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Wideband Digital Predistortion
| Content Provider | The Lens |
|---|---|
| Abstract | Various examples are directed to systems and methods for wideband digital predistortion. A digital pre-distortion circuit may be programmed to receive a complex baseband signal and generate a pre-distorted signal. Generating the pre -distorted signal may comprise applying to the complex baseband signal a first correction for an Nth order distortion of a power amplifier at an Ith harmonic frequency zone centered at about an Ith harmonic of a carrier frequency and applying to the complex baseband signal a second correction for the Nth order distortion at a Jth harmonic frequency zone centered at about a Jth harmonic of the carrier frequency different than the Ith harmonic of a carrier frequency. |
| Related Links | https://www.lens.org/lens/patent/010-715-359-598-814/frontpage |
| Language | English |
| Publisher Date | 2019-03-05 |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Patent |
| Jurisdiction | United States of America |
| Date Applied | 2016-05-19 |
| Agent | Schwegman Lundberg & Woessner, P.a. |
| Applicant | Analog Devices Global |
| Application No. | 201615159492 |
| Claim | A system comprising: a digital pre-distortion circuit configured to: receive a complex baseband signal; and generate a pre-distorted signal, the generating of the pre-distorted signal comprising: applying to the complex baseband signal a first correction for an N th order distortion of a power amplifier at an I th harmonic frequency zone centered at about an I th harmonic of a carrier frequency; and applying to the complex baseband signal a second correction for the N th order distortion at a J th harmonic frequency zone centered at about a J th harmonic of the carrier frequency different than the I th harmonic of the carrier frequency. The system of claim 1 , wherein the digital pre-distortion circuit is further configured to: determine a value for a first complex basis function for the N th order distortion at the I th harmonic frequency zone based at least in part on the complex baseband signal; determine a value for a second complex basis function for the N th order distortion at the I th harmonic frequency zone based at least in part on the complex baseband signal; apply a first filter to generate a first filter response based at least in part on the value for the first complex basis function; and apply a second filter to generate a second filter response based at least in part on the value for the second complex basis function. The system of claim 2 , wherein the digital pre-distortion circuit is further configured to before determining the value for the first complex basis function, translate the first complex basis function by the carrier frequency. The system of claim 2 , wherein the digital pre-distortion circuit is further configured to: receive a complex feedback signal based at least in part on an output of the power amplifier; compare the complex feedback signal to the pre-distorted signal; and determine a coefficient for the first filter based at least in part on the compare of the complex feedback signal to the pre-distorted signa The system of claim 2 , wherein the digital pre-distortion circuit is further configured to: generate a feedback matrix based at least in part on a complex feedback signal; generate a first an harmonic frequency zone basis vector based at least in part on the value for the first complex basis function; generate a second harmonic frequency zone basis vector based at least in part on the value for the second complex basis function; generate a basis matrix comprising the first frequency zone basis vector and the second frequency zone basis vector; determine a coefficient for the first filter based at least in part on the basis matrix to the feedback matrix. The system of claim 2 , wherein the value for the first complex basis function is based at least in part on a first value of the complex baseband signal at a first time, wherein the digital pre-distortion circuit is further configured to: apply a first tap of the first filter to the first value of the complex baseband signal at the first time; and apply a second tap of the first filter to a second value of the complex baseband signal at a second time that is before the first time. The system of claim 1 , wherein the digital pre-distortion circuit is further configured to: determine a first magnitude of the complex baseband signal at a first time; generate an I th harmonic frequency zone output based at least in part on a first LUT value from a first tap LUT; and generate a Jth harmonic frequency zone output based at least in part on a second LUT value from the first tap LUT. The system of claim 1 , wherein the digital pre-distortion circuit is further configured to: generate an I th harmonic frequency zone exponent for the I th harmonic frequency zone based at least in part on the N th order distortion of the power amplifier; generate a I th harmonic frequency zone multiplier based at least in part on the harmonic frequency zone exponent; select a LUT value from a first tap LUT of the I th harmonic frequency zone based at least in part on a first magnitude of the complex baseband signal