal; comparing said reference signal to said proportional voltage and generating a signal in response; and applying the generated signal to said control terminal, wherein the generated signal causes said FET amplifier stage to operate at the stable operating point over said varying operating conditions.
Claim 18
Dependent Claim
33 words
The method of claim 13, wherein said reference signal is indicative of a predetermined operating point of said FET amplifier stage at a particular level of said externally provided variable amplitude input signal.
Claim 19
Dependent Claim
21 words
The method of claim 13, wherein the step of detecting comprises detecting at a drain terminal of said FET amplifier stage.
Claim 20
Independent Claim
147 words
A method of operating an amplifier for amplifying an externally provided variable amplitude input signal, the amplifier having at least one FET amplifier stage which amplifies said externally provided variable amplitude input signal and having an operating point set by a control signal provided thereto, and having a particular level of gain corresponding to a particular level of a power supply current to said at least one FET amplifier stage, said particular level of gain being independent of operating conditions, the method comprising the steps of: providing a first signal related to a level of said externally provided variable amplitude input signal; providing a second signal related to said gain of said at least one FET amplifier stage; comparing said first and second signals and generating a signal in response; and applying said generated signal to said at least one FET amplifier stage as said control signal.
Claim 21
Independent Claim
147 words
A method of operating an amplifier for amplifying an externally provided variable amplitude input signal, the amplifier having at least one FET amplifier stage which amplifies said externally provided variable amplitude input signal and having an operating point set by a control signal provided thereto, and having a particular level of gain corresponding to a particular level of a power supply current to said at least one FET amplifier stage, said particular level of gain being independent of operating conditions, the method comprising the steps of: providing a first signal related to a level of said externally provided variable amplitude input signal; providing a second signal related to said gain of said at least one FET amplifier stage; comparing said first and second signals and generating a signal in response; and applying said generated signal to said at least one FET amplifier stage as said control signal.
Claim 22
Dependent Claim
114 words
A steady operating point amplifier comprising: an FET amplifier, having a drain terminal for receiving a supply current and for providing an output signal, and having a gate terminal coupled to receive an input signal and coupled to a control voltage; means for providing an indication of a level of said supply current; a terminal receiving a bias control signal indicating a desired operating point of said FET amplifier; and means for comparing said bias control signal to said level indication and producing said control voltage, said control voltage thereby controlling the level of said supply current; wherein a desired operating point of said FET amplifier is maintained constant over variations in operating conditions.
Claim 23
Dependent Claim
114 words
A steady operating point amplifier comprising: an FET amplifier, having a drain terminal for receiving a supply current and for providing an output signal, and having a gate terminal coupled to receive an input signal and coupled to a control voltage; means for providing an indication of a level of said supply current; a terminal receiving a bias control signal indicating a desired operating point of said FET amplifier; and means for comparing said bias control signal to said level indication and producing said control voltage, said control voltage thereby controlling the level of said supply current; wherein a desired operating point of said FET amplifier is maintained constant over variations in operating conditions.
Claim 24
Dependent Claim
31 words
The steady operating point amplifier of claim 17, wherein said input signal has a variable amplitude and said bias control signal is a function of the amplitude of said input signal.
Claim 25
Dependent Claim
50 words
The steady operating point amplifier of claim 17, wherein said desired operating point of said FET amplifier indicates a first level of said supply current at a first amplitude of said input signal and indicates a second level of said supply current at a second amplitude of said input signal.
Claim 26
Dependent Claim
44 words
The steady operating point amplifier of claim 19, wherein said first level of said supply current is greater than said second level of said supply current and said first amplitude of said input signal is greater than said second amplitude of said input signal.
Claim 27
Dependent Claim
30 words
The steady operating point amplifier of claim 17, wherein said desired operating point designates a fixed gain, a fixed current consumption, and a fixed saturation point of said FET amplifier.
References Cited (Backward Citations)
US3514710A
Cited
US4041396A
Cited
US4158180A
Cited
US4320350A
Cited
US4578603A
Cited
US4447783A
Cited
US4510460A
Cited
US4495648A
Cited
US4523155A
Cited
US4593409A
Cited
US4654882A
Cited
US4613990A
Cited
US4709403A
Cited
US4602218A
Cited
US4723304A
Cited
US4870698A
Cited
US4797632A
Cited
US5029298A
Cited
US5083096A
Cited
US5146180A
Cited
US5107225A
Cited
US5132634A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-14 | 1999-02-13 | 1999-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-14 | 2003-02-13 | 2003-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-14 | 2007-02-13 | 2007-08-15 | $7700.00 | Window Closed / Lapsed |