We are developing 5G O-RAN RU and are inquiring as the following problem occurred while testing the DPD of ADRV9025 (CFR is not applied, please refer to attached file)
In TM3.1a (256QAM), DPD operates normally and ACLR characteristics are also good. However, the ACLR characteristics in TM1.1 (QPSK) are very poor. So, when I checked the PAPR at the output of ADRV9025, TM3.1a was 10.2dB (@0.001%) and TM1.1 was 11.5dB (@0.001%).
1. I understand that the subcarriers of TM3.1a and TM1.1 are the same.
In the same case, shouldn't the PAPR of TM3.1a be higher?
Why is the PAPR of TM1.1 measured high?
2. I think ACLR should improve if I lower the output due to the PAPR of TM1.1, but ACLR does not improve even if I lower the output..
3. Can the ACLR performance of TM1.1 be improved if CFR is applied?
Personally, I suspect there may be a problem with TM1.1 Signal.
What do you guys think?
What should I do in this case?
Thanks in advance.