at a first time; generate a first tap LUT product for the I th harmonic frequency zone based at least in part on the LUT value and the I th harmonic frequency zone multiplier; and generate an I th harmonic t frequency zone output based at least in part on the first tap LUT product for the I th harmonic frequency zone and an I th harmonic frequency zone carrier component; determine a value for a first complex basis function for the N th order distortion of the power amplifier at a J th harmonic frequency zone, wherein the first complex basis function is based at least in part on the complex baseband signal; and apply a first filter to generate a first response based at least in part on the value for the first complex basis function. The system of claim 1 , wherein the digital pre-distortion circuit is further configured to up-sample the complex baseband signal to generate an up-sampled complex baseband signal, wherein the applying of the first correction and the applying of the second correction is based at least in part on the up-sampled baseband signa The system of claim 1 , wherein the digital pre-distortion circuit is further configured to: up-sample the complex baseband signal to an up-sampled frequency generate an up-sampled complex baseband signal, wherein the pre-distorted signal is at the up-sampled frequency; determine a real component of the pre-distorted signal; and apply a Hilbert transform to the real component of the pre-distorted signa The system of claim 1 , wherein the generating of the pre-distorted signal further comprises: up-sampling the complex baseband signal to generate an up-sampled complex baseband signal, wherein the applying the first correction and the applying the second correction are based at least in part on the up-sampled complex baseband signal; and applying to the complex baseband signal a third correction for a 1 st order term of the power amplifier at a K th harmonic frequency zone centered at the carrier frequency based at least in part on the complex baseband signa The system of claim 1 , wherein the J th harmonic frequency zone is the highest frequency zone corrected by the digital pre-distortion circuit, and wherein N is greater than J. The system of claim 7 , wherein the digital pre-distortion circuit is further configured to: receive a complex feedback signal based at least in part on an output of the power amplifier; compare the complex feedback signal to the pre-distorted signal; and populate the first tap LUT based at least in part on the comparing. The system of claim 7 , wherein the digital-pre-distortion circuit is further configured to: generated an I th harmonic frequency zone exponent based at least in part on an the N th order distortion of the power amplifier; generated an I th harmonic frequency zone multiplier for the first time based at least in part on the I th harmonic frequency zone exponent; select the first LUT value from a first tap LUT of the I th harmonic frequency zone based at least in part on the first magnitude of the complex baseband signal; and generate a first tap LUT product for the I th harmonic frequency zone based at least in part on the first LUT value and the I th harmonic frequency zone multiplier for the first time, wherein the I th harmonic frequency zone output is based at least in part on the first tap LUT product for the I th harmonic frequency zone and an I th harmonic frequency zone carrier component. The system of claim 14 , wherein the generate of the I th harmonic frequency zone multiplier for the first time comprises raising a first value of the complex baseband signal at the first time to the I th harmonic frequency zone exponent. The system of claim 14 , wherein the generate of the first tap LUT product for the I th harmonic frequency zone comprises multiplying the first LUT value and the harmonic frequency zone multiplier. The system of claim 14 , wherein the digital pre-distortion circuit is further configured to, for the I th harmonic frequency zone: determine a second magnitude of the complex baseband signal at a second time before the first time; generate an I th harmonic frequency zone multiplier for the second time based at least in part on the I th harmonic frequency zone exponent and a second value of the complex baseband signal at the second time; select a third look up table (LUT) value from a second tap LUT of the I th harmonic frequency zone based at least in part on the second magnitude of the complex baseband signal; and generate a second tap LUT product for the I th harmonic frequency zone based at least in part on the third LUT value and the I th harmonic frequency zone multiplier for the second time, wherein the I th harmonic frequency zone output is also based at least on part on the second tap LUT product. A method comprising: receiving a complex baseband signal; and generating a pre-distorted signal, wherein the generating comprises: applying to the complex baseband signal a first correction for an N th order distortion of a power amplifier at an I th harmonic frequency zone centered at about an I th harmonic of a carrier frequency; and applying to the complex baseband signal a second correction for the N th order distortion at a J th harmonic frequency zone centered at about a J th harmonic