Power amplifier linearization using cancellation-based feed forward methods and systems
First Claim
1. A system for improving linearity of a power amplifier, comprising:
- a first input operable to couple to an input signal path of the power amplifier for obtaining a first sample of an input signal of the power amplifier;
a second input operable to couple to an output signal path of the power amplifier for obtaining a second sample of an output signal of the power amplifier, the second sample comprising at least one sampled non-linearity component corresponding to at least one non-linearity component of the output signal;
an output operable to couple to the output signal path of the power amplifier for applying a linearity improving signal to the output signal path downstream from the second input;
a third input operable to couple to the output signal path at a location downstream from the second input and the output for obtaining a third sample of the output signal; and
a linearizer electrically coupled to the inputs and the output and comprising;
a first signal canceller for deducting the first sample from the second sample to generate an intermediate signal comprising the at least one sampled non-linearity component;
a second signal canceller coupled to an output of the first signal canceller and operable to produce the linearity improving signal by adjusting at least one of an amplitude, a phase, and a delay of the at least one sampled non-linearity component based on a control setting, the linearity improving signal operable to reduce an intensity of the at least one non-linearity component in response to being coupled to the output signal path at the output;
a power detector for measuring an intensity level of at least one of the at least one non-linearity component of the third sample;
a control device that adjusts the control setting of the second signal canceller based on the measured intensity level; and
a second power detector for measuring an intensity of at least one spectral component of the intermediate signal, wherein the control device receives an intensity measurement from the second power detector and adjusts at least one setting of the first signal canceller based on the intensity measurement.
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Accused Products
Abstract
Linearizers can improve the linearity of power amplifiers by canceling or reducing amplitude of non-linearity components, (e.g., IM3, IM5, IM7, IM9, etc.) generated by the power amplifier. The linearizers can obtain samples of signals output by the power amplifier and process the samples to produce a canceling signal that is applied onto or into an output of the power amplifier. The canceling signal is generated such that when applied to the output of the power amplifier, the canceling signal cancels or reduces at least a portion of the non-linearity components produced by the power amplifier. A controller can improve the correction of the non-linearity components by executing one or more tuning algorithms and adjusting settings of the linearizer based on the results of the algorithm(s).
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Citations
27 Claims
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1. A system for improving linearity of a power amplifier, comprising:
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a first input operable to couple to an input signal path of the power amplifier for obtaining a first sample of an input signal of the power amplifier; a second input operable to couple to an output signal path of the power amplifier for obtaining a second sample of an output signal of the power amplifier, the second sample comprising at least one sampled non-linearity component corresponding to at least one non-linearity component of the output signal; an output operable to couple to the output signal path of the power amplifier for applying a linearity improving signal to the output signal path downstream from the second input; a third input operable to couple to the output signal path at a location downstream from the second input and the output for obtaining a third sample of the output signal; and a linearizer electrically coupled to the inputs and the output and comprising; a first signal canceller for deducting the first sample from the second sample to generate an intermediate signal comprising the at least one sampled non-linearity component; a second signal canceller coupled to an output of the first signal canceller and operable to produce the linearity improving signal by adjusting at least one of an amplitude, a phase, and a delay of the at least one sampled non-linearity component based on a control setting, the linearity improving signal operable to reduce an intensity of the at least one non-linearity component in response to being coupled to the output signal path at the output; a power detector for measuring an intensity level of at least one of the at least one non-linearity component of the third sample; a control device that adjusts the control setting of the second signal canceller based on the measured intensity level; and a second power detector for measuring an intensity of at least one spectral component of the intermediate signal, wherein the control device receives an intensity measurement from the second power detector and adjusts at least one setting of the first signal canceller based on the intensity measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for reducing non-linearity components of an output signal of a power amplifier, the method comprising:
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(a) obtaining a first sample of an input signal from a location along an input path of the power amplifier; (b) obtaining a second sample of the output signal from a first location along an output signal path of the power amplifier, the second sample comprising at least one non-linearity component imposed on the power amplifier output signal; (c) generating a first intermediate signal by reducing a spectral component of the second sample by deducting the first sample from the second sample; (d) producing a linearity improving signal by adjusting at least one of a phase, an amplitude, and a delay of the first intermediate signal based on a control setting, the linearity improving signal operable to reduce an amplitude of the at least one non-linearity component in response to being applied to the output signal; (e) applying the linearity improving signal to the output signal at a second location along the output signal path; (f) obtaining a third sample of the output signal from a third location along the output signal path downstream from the second location, the third sample comprising at least one amplitude adjusted non-linearity component corresponding to the at least one non-linearity component; (g) determining an intensity level of the at least one amplitude adjusted non-linearity component in the third sample; and (h) adjusting the control setting based on the intensity level, wherein determining the intensity level of the at least one intermodulation product in the third sample comprises reducing the intensity level of at least one spectral component of the third sample by mixing down and filtering components of the third sample having a frequency at or near baseband for the power amplifier. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system, comprising:
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a signal transmit path comprising an amplifier; a first input configured to receive a first sample comprising an input signal to the amplifier; a second input configured to receive a second sample comprising an output signal from the amplifier; an output configured to feed a linearity improving signal to the amplifier output; a third input configured to receive a third sample comprising the amplifier output from a location along an amplifier output signal path downstream from the second input and the output; and a linearization circuit electrically coupled to the first input, the second input, the third input, and the output, the linearization circuit comprising; a first signal canceling circuit that deducts the first sample from the second sample to produce an intermediate signal; a second signal canceling circuit that generates the output signal by adjusting at least one of a phase, an amplitude, and a delay of the intermediate signal based on a control setting comprising an in-phase setting and a quadrature setting; a controller operable to adjust the control setting comprising the in-phase setting and the quadrature setting based on an intensity level of at least one spectral component of the third sample; and at least one frequency converting mixer disposed between the first input and the first signal canceling circuit, between the second input and the first signal canceling circuit, or between the output and the second canceling circuit. - View Dependent Claims (24, 25, 26, 27)
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Specification