Obtaining reliable and specific data for adaptive digital predistortion
Systems, devices, and methods related to performing digital predistortion in radio frequency (RF) systems are provided. A digital predistortion (DPD) arrangement includes a DPD actuator circuit to predistort, using DPD coefficients, at least a portion of an input signal, the DPD coefficients associated with a characteristic of a nonlinear component. The DPD arrangement further includes a DPD capture circuit to perform, based on a capture cycle timing, multiple captures of a feedback signal, the feedback signal indicative of an output of the nonlinear component; compute, based on one or more characteristics of the multiple captures, one or more criteria for a subsequent capture of the feedback signal; and perform, based on the one or more criteria, the subsequent capture of the feedback signal. The DPD arrangement circuit further includes a DPD adaptation circuit to update the DPD coefficients based at least in part on the subsequent capture.
1. A digital predistortion (DPD) system with multi-mode capture, the DPD system comprising:
a DPD actuator circuit to predistort at least a portion of an input signal using DPD coefficients, the DPD coefficients associated with a nonlinear component;
a multi-mode DPD capture circuit to acquire one or more captures of a feedback signal, the multi-mode DPD capture circuit operable in a plurality of modes, and the feedback signal indicative of an output signal of the nonlinear component; and
a DPD adaptation circuit to update the DPD coefficients based at least in part on the one or more captures.
2. The DPD system of claim 1 , wherein the DPD adaptation circuit is to combine captures from at least two different modes of the plurality of modes.
3. The DPD system of claim 1 , wherein the plurality of modes comprises a mode where the multi-mode DPD capture circuit places a peak sample power of a capture window substantially in a center of a capture buffer.
4. The DPD system of claim 3 , wherein the plurality of modes comprises another mode where the multi-mode DPD capture circuit synchronizes a peak window start with a frame at a programmed offset, and a capture is centered at the peak sample power that is within the peak window.
5. The DPD system of claim 3 , wherein the plurality of modes comprises another mode where the multi-mode DPD capture circuit decimates data prior to storing the one or more captures.
6. The DPD system of claim 3 , wherein the plurality of modes comprises another mode where the multi-mode DPD capture circuit accumulates samples over multiple captures to perform averaging.
7. The DPD system of claim 1 , wherein the plurality of modes comprises a mode where the multi-mode DPD capture circuit synchronizes a peak window start with a frame at a programmed offset.
8. The DPD system of claim 7 , wherein the plurality of modes comprises another mode where the multi-mode DPD capture circuit decimates data prior to storing the one or more captures.
9. The DPD system of claim 1 , wherein the plurality of modes comprises a mode where the multi-mode DPD capture circuit decimates data prior to storing the one or more captures in one or more capture buffers.
10. The DPD system of claim 1 , wherein the plurality of modes comprises a mode where the multi-mode DPD capture circuit accumulates samples over multiple captures to perform averaging.
11. The DPD system of claim 1 , wherein the plurality of modes comprises at least two of:
a first mode where the multi-mode DPD capture circuit places a peak sample power of a capture window substantially in a center of a capture buffer;
a second mode where the multi-mode DPD capture circuit synchronizes a peak window start with a frame at a programmed offset;
a third mode where the multi-mode DPD capture circuit decimates data prior to storing the one or more captures;
a fourth mode where the multi-mode DPD capture circuit performs multiple capture cycles to compute one or more characteristics of data and set one or more thresholds for subsequent captures; or
a fifth mode where the multi-mode DPD capture circuit accumulates samples over multiple captures to perform averaging.
12. A radio frequency (RF) device comprising:
a nonlinear component;
a digital predistortion (DPD) actuator circuit to predistort at least a portion of an input signal using DPD coefficients, the DPD coefficients associated with the nonlinear component;
a multi-mode DPD capture circuit to acquire captures of a feedback signal associated with at least two different modes of a plurality of modes, and the feedback signal indicative of an output signal of the nonlinear component; and
a DPD adaptation circuit to update the DPD coefficients based at least in part on the captures.
13. The RF device of claim 12 , wherein the plurality of modes comprises at least two of:
a first mode where the multi-mode DPD capture circuit places a peak sample power of a capture window substantially in a center of a capture buffer;
a second mode where the multi-mode DPD capture circuit synchronizes a peak window start with a frame at a programmed offset;
a third mode where the multi-mode DPD capture circuit decimates data prior to storing the captures;
a fourth mode where the multi-mode DPD capture circuit where the multi-mode DPD capture circuit performs multiple capture cycles to compute one or more characteristics of data and set one or more thresholds for subsequent captures; or
a fifth mode where the multi-mode DPD capture circuit accumulates samples over multiple captures to perform averaging.
14. The RF device of claim 12 , wherein the nonlinear component comprises a power amplifier.
15. The RF device of claim 12 , wherein the RF device is a mobile device.
16. The RF device of claim 12 , wherein the RF device is a base station.
17. A method of digital predistortion (DPD) with multi-mode capture, the method comprising:
capturing, using a multi-mode DPD capture circuit, a feedback signal in a first mode, the feedback signal indicative of an output of a nonlinear component;
capturing, using the multi-mode DPD capture circuit, the feedback signal in a second mode, the second mode being different than the first mode;
updating, using a DPD adaptation circuit, DPD coefficients associated with the nonlinear component based at least in part on the capturing the feedback signal in the first mode and the capturing the feedback signal in the second mode; and
predistorting, using a DPD actuator circuit, at least a portion of an input signal based on the DPD coefficients from the updating.
18. The method of claim 17 , wherein the multi-mode DPD capture circuit places a peak sample power of a capture window substantially in a center of a capture buffer in the first mode.
19. The method of claim 18 , wherein the multi-mode DPD capture circuit synchronizes a peak window start with a frame at a programmed offset in the second mode.
20. The method of claim 18 , wherein the multi-mode DPD capture circuit accumulates samples over multiple captures to perform averaging in the second mode.