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Dear all Hi;
I've implemented sigma delta ADC on cyclonII DE1 FPGA.
the analog input is digitized at the multi-bit output (some pics attached)
now I want to evaluate the output by measuring the Signal to Noise Ratio (SNR) and ENOB and power spectrum but I dont know how to do that in practice?
using which software or which device ?
and how to get the diagrams for SNR and Power spectrum?
can anybody guide me?
Thank you
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you need first to understand the ADC terms which may vary from vendor to another. Here is a good guide.:
http://www.analog.com/static/imported-files/tutorials/mt-003.pdf You will need to:
pass single tone through ADC.
apply fft offline on captured data (with say hann window to uncover noise floor)
make your compuations. You need to do computations rather than visually assess spectrum.
you need take into account your fft resolution(which adds false 10log(resolution/2) to SNR).
measure SNR as the difference between top of tone and noise floor which should be reasonably flat(exclude harmonics)
The above link defines terms very well.
Honored Contributor
