differentialoperational-amplifier
I found this awesome op-amp I can use which is super cheap and super fast (NE592D).
Unfortunately, it has differential inputs and outputs. I can probably deal with the differential inputs, but how can I convert the differential output into a single ended output?
Can I just put one end to ground? or to ground via a DC blocking cap? or even just not connect one side?
AD8521 single ended input: -
It is a true instrumentation amplifier so it will work from a single-ended source as shown above. The circuit also shows how to connect to provide a differential output but this is irrelevant to your question.
does cmrr value make sense for a differential amplifier if its inputs are separate and totally different voltages?
Yes, it makes sense. Consider two independent voltage sources as the inputs to a differential amplifier:
simulate this circuit – Schematic created using CircuitLab
This is equivalent to:
simulate this circuit Where we've defined the differential and common mode voltages to be:
$$V_d = V_{in1} - V_{in2}$$
$$V_{cm} = \dfrac{V_{in1} + V_{in2}}{2}$$
Best Answer
You can just ignore one of the outputs if you only need a single ended output. Leave it open.
It is rather an antique IC, something like 4O years old. What characteristics of the amplifier are so good for your application?
You can't use it as a general purpose amplifier - it's bias current is high; its offset voltage is not very good. You probably won't be able to use feedback without stability issues.
There are probably better ones available now.