Transmitter Linearized In Response To Signal Magnitude Derivative Parameter 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 said method comprising:
- providing a communication signal;
producing a gain-correcting signal responsive to a magnitude parameter of said communication signal and a magnitude derivative parameter of said communication signal;
adjusting gain of said 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
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Accused Products
Abstract
A transmitter (50) includes a low power nonlinear predistorter (58) that inserts predistortion configured to compensate for a memoryless nonlinearity (146) corresponding to gain droop and another memoryless nonlinearity (148) corresponding to a video signal. 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). A look-up table (282) has address inputs responsive to a magnitude parameter (152) of a communication signal (54), a magnitude derivative parameter (204) of the communication signal (54), and possibly one or more variable bias parameters (85). The look-up table (282) produces a gain-correcting signal (284) that adjusts the gain applied to the communication signal (54) prior to amplification. The look-up table (282) is updated in response to an LMS control loop.
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Citations
26 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 said method comprising:
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providing a communication signal; producing a gain-correcting signal responsive to a magnitude parameter of said communication signal and a magnitude derivative parameter of said communication signal; adjusting gain of said 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, 10, 11, 12, 13)
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14. A linearized transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier, said transmitter comprising:
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a communication signal source configured to produce a communication signal; and a polynomial generator having an input coupled to said communication signal source, said polynomial generator being responsive to a magnitude parameter of said communication signal and a magnitude derivative parameter of said communication signal, and said polynomial generator having an output producing a gain-correcting signal; 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 (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of linearizing a transmitter having an amplifier which applies a nonlinear amplifier transform to a signal input at said amplifier said method comprising:
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configuring a network of components coupled to said amplifier to exhibit an impedance to said amplifier that either remains constant with increasing frequency or increases with increasing frequency throughout a video signal bandwidth; providing a communication signal; determining a magnitude parameter of said communication signal; taking a derivative with respect to time of said magnitude parameter to form a magnitude derivative parameter; producing a gain-correcting signal using a look-up table having a first address input responsive to said magnitude parameter and having a second address input responsive to said magnitude derivative parameter; adjusting gain of said 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.
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Specification