What impedance should have an LC filter connected to IOUT pin of AD9834?
I have a low pass chebyshev filter with a cutoff frequency of 32.5 MHz with 50 ohm impedance designed with http://www.wa4dsy.net/filter/hp_lp_filter.html and built with commercial values
Signal without filter is without biasing:
But with filter attached signal is distorting.. In image yellow is signal DDS_OUT and blue is DDS_OUT_FILT
There is a lot of offset, vertical offset of track is shifted to show both tracks.
I attach DDS schematic
I've solved, LC filter impedance must be 200 ohm