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# ADC3583: The noise level of adc3583 issue

The customer would like to know how much Vrms can the noise level of the adc3583 be reached.

Thanks a lot.

Best Regards,

Cherry Zhou

• Hi,

May I know is there any updates?

Thanks!

Best Regards,

Cherry Zhou

• Hi Cherry,

The SNR of the ADC3583 is -85 dBFS. To convert these values to Vrms, we need to understand the fullscale range of the ADC input (3.2 Vpp differential) and LSB size.

VRMS of 3.2 Vpp is 3.2*0.707 = 2.262Vrms.

1 LSB = 2.262 Vrms/ 2^18 = 8.628 uVrms

If we use INL value from the datasheet to help determine average Vrms noise, then +/- 7 LSBs = 14 LSBs...

Vrms_noise = 14 LSBs * 8.628 uVrms = 120.792 uVrms

We can then confirm that this Vrms_noise number matches the -85 dBFS calculation...

dBFS = 20*log(Signal/Noise) = 20*log (2.262Vrms/120.792uVrms) = 85.449 dBFS.

So, we can confidently say that the Vrms_noise is ~120.792 uV.

Best Regards,

Dan