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AD5791 Broadband Noise?

Question asked by Driz on Apr 18, 2017
Latest reply on Apr 18, 2017 by msamera

1.) What is the broadband self-noise of the AD5781? Specifically, a single RMS measurement taken with an "audio" bandwidth of 20Hz - 20kHz, without weighting factor, at room temperature, etc. I'm confused because this part has a voltage output of 20Vpp, which means that its lowest ("bit 1 active") output would be -77dBu (110uVrms), which is probably 2 orders of magnitude higher than the self-noise of the DAC. Given that the DAC's stated resistance is 3k4 ohms, I assume this resistance (thermal noise) would represent the bulk of the DAC self-noise. That is, 3k4 ohms exhibits a thermal noise of around 1uVrms, or -117dBu, measured with an audio bandwidth of 20Hz-20kHz, unweighted. Is this a correct assumption? 

 

2.) What is the maximum clocking rate for the AD5781 (maximum PCM input sample rate)?  1 Mhz?

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