Can AD converter AD9122 generate single test tone with the internal NCO?

Question

Hi, 
 Can AD9122 + ADL5375 generate single test tone with the internal NCO of DAC and how to configure the relevant register ? 
 That is to say using AD9122 generate the single tone without the data from fpga(D0 to D16). 
 Thank you !

JMMina · Accepted Answer

Hi tony_tao , 
 Apologies for the delayed response. I tried the experiment again on another AD9122 evaluation board. Although I'm able to generate an NCO output again using the same procedure as in the first board, the amplitude of the tone was arbitrary whenever I either reset the AD9516 chip (Clock distribution) or perform a power cycle (i.e. turned off the power supply then turned on again). There were even instances where there was no output. 
 The amplitude of the single tone was being random depending on the power-on values in the FIFO. Since there is no FPGA board connected, there should be no DCI detected by the AD9122 chip (although in some instances there is which is weird). There are FIFO warning fields in Register 0x18 [7:6] and the FIFO level is indicated in Register 0x19. The value in these fields were not constant during my testing thus the random amplitude levels in the NCO output. 
 Due to this, the answer to your question is no. You can't output a single test tone with the internal NCO only. However, there should be a workaround to this: If you could tie the input data bus to a fixed DC value and find a way to toggle DCI several times so the value gets loaded into the FIFO, this would ensure repeatability that there is always an NCO output and the amplitude will always be the same. 
 Best regards, Marco)

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Can AD converter AD9122 generate single test tone with the internal NCO?