of the carrier frequency different than the I th harmonic of the carrier frequency. The method of claim 18 , further comprising: determining a value for a first complex basis function for the N th order distortion at the I th harmonic frequency zone based at least in part on the complex baseband signal; determining a value for a second complex basis function for the N th order distortion at the I th harmonic frequency zone based at least in part on the complex baseband signal; applying a first filter to generate a first filter response based at least in part on the value for the first complex basis function; and applying a second filter to generate a second filter response based at least in part on the value for the second complex basis function. The method of claim 18 , further comprising: determining a first magnitude of the complex baseband signal at a first time; for the I th harmonic frequency zone: generating an I th harmonic frequency zone exponent based at least in part on an the N th order distortion of the power amplifier; generating an I th harmonic frequency zone multiplier for the first time based at least in part on the I th harmonic frequency zone exponent; selecting a first look up table (LUT) value from a first tap LUT of the I th harmonic frequency zone based at least in part on the first magnitude of the complex baseband signal; generating a first tap LUT product for the I th harmonic frequency zone based at least in part on the first LUT value and the I th harmonic frequency zone multiplier for the first time; and generating an I th harmonic frequency zone output based at least in part on the first tap LUT product for the I th harmonic frequency zone and an I th harmonic frequency zone carrier component; for the J th harmonic frequency zone: generating a J th harmonic frequency zone exponent based at least in part on the N th order distortion of the power amplifier generating a J th harmonic frequency zone multiplier based at least in part on the Jth harmonic frequency zone exponent; selecting a second LUT value from a first tap LUT of the J th harmonic frequency zone based at least in part on the first magnitude of the complex baseband signal; generating a first tap LUT product for the J th harmonic frequency zone based at least in part on the second LUT value and the J th harmonic frequency zone multiplier; and generating a J th harmonic frequency zone output based at least in part on the first tap LUT product for the J th harmonic frequency zone and a J th harmonic frequency zone carrier component. The method of claim 18 , further comprising: generating an harmonic frequency zone exponent for the I th harmonic frequency zone based at least in part on the N th order distortion of the power amplifier; generating a I th harmonic frequency zone multiplier based at least in part on the I th harmonic frequency zone exponent; selecting a LUT value from a first tap LUT of the I th harmonic frequency zone based at least in part on a first magnitude of the complex baseband signal at a first time; generating a first tap LUT product for the I th harmonic frequency zone based at least in part on the LUT value and the harmonic frequency zone multiplier; and generating an I th harmonic t frequency zone output based at least in part on the first tap LUT product for the I th harmonic frequency zone and an I th harmonic frequency zone carrier component; determining a value for a first complex basis function for the N th order distortion of the power amplifier at a J th harmonic frequency zone, wherein the first complex basis function is based at least in part on the complex baseband signal; and applying a first filter to generate a first response based at least in part on the value for the first complex basis function. A digital predistortion system comprising: means for receiving a complex baseband signal; and means for generating a pre-distorted signal, the generating of the pre-distorted signal comprising: applying to the complex baseband signal a first correction for an N th order distortion of a power amplifier at an I th harmonic frequency zone centered at about an I th harmonic of a carrier frequency; and applying to the complex baseband signal a second correction for the N th order distortion at a J th harmonic frequency zone centered at about a J th harmonic of the carrier frequency different than the I th harmonic of the carrier frequency. |
| CPC Classification | TRANSMISSION OF DIGITAL INFORMATION; e.g. TELEGRAPHIC COMMUNICATION AMPLIFIERS TRANSMISSION |
| Examiner | Vineeta S Panwalkar |
| Extended Family | 135-168-074-404-433 022-232-747-072-83X 010-715-359-598-814 158-403-227-412-939 |
| Patent ID | 10224970 |
| Inventor/Author | Pratt Patrick |
| IPC | H04B1/04 H04L25/03 |
| Status | Active |
| Owner | Analog Devices Global Unlimited Company Analog Devices International Unlimited Company |
| Simple Family | 135-168-074-404-433 022-232-747-072-83X 010-715-359-598-814 158-403-227-412-939 |
| CPC (with Group) | H04L25/49 H03F1/3247 H03F1/3258 H04B1/0475 H04B2001/0425 H04L25/03159 H04L25/03343 H04L2025/03356 |
| Issuing Authority | United States Patent and Trademark Office (USPTO) |
| Kind | Patent/New European patent specification (amended specification after opposition procedure) |
