Preliminary Technical Data
UG-1828
Rev. PrC | Page 215 of 338
Measuring the External Path Delay
User could call the following API commands to measure and check the external path delay:
1: adi_adrv9001_cals_ExternalPathDelay_Calibrate(). This API should be called when the channel state is CALIBRATED. It internally
calls the following functions (user does not need to call those 2 lower level APIs).
•
ExternalPathDelay_Run(), which runs external path delay calibrations.
•
ExternalMinusInternalPathDelay_Measure(), which measures and gets the result of the difference in path delays between ILB
and ELB and calculate the delay.
2: adi_adrv9001_cals_ExternalPathDelay_Set(). This API sets the external path delay value measured by
“adi_adrv9001_cals_ExternalPathDelay_Calibrate()”. This API should be call when the Channel state in STANDBY and CALIBRATED
only.
3: adi_adrv9001_cals_ExternalPathDelay_Get(). It gets the current external path delay value. User could use this API to check the delay.
CLGC TARGET GAIN MEASURMENT
The user is responsible to set the gain target for their choice of PA. The gain target can be determined in lab by using a PA with a typical
gain at room temperature. The following guidelines provide optimal operation of ADRV9001. The optimal gain target and adjustable
gains in transmit and external loopback receive should be fixed during operation, except for the transmit attenuation adjustment by
CLGC.
1.
Set the transmit frequency to the middle of the band of interest.
2.
Adjust the peak digital transmit signal amplitude to be between -6 dBFS at the DAC.
o
margin 3 dB
o
Maximum DPD expansion 3 dB
3.
Adjust the transmit attenuator so that the PA input ACPR (before PA) is about -70 dBc.
4.
Connect the amplifier drivers and PA to the RF output
5.
Increase the transmit attenuation so that the peak compression is about 1 dB
6.
If a peak compression of 1 dB cannot be reached, increase the gain of an amplifier driver.
7.
Adjust the gain of the external loopback path to make the feedback signal peak amplitude to be around -18dBm with a
tolerance of ±5dB .
8.
These settings should not be changed during normal operation. Otherwise, a new gain target should be determined.
9.
Use TES to measure the transmit gain to help determine the gain target. To do this, user should enable “CLGC Loop Open”
option under “Digital Pre-Distortion” tab in TES as shown in the plot below. Then user should play a Tx modulated input
signal and observe the “CLGC last gain” and “CLGC filtered gain” at the “Transmit” tab. Note the a single pole filter can be
applied to smooth the gain measurement and user could set the filter coefficient (0<α<1) as shown in Figure 200. The
mesurment is smoother when bigger α is used. By default, it is set as 0.75.
Figure 200. CLGC Configuration Parameters
10.
By determining the final gain target based on the “CLGC last gain” and “CLGC filtered gain” provided by ADRV9001, user
should configure “CLGC Gain Target” as shown in the above figure. After that user should disable “CLGC Loop Open” to
close the loop to allow CLGC to achieve the gain target. Note if the transmit attenuation is changed by anything else rather
than the CLGC, the change must be factored in the gain target. To achieve the most accurate gain control, the gain variation
of the external components and ORx data path components should also be compensated by adjusting the gain target.