Question asked by WN2A on Aug 4, 2011
Latest reply on Aug 5, 2011 by WN2A

Hello,

I am looking at an application at 5850 MHz with a 25 MHz Reference/ 25 MHz Phase Detector frequency. According to ADIsimPLL, one cannot attain the required divide values for this operation. ADIsimPLL comes back with this error message:

Normally this program works very well for most everything I use it for.

Yet in consulting the ADF4107 datasheet, this manual calculation should work:

F vco=[(P x B) +A] x (Fref in/R)

Where F vco= 5850 MHz

P= 8,16,32,64 (prescaler values)

B=3 to 8191

A=0 to 63

R=1 to 8191

I would like to use Fref in= 25 MHz

So for example set P=32, R=1 (so that Fref in= F Phase Detector)   solve for A and B…

5850=[ (32 x B) + A] x (25/1)

then  234=[ (32 x B) + A]

and  choosing largest integer B value:

B=7, and A=10 (legal values of A and B) will satisfy :

5850=[ (32 x 7) + 10] x (25/1)

According to this manual calculation, is it possible to operate the ADF4107 in this manner?

Thanks!

WN2A