AnsweredAssumed Answered

Frequency ppm of AD9548 distribution clock  is lager but stabled

Question asked by Guan on Jun 4, 2014
Latest reply on Jun 12, 2014 by pkern



I have configured clock in sequence,


1.Write R0x0000-R0x0417 per the setup file

2.Write R0x0A01=0x20; Set user freerun mode

3.Write R0x0005=0x01

4.Write R0x0A02=0x03(from 0x01 to 0x03)

5.Write R0x0005=0x01

6.Read R0x0D01.

I read 0x11, then next sequence.


7.Write R0x0500-0x7FF per the setup file

8.Write R0x0005=0x01

9.Write R0x0A01-R0x0A10 per the setup file

10.Write R0x0005=0x01

11.write R0x0A02=0x00,

12. write R0x005=0x01.

13.Check valid bit in 0x0D0C(bit3), because I use GPS receiver of 10M to REFB.

R0x0D0C = 0x80

Then distribution clock ouput stable. I have uploaded stp to attached file.


Now, I used this clock to supply RRU(antenna of mobile base station), I found RF frequency ppm(not stablity problem) is lager than normal(normal is ppb level, but now I have ppm level), in normal condition, it's decided by clock for RF side.

So whether I have any configurations to fix ppm problem?


Best regards.