[SI-LIST] PLL spectrum...

  • From: Tim Lu <timoceous@xxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Fri, 28 Mar 2003 21:49:38 -0800 (PST)

Hi all,

   I am analyzing the output spectrum of a PLL +
Serializer chip. Looking at the serial clock output I
did see the locked output spectrum at 100Mhz.  Second
harmonic at 50Mhz and third harmonic 25Mhz.  

   I do have a total of divided by 4 in the feedback
path.  In the other path the VCO output of 100Mhz are
feed into a serializer block. Where is it also divided
by 4 to get the low speed 25Mb/s parallel data to be
serialized to the 100Mbs.  Both the data and clock
comes out and the spectrum frequency I have mentioned
above are looking at the serial clock from the
serializer.

   Here is my question, is there a way to find out
where the 2nd and 3rd harmonic is coming from?  Is it
coming from the PLL feedback path or is it coming from
the serializr divider?  I can't use the spectrum
analyzer to look at the  inside the chip.  I would
like to find out a way to test and find out where the
2nd and 3rd harmonic is coming from in the chip.  Any
help is greatly  appreciated.

T.

__________________________________________________
Do you Yahoo!?
Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!
http://platinum.yahoo.com
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:     
                //www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: