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I am using LT1994 Fully Differential Input/Output Amplifier for a single-input to differential output configuration with no problem. I need to use same amplifier for differential input to single-output configuration as tried in LTSpice simulation. This seems to work (attenuates input signal) but draws excessive current for this IC (~86mA). Seems to be a problem.
How can I achieve normal current levels?
Am I doing wrong by trying to get single-point output from a 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 – Schematic created using CircuitLab
The approach is right, but you could also consider a simple differential amplifier like this (taken from Wikiepedia).
It's because you shorted the negative output to ground. If you remove the connection to ground the excessive current will disappear.
If you want to maintain fully differential loading of the outputs connect it to ground with a 3.3K resistor and 220nF capacitor in series (ie. copies of R5 and C2). Simply only having the feedback path through R4 should be fine though.
