Elan Digital Systems Ltd.
7
AD125 USER’S GUIDE
that the noise is Gaussian in distribution and is subject to the usual
statistical spread in its peaks and troughs from moment to moment.
So the converter output looks noisy, or at least more noisy than you
might expect. Normally this is not a problem but occasionally some
kind of post-processing of the data samples will be required in
software. This may mean a simple averaging process over say 10 or
more samples, or could be a properly designed digital filter. This
will depend on the exact application. Bear in mind that this
averaging could reduce the bandwidth of the data you are acquiring
and will increase the settling time needed for step-input changes.
The AD125 inevitably introduces several extra sources of noise:
•
The voltage references
•
The internal power rails
•
Ground noise
•
Noise from the front-end analogue circuits.
The power rails used inside the AD125 are designed to help
minimise power rail feedthrough.
All of these noise sources will act to degrade the ENOB attainable.
Post processing the data using a digital filter will help to improve the
effective resolution by reducing random noise.
