I need to create a differential signal using low power single ended op amps(not a fully differential op amp).
Obviously an inverting op amp gets the signal inverted BUT the use of inexact resistors produces a differential error that is not acceptable. I do not have the equipment or quality components to get decent results.
Is there an op amp topology(can use more than one op amp) that can take a signal and produce an inverted signal that is nearly perfect and doesn't dependent on external component values?
For example, a non-inverting buffer is "ideal" as far as I'm concerned. Since there are no external components the gain is exact. Unfortunately the inverting buffer requires resistors which create a variable gain(either due to tolerance, temperature, or whatever).
Basically the circuit topology I'm using is one op amp for gain/drive and another taking it's output to invert the signal. This produces a differential signal but the inverting op amp doesn't produce an "exact" copy which causes problems. (Here the issue, again, comes from the external gain resistors not being exact)
Maybe there is some way to combine the two stages in to one in some ingenious way to get a fully differential output?
Also, the output impedance of the signal to the op amps is a not very high or very low(around 1k-10k) will effect the accuracy of the inverting op amp configuration.
(I'd use a fully diff. op amp if I could find one for my applications... but they don't seem to exist. (low power < 500uA, high voltage(>= 36V)))