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AD9834 Harmonic Distortion

Question asked by zaid on Sep 29, 2015
Latest reply on Oct 15, 2015 by mcee



I am using AD9834 as a sine wave source at 25 MHz, I have the evaluation board rev. A. I looked at the output signal without buffering, after the buffer and after the 7th order elliptic filter (I examined these at a lower frequency because the cutoff frequency of the filter is 18 MHz). Beyond 12 MHz all outputs appear distorted on the oscilloscope, but when I use the bandwidth limiting feature they are smoothed out. My application requires driving a resistive  load around 100 Ohms, I would also like to do a frequency sweep with a maximum frequency of 25 MHz. My questions are: If I consider a buffering circuit used on the evaluation board will it perform well with a 3.3 V supply? do you have any good recommendations for a filter that will yield similar performance to the bandwidth limiting feature on the oscilloscope? finally are there any wideband instrumentation amplifiers manufactured by analog devices that can be used to monitor the voltage across the load? Preference is for the least power consuming products.


Appreciate your help.