spectral purity of a sine generated by a NI 9263 limited by DAC non linearities

[max_tomatis]

Dear all, 

I am generating a sine at 1 kHz (200 mV p-p) from the DAC NI 9263 (through FPGA,  NI 9111 and NI 9012) and I am measuring the spectral purity at the output (see attached figure).

I see that the 2nd and 3rd harmonic are 50 -60 dB lower than the 1st harmonic whereas for my application it should be lower than 70 dB .

The spectral purity of the digital sine sent to the DAC is not the limit since the harmonics are lower than 100 dB .

Does anybody know the non-linearity of the NI 9263 DAC?

Has anybody generated a high spectral purity sine from a NI 9263?

Regards

Max

[Claudio_Guido]

Hi,

Only one question...

How many samples are you generating in one period of a sine?

Could you increase the number of this value and observer the difference in amplitude from the harmonics?

Regards,

Claudio

[max_tomatis]

Hi,

we have 96 points in the sinusoid generated from a Look up Table , and when we calculate the power spectral density the 2nd and 3rd harmonic are very low. We will try with 960 ponts to see the behaviour

Regards

Massimo