What contributes to the noise floor of a DAC output? How do I interpret the often-seen NSD plots in a DAC product datasheet?
There are three main contributors in the DAC output noise.
1. Quantization noise.
2. DAC Clock wideband noise.
3. Noise from the current source array.
Typically, at low output frequencies the current source noise tends to dominates the DAC output noise performance while the noise contributed by the clock jitter increases with the output frequency. The Noise Spectral Density (NSD) curves in a DAC datasheet shows the noise performance over the output frequency. Not surprisingly, the NSD degrades with the increase of the output frequency. Using a low jitter clock source as the DAC clock helps improve the NSD, especially at high output frequencies. However, there is a limit to which the NSD can be improved, which is determined by the inherent noise from the DAC current array and the quantization noise.
Retrieving data ...