The task is to lock 10MHz OCXO to a standard rubidium using ADF4001. I am using EV-ADF4001SD1Z evaluation broad.
Let me tell the jumper settings on the broad.
LK1 - B
LK2 - B
LK3 - B VDD - 3V
LK4 - A Vvco - 5V
LK5 - A Vp - 5V
Instead of a VCO, an OCXO is used. Initially for the OCXO the supply was from the broad but the voltage dropped less than 3V. So external power supply is used.
A 2nd order passive loop filter was designed using ADIsimPLL. The values of the components are
C1 - 10nF, C2 - 47nF, R1 - 1M. Loop Bandwidth is 9.98Hz and phase margin is 44.5 degrees.
All the required components are placed on the broad.
The settings while designing the loop filter and in Int-N software are Output frequency is 10MHz, phase detector frequency is 25KHz, Reference frequency is 10MHz, Kvco - 6Hz/V, Charge pump current is set to maximum 5mA.
To start with, a signal generator was used instead of rubidium as reference. I have programmed all latches using Int-N software. When I probe on the output of charge pump(CP) , it was observed to be an constant voltage. Even when I change the reference frequency by few Hz, there is no variation at the output of CP. I doubted the SPI communication but it's working fine.
The observation was there is no difference at the output of CP, even if I program or not. The output is constant (I am probing at C1).
Is there any other settings I have do?