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Queries about AD6655

Question asked by WayneQ on Dec 9, 2013
Latest reply on Jan 20, 2014 by J.Harris

hi, there

 

i am trying with AD6655 FFT. the testing is as below.

NCO HB↓2 FIR fADC/8 NCO with real output.

the sampling clock is 122.88MHz, FIN=152.824MHz, NCO=153.624MHz

the signal is 14.56MHz; while there is a spur at 16.113MHz.

it seems that 152.824-153.624=-0.8MHz,fADC/8=15.36MHz,then -0.8+15.36=14.56MHz

16.113MHz ( about 16.16MHz ) is generated by fADC/8 NCO.

-0.8+15.36=14.56MHz, which is signal. the other is that -0.8-15.36=-16.16MHz.AD6655_1.jpg

AD6655_2.jpgAD6655_3.jpg

i am not sure whether it is right or not.

 

thanks!

 

Br,

Wayne

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