Dpd/Clgc Api Programming; Dpd Tuning And Testing - Analog Devices ADRV9001 User Manual

Reference Manual
DIGITAL PREDISTORTION (DPD)
Note: In this case, disable immediate LUT switching as the LUT switch only happens at the beginning of each hopping frame with the correct
LUT for that LO frequency. In addition, the length of each hopping frame should be sufficient to capture a specified number of samples at the
DPD sampling rate plus the additional time it takes for the system to set up the DPD tracking calibration. If this condition is not satisfied, DPD
cannot be performed successfully with FH. For example, if the number of samples is set as 4096, for LTE20, the DPD sampling rate is at
184.32 MSPS, and the hopping frame must be longer than 4096/184.32 = 22.22 µs.

DPD/CLGC API PROGRAMMING

A set of API commands set and inspect the DPD/CLGC parameters summarized in
the ADRV9001 initialization structure. Refer to the Doxygen document for more details.
Table 95. DPD APIs
DPD Rx Function Name
adi_adrv9001_dpd_Initial_Configure
adi_adrv9001_dpd_Initial_Inspect
adi_adrv9001_dpd_Configure
adi_adrv9001_dpd_Inspect
adi_adrv9001_dpd_coefficients_Set
adi_adrv9001_dpd_coefficients_Get
adi_adrv9001_dpd_CaptureData_Read
di_adrv9001_dpd_fh_regions_Configure
adi_adrv9001_dpd_fh_regions_Inspect

DPD TUNING AND TESTING

Figure 201 describes an example setup to test the integrated DPD with the ADRV9001 evaluation board in narrowband applications (in
narrowband applications such as TETRA, PA input should be connected to the TX1 output, and PA output should be connected to RX1B).
Figure 201 shows that an LPF is required at the Tx1 output port to filter out the transmitter harmonics before feeding the signal to the PA
driver (If the PA driver has an internal LPF, then the external LPF is not needed). As the device uses a square-wave mixer, it produces
strong odd-order harmonics. Without filtering those harmonics, the DPD performance can be impacted. The step attenuators external to the
ADRV9001 evaluation board are optional. Note: It is important to set up the external loopback path before operating the integrated DPD. To
achieve optimal DPD performance for TETRA waveforms, it is recommended to use an external LO source for the transmitter due to possible
better phase noise performance, while the receiver LO remains internal because the RF receive signal is downconverted to an intermediate
frequency (IF) instead of directly to baseband. For wideband applications, the setup is similar, but both transmitter and receiver LOs can be set
to be internal because a wideband signal is less sensitive to phase noise. Set up a spectrum analyzer to observe the adjacent channel power
ratio (ACPR) performance during a DPD operation.
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Figure 200. Define Frequency Hop Regions Through TES
Description
Configures the preinitial calibration DPD parameters. Called by adi_adrv9001_Utilities_InitRadio_Load() as part of
device initialization.
Inspects the preinitial calibration DPD parameters.
Configures the post-initial calibration DPD parameters.
Inspects the post-initial calibration DPD parameters.
Sets DPD coefficients to be used at the next start of DPD.
Gets DPD coefficients for the last solution.
Reads DPD captured data.
Configures DPD FH frequency regions.
Inspects DPD FH frequency regions.
Table 95. Set the board configuration parameters through
ADRV9001
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