I require a 65 MHz output from AD9914 using input frequency of 10 MHz from a signal generator with PLL enabled and the multiplier set to 240.
My problem is the that DDS does not output the desired frequency. It gives me around 60 MHz with side lobes!!!
Also if i change the set output frequency slightly then the lobes keep reappearing at certain frequency.
[But if i disable PLL and provide DDS with an external frequency (high enough about 1GHz) then this problem dont appear and i get a good time domain signal and frequency domain response even for a frequency sweep around 65 MHz]
Am I missing something in the multiplier/PLL setting?
Should there be any hardware changes on the evaluation board to use the multiplier?