AD9208: Harmonic of Decimated FS mixes with NCO

Discussion created by Dwijen.Pandya on Dec 19, 2017
Latest reply on Jan 11, 2018 by Dwijen.Pandya


I am using AD9208 for one of my application. I am using AD9208-3000EBZ+ADS7-V2EBZ for the evaluation

In my setup Fs is 3GHz

Decimation Rate is 8

Decimated Fout (Decimated Fs) is 375MHz (3GHz/8)

NCO is 702MHz

RF In to the ADC is 800MHz

I have observed that there is spur in the output spectrum that is arising from mixing of the harmonic of Fout with NCO.

For the above setup there is spur at 48MHz.

2*375MHz - 702MHz = 48MHz


The snapshot of the ACE setup and the output spectrum is attached.

Is this spur expected? What can be done to minimize this spur?