How to resolve this problem about the phase error?

The phase error at the begining of burst is very bad (=15 degree) when watched on the CMU200 , while the remaining is almost at 8 degree. My
phone is at the DCS1800 and PCS1900 band . How to reslove this phase error at the begining of a burst from the circuit or software ?

I experience a similar problem. In the beginning of the burst, there is high peak phase error, and later on it comes back to much lower value.

Did you find out the root-cause, wondering?

hilbert

I don't know you circuit/project, however I think:

1) if you have switched frequency synthesizers you should have a look at their time/phase behaviour during the transient
2) check the ramp-up of the PA during RX --> TX phase