I've been reading up on the concepts of properly isolating sensitive signals in applications like analog front ends.
For small signals, it is appropriate to use an in-amp. I understand that. But what about isolation?
It seems (see figure below) most flow-charts and lectures show the in-amp being the first stage of input, cascading into an isolation amplifier or barrier of some type.
Practically speaking, looking at isolation amplifiers it seems their topology outputs a differential signal to mitigate noise. However, what if you are only interested in observing the positive wave cycle? In this instance is it appropriate to leave the naught output floating? Pull down resistor? Or cascade into a differential amp?
TI Isolation Amp
From this line of thought, why is it important to first feed the signal to an inamp before isolation? If an isolation amp outputs a fully differential signal wouldn't it make sense to first isolate the signal, feeding the differential output to the difference amp and reduce the component count?