Test environment: AD90255GNR signal,FDD working mode, all RX links closed, all TX links open, signal bandwidth 100MHz, central frequency point 3.65g.
Test result: DPD of TX1 and TX3 works normally, DPD of TX2 and TX4 does not.
Problem 1: The DPD calibration of link TX2 and link TX4 does not work, does not converge, and ACPR always remains uncalibrated ACPR=-33dB.
(1) TX2 link, the output power is 23dbm, and the READ DPD status is shown in the figure below: THE DPD feedback data shows that the DPD calibration coefficient is not updated due to the poor EVM.
After instrument test, the EVM of TX2 output is 3.1%, and that of ORX2 input is 3.36% without DPD.
TX4 is the same. This shows that the hardware is fine.
For help 1：Direct EVM, Indirect EVM, Indirect Error, Select Error is too large. How to reduce it? How can I make TX2 and TX4 work?
Problem 2: TX1 and TX3 can work normally, but the first DPD convergence time is not fixed, sometimes fast and sometimes slow, the fastest 15s, the slowest 10mins.
For help 2: What parameters can be set to shorten the first DPD convergence time?
Problem 3:When TX1 and TX3 DPD are working normally, ACPR deteriorates (from -51dB to -41dB) when the output power of TX1 or TX3 is changed. DPD convergence speed is slow, and it takes 1 minute to recover to -51dB.
For Help 3: Which parameters can be changed so that DPD can quickly converge?
Problem 4:In TX1 link DPD function normal calibration state, using "adi_adrv9025_DpdReset" and reset DPD, TX1 link output signal has no response, read TX1 DPD status value, dpDUpDatecount value is not recalculated.Why？