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DDS output not sinusoidal

Question asked by t.sawant1069 on Jun 19, 2018
Latest reply on Jun 26, 2018 by mcee

Hi,

 

I am using AD9959 evaluation board to generate my signal. However, the output of the DDS board is not perfectly sinusoidal for frequencies lower than 1/4th the system clock frequency. Is this generic to DDS frequency generators? 

 

Following are the oscilloscope traces. 

The board is being clocked by a 10Mhz signal generator

Yellow->DDS output, Blue->Clock signal

With clock multiplier disabled for an output of 0.5MHz.

With clock multiplier disabled for output 2Mhz.

 

With clock multiplier 10 for output 2 Mhz

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