Interpolation-based digital pre-distortion architecture
First Claim
1. A signal-processing system that generates an analog output signal from a digital input signal, each digital signal in the system having a corresponding sample rate, the system comprising:
- a digital pre-distortion (DPD) sub-system configured to perform DPD processing to generate a final pre-distorted digital signal from the digital input signal, wherein the DPD sub-system interpolates the digital input signal based on an interpolation factor greater than one prior to performing the DPD processing;
a digital-to-analog converter (DAC) configured to convert the final pre-distorted digital signal into an analog pre-distorted signal; and
an analog sub-system configured to generate the analog output signal from the analog pre-distorted signal, wherein the DPD sub-system comprises;
a pre-DPD processor configured to generate one or more versions of the digital input signal, wherein the pre-DPD processor is configured to apply at least one interpolation filter based on the interpolation factor to the digital input signal to generate at least one version of the digital input signal;
a digital pre-distorter configured to pre-distort the one or more versions of the digital input signal to generate one or more intermediate pre-distorted digital signals; and
a post-DPD processor configured to generate the final pre-distorted digital signal from the one or more intermediate pre-distorted digital signals.
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Abstract
A non-linear amplifier is linearized using interpolation-based digital pre-distortion (DPD). In one embodiment, the digital input signal is interpolated to generate a higher-sample-rate signal that is then pre-distorted. The resulting higher-sample-rate pre-distorted signal is then decimated to generate a final pre-distorted digital signal that is converted into an analog pre-distorted signal by a digital-to-analog converter (DAC) before being applied to the amplifier. In a polyphase embodiment, different versions of the original input digital signal are generated, where each version is then pre-distorted using a different DPD module to generate a different intermediate pre-distorted digital signal. The intermediate pre-distorted signals are filtered and combined to generate the final pre-distorted digital signal. In both embodiments, better linearization (e.g., less aliasing) can be achieved without increasing the sample rate of the DAC and, in the polyphase embodiment, without increasing the processing speed of the DPD modules.
23 Citations
16 Claims
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1. A signal-processing system that generates an analog output signal from a digital input signal, each digital signal in the system having a corresponding sample rate, the system comprising:
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a digital pre-distortion (DPD) sub-system configured to perform DPD processing to generate a final pre-distorted digital signal from the digital input signal, wherein the DPD sub-system interpolates the digital input signal based on an interpolation factor greater than one prior to performing the DPD processing; a digital-to-analog converter (DAC) configured to convert the final pre-distorted digital signal into an analog pre-distorted signal; and an analog sub-system configured to generate the analog output signal from the analog pre-distorted signal, wherein the DPD sub-system comprises; a pre-DPD processor configured to generate one or more versions of the digital input signal, wherein the pre-DPD processor is configured to apply at least one interpolation filter based on the interpolation factor to the digital input signal to generate at least one version of the digital input signal; a digital pre-distorter configured to pre-distort the one or more versions of the digital input signal to generate one or more intermediate pre-distorted digital signals; and a post-DPD processor configured to generate the final pre-distorted digital signal from the one or more intermediate pre-distorted digital signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification