DS588 Datasheet, PDF (9/24 Pages) Xilinx, Inc – Programmable interrupt generation

X-Ref Target - Figure 6
XPS Delta-Sigma Digital to Analog Converter (DAC) (v1.01a)
DS588_06_100909
Figure 6: Filter Cutoff Frequency as a Function of RC
To resolve each DACin sample to the full precision of a Delta-Sigma DAC, the sample rate, i.e., the rate
that DACin changes, must be less than or equal to 1/(2^{(C_NUM_DAC_BITS)}) of the CLK frequency. In
some applications, such as a programmable voltage source, this is not an issue.
As DAC width and the desired sample frequency increases, it may not be possible to meet the above
criterion. In practice, the sample rate sometimes exceeds 1/(2^{(C_NUM_DAC_BITS)}) of the CLK frequency.
Though this compromises precision at higher frequencies, it is often possible to get satisfactory results.
For example, the16-bit audio DACs in a CD system would require a clock frequency of 2.9 GHz for full
resolution of the highest frequencies. In practice, a much lower clock frequency is used. One reason this
is acceptable is because the sensitivity of the human ear to noise becomes lower as the frequency
increases.
DS588 December 2, 2009
www.xilinx.com
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Product Specification