Multi-band linearization system

A system for digital predistortion of multiband signals, the system comprising:

• a power amplification system comprising a transmit chain including at least a power amplifier that produces output with non-linear distortions, wherein the non-linear distortions of the transmit chain are represented using a set of basis functions derived
• according to a single-band model of the non-linear distortions;
• and a controller to perform digital predistortion on signal components derived from multiple signal portions of an input signal using a reduced set of the basis functions that excludes at least some basis functions for at least some cross-terms resulting from a full expansion of the single-band model of the non-linear distortions applied to the multiple signal portions, to produce a digital predistorted signal provided to the transmit chain;
• wherein the controller configured to perform the digital predistortion is configured to compute digital predistortion coefficients to weight the reduced set of basis functions, including to derive a first group of coefficients for a first group of the basis function terms operating on input values of the signal components, a second group of coefficients for a second group of basis function terms operating on normalized input values of the signal components, and a third group of coefficients for a third group of basis function terms operating on input values of combinations of the signal components.

A design structure encoded on a non-transitory machine-readable medium,

• said design structure comprising elements that to be processed in a computer-aided design system, to generate a machine-executable representation of a multiband predistorter, the multiband predistorter comprising:
• a power amplification circuit comprising a transmit chain including at least a power amplifier that produces output with non-linear distortions, wherein the non-linear distortions of the transmit chain are represented using a set of basis functions derived according to a single-band model of the non-linear distortions;
• and a control circuit to perform digital predistortion on signal components derived from multiple signal portions of an input signal using a reduced set of the basis functions that excludes at least some basis functions for at least some cross-terms resulting from a full expansion of the single-band model of the non-linear distortions applied to the multiple signal portions, to produce a digital predistorted signal provided to the transmit chain;
• wherein the control circuit configured to perform the digital predistortion is configured to compute digital predistortion coefficients to weight the reduced set of basis functions, including to derive a first group of coefficients for a first group of the basis function terms operating on input values of the signal components, a second group of coefficients for a second group of basis function terms operating on normalized input values of the signal components, and a third group of coefficients for a third group of basis function terms operating on input values of combinations of the signal components.

A non-transitory computer readable media programmed with instructions, executable on a processor, to:

• receive an input signal comprising multiple signal portions in different frequency bands, the input signal configured to be processed by a transmit chain of a power amplification system with the transmit chain comprising at least a power amplifier that produces output with non-linear distortions, wherein the non-linear distortions of the transmit chain are represented using a set of basis functions derived according to a single-band model of the non-linear distortions;
• and
• perform digital predistortion on signal components derived from the multiple signal portions of the input signal using a reduced set of the basis functions that excludes at least some basis functions for at least some cross-terms resulting from a full expansion of the single-band model of the non-linear distortions applied to the multiple signal portions, to produce a digital predistorted signal provided to the transmit chain;
• wherein the instructions to perform the digital predistortion include one or more instructions to compute digital predistortion coefficients to weight the reduced set of basis functions, including to derive a first group of coefficients for a first group of the basis function terms operating on input values of the signal components, a second group of coefficients for a second group of basis function terms operating on normalized input values of the signal components, and a third group of coefficients for a third group of basis function terms operating on input values of combinations of the signal components.

A method for digital predistortion of multiband signals, the method comprising:

• receiving an input signal comprising multiple signal portions in different frequency bands, the input signal configured to be processed by a transmit chain of a power amplification system with the transmit chain comprising at least a power amplifier that produces output with non-linear distortions, wherein the non-linear distortions of the transmit chain are represented using a set of basis functions derived according to a single-band model of the non-linear distortions;
• and
• performing digital predistortion on signal components derived from the multiple signal portions of the input signal using a reduced set of the basis functions that excludes at least some basis functions for at least some cross-terms resulting from a full expansion of the single-band model of the non-linear distortions applied to the multiple signal portions, to produce a digital predistorted signal provided to the transmit chain;
• wherein the signal components comprise individual normalized parts of the multiple signal portions;
• and wherein the method further includes computing the individual normalized parts of the multiple signal portions according to:
• w
• j
• =
• x
• j
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• 1
• (
• ∑
• k
• =
• 1
• n
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• p
• wherein xj is one of n individual parts of the multiple signal portions of the input signal, and wherein p includes a fractional exponent selected to yield good performance for an output of the transmit chain resulting from the produced digital predistorted signal.

A system for digital predistortion of multiband signals, the system comprising:

• a power amplification system comprising a transmit chain including at least a power amplifier that produces output with non-linear distortions, wherein the non-linear distortions of the transmit chain are represented using a set of basis functions derived according to a single-band model of the non-linear distortions;
• and a controller to perform digital predistortion on signal components derived from multiple signal portions of an input signal using a reduced set of the basis functions that excludes at least some basis functions for at least some cross-terms resulting from a full expansion of the single-band model of the non-linear distortions applied to the multiple signal portions, to produce a digital predistorted signal provided to the transmit chain;
• wherein the signal components comprise individual normalized parts of the multiple signal portions;
• and wherein the controller is further configured to compute the individual normalized parts of the multiple signal portions according to:
• w
• j
• =
• x
• j
• ⁢
• 1
• (
• ∑
• k
• =
• 1
• n
• ⁢
• 
• x
• k
• 
• 2
• )
• p
• wherein xj is one of n individual parts of the multiple signal portions of the input signal, and wherein p includes a fractional exponent selected to yield good performance for an output of the transmit chain resulting from the produced digital predistorted signal.