Transmitter Linearized Using Bias Deviation Gain Adjustment And Method Therefor
First Claim
1. A method of linearizing a transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier while operating at a variety of bias conditions characterized by an average bias condition and deviations from said average bias condition, said deviations being caused at least in part by said amplifier applying said nonlinear amplifier transform to said signal input at said amplifier, and said method comprising:
- generating a gain-correcting signal responsive to said deviations from said average bias condition;
adjusting gain of a communication signal in response to said gain-correcting signal to form a predistorted communication signal; and
forming said signal input at said amplifier from said predistorted communication signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A transmitter (50) includes a low power memoryless nonlinear predistorter (58) that inserts predistortion configured to address a nonlinearity (146) corresponding to gain droop and another nonlinearity (148) corresponding to deviations from an average bias condition. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). Each nonlinearity is addressed by applying gain to a communication signal (54). The amount of gain applied is determined by a look-up table (170) for one nonlinearity (146) and by a look-up table (198) in combination with a differentiator (202) for the other nonlinearity (148). The look-up tables (170, 198) are updated in accordance with modified LMS control loops.
47 Citations
34 Claims
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1. A method of linearizing a transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier while operating at a variety of bias conditions characterized by an average bias condition and deviations from said average bias condition, said deviations being caused at least in part by said amplifier applying said nonlinear amplifier transform to said signal input at said amplifier, and said method comprising:
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generating a gain-correcting signal responsive to said deviations from said average bias condition; adjusting gain of a communication signal in response to said gain-correcting signal to form a predistorted communication signal; and forming said signal input at said amplifier from said predistorted communication signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A linearized transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier while operating at a variety of bias conditions characterized by an average bias condition and deviations from said average bias condition, said deviations being caused at least in part by said amplifier applying said nonlinear amplifier transform to said signal input at said amplifier, and said transmitter comprising:
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a processing section configured to produce a gain-correcting signal responsive to a communication signal and responsive to said deviations from said average bias condition; and a gain-adjusting section configured to generate a predistorted communication signal in which gain is applied to said communication signal in response to said gain-correcting signal; wherein said signal input at said amplifier is formed from said predistorted communication signal. - View Dependent Claims (13, 14, 15, 16)
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11. A linearized transmitter as claimed in claim 10 wherein said processing section comprises:
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a polynomial generator responsive to said communication signal; and a differentiator coupled to said polynomial generator. - View Dependent Claims (12)
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11-1. (canceled)
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17. A linearized transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier, said nonlinear amplifier transform having a first memoryless component and a second memoryless component, said linearized transmitter comprising:
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a first processing section responsive to a communication signal and configured to generate a first gain-correcting signal by applying a first transform which corresponds to said first memoryless component of said nonlinear amplifier transform; a second processing section responsive to said communication signal and configured to generate a second gain-correcting signal contemporaneous with said first gain-correcting signal by applying a second transform which corresponds to said second memoryless component of said nonlinear amplifier transform; and a joining section responsive to said communication signal and to said first and second gain-correcting signals and configured to generate a predistorted communication signal in which gain is applied to said communication signal in response to said first and second gain-correcting signals; wherein said signal input at said amplifier is formed from said predistorted communication signal. - View Dependent Claims (18, 19, 20, 21, 23, 24, 25, 26, 27, 33)
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28. A method of linearizing a transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier which couples to a network of components exhibiting an inductive impedance, said method comprising:
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generating a gain-correcting signal responsive to a derivative of said communication signal; adjusting gain of a communication signal in response to said gain-correcting signal to form a predistorted communication signal; and forming said signal input at said amplifier from said predistorted communication signal. - View Dependent Claims (29, 30, 31, 32)
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34. A method of linearizing a transmitter having an amplifier which applies a nonlinear amplifier transform exhibiting a memoryless effect and a thermal memory effect to a signal input at said amplifier, said method comprising:
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generating a gain-correcting signal responsive to a communication signal and to said memoryless effect of said nonlinear amplifier transform; adjusting gain of said communication signal in response to said gain-correcting signal to form a predistorted communication signal; normalizing gain of said predistorted communication signal in an automatic gain control section to generate a gain-normalized communication signal; updating said automatic gain control section using a control loop having a loop bandwidth configured to track said thermal memory effect of said nonlinear amplifier transform; and forming said signal input at said amplifier from said gain-normalized communication signal.
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Specification