Board Configuration - Analog Devices ADRV9001 User Manual

Reference Manual ADRV9001
DIGITAL PREDISTORTION (DPD)
clgcFilterAlpha
This parameter stands for the coefficient of a single-pole filter to smooth the gain measurement. The minimum value is 0, which is equivalent
to disable this filter by using the instantaneous gain measurement result. The maximum value is 1, and the default value is 0.75. Set the bigger
value to achieve smoother gain measurement results.
clgcLastGain_HundredthdB
This parameter represents the unfiltered gain measurement results when the loop is open. Use API to retrieve this value, which is in an
accuracy of a hundredth of a dB. Note: This parameter is only valid for retrieving.
clgcFilteredGain_HundredthdB
This parameter represents the filtered gain measurement results when the loop opens (based on the user-configured filter coefficient). Use API
to retrieve this value, which is in an accuracy of a hundredth of a dB. Note: This parameter is only valid for retrieving.
captureDelay_us
This parameter delays the DPD capture from the beginning of the transmitter frame by an amount of time (in μs) specified. By default, it is set
to 0. However, It can help avoid using transmitter data at the beginning of a transmitter frame, such as preamble or control signal, which has a
characteristic not suitable for DPD operation. Note: This parameter applies to both DPD and CLGC.
Configure the DPD/CLGC post initial calibration parameters through TES, as shown in Figure 197. Note: All data capture related configurations
such as "Number of Samples," "Capture Delay (us)," "Rx/Tx Normalization", and "Activation" are also used by the CLGC algorithm.
Figure 197. Configuring DPD/CLGC Post Initial Calibration Parameters Through TES

BOARD CONFIGURATION

Besides configuring the DPD/CLGC preinitial and post initial calibration parameters, configure two other parameters related to the board config-
uration: externalLoopbackPeakPower and externalLoopbackPathDelay. Provide these to the ADRV9001 before performing initial calibrations.
externalLoopbackPeakPower
It indicates the peak power of the ORx input signal loop backed from the transmitter output. For the DPD/CLGC to achieve optimal
performance, set the ideal externalLoopbackPeakPower at about -18 dBm with a tolerance of ±5 dBm. Adjust the peak power using an external
step attenuator after the PA.
externalLoopbackPathDelay
DPD/CLGC requires the alignment of the transmit signal capture x(t) with the external loopback capture y(t). The externalLoopbackPathDelay
parameter compensates for additional delays on the external loopback path from the ADRV9001 transmit output to the ORx input. Measure this
delay and provide it to the ADRV9001 before initial calibration. Then use the measured delay to compensate for the delay between x(t) and y(t).
analog.com Rev. 0 | 222 of 351