Differential Input to Single Ended Output with Fully Differential Amplifier?
The testbench for your circuit should have a source that is referenced to ground. Use a single voltage source to generate the input common mode level and two sources for the signal with opposite phase for the input signal. Of course you can have the same functionality with two sources as well, but it makes the schematic easier to read.







simulate this circuit &ndash; Schematic created using CircuitLab

The approach is right, but you could also consider a simple differential amplifier like this (taken from Wikiepedia).