Does the ADF5000 show self-oscillation with no RF applied? If yes, how can that be avoided (except power down)?
yes like with most RF dividers, the input stage will self-oscillate with no RF present.
The only way to overcome this is to use the hardware powerdown pin (CE) .
The self-oscillation frequency for the ADF5000 is ~ 10GHz. This halves for
every extra divide-by-2 stage, so 5GHz for ADF5001 and 2.5GHz for ADF5002.
THanks for your comments. Now for dividers with differential inputs, an easy way to avoid the self-oscillation is to DC offset the inputs. WIth the ADF5000 having a single-ended input this will not work.
YOu suggest to use the power-down pin. This iwll work for me if the response time of the pin is in the order of 5 ns or less. Do you have any data on that?