Hi Kang,
You mentioned the starting point of waveform not matching to ending point. Do you mean the numerical value of 1st sample (I & Q) and 7680th sample (I&Q) should be same? if this is what you meant then we have different values. Purna has shared one LTE file with us and in that file also these start and end values do not match.
If my understanding is incorrect, please correct me. If you could share some App note on coherency of DAC it shall help us to understand in more better way. You can share the signal file with us.
Requesting you to please share DAC test file for LTE, we need 1ms of data at 7.68MSPS (7680 I & 7680 Q samples)
Thanks & Regards,
Prasad