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ADF4350: no lock

Question asked by andreasz on Jul 13, 2011
Latest reply on Jul 14, 2011 by rbrennan

Hi there,
I'm attempting to use the ADF4350 as a local oscillator in my receiver. Frequency range of the ADF4350 is from 160 MHz to 2 GHz in 1kHz steps. I have designed a 10kHz BW loop filter with ADI Sim (file atached). The problem: I can't achieve a lock. On the CPout-Pin i measured oscillation (scope print atached).

 

I have configured the registers with the following sequence:
Register 5: 00 40 00 05
Register 4: 00 c0 40 2c
Register 3: 00 00 00 03
Register 2: 01 03 5e c2
Register 1: 08 00 83 21
Register 0: 0c 80 00 00

 

The Frequency on the REFin-Pin is 10.4 MHz, I have verified the PFD-Frequency by setting the MUXOUT to R Divider Output, it is 400kHz.

 

How should i configure my circuit to achieve a lock?

 

Thank you for your help!

 

Regards,
Andreas

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