> Do op-amps have a limit on the amount they can amplify a signal ?

Yup.  This will be in the spec sheet.

> What I am
> finding is that if you increase the difference in resistance in the
divider
> in a differential amplification setup, at a certain point, the signal
> becomes non-linear at the peaks.  Increasing the reference voltage into
the
> op-amp does not seem to help.  At a certain point in the divider value,
the
> output simply shifts further up from zero, rather than increasing the
gain,
> and the peaks are flattened out.

This sounds more like you are hitting other limits than gain.  Opamps also
have finite input impedence and non-zero bias and offset currents.  These
all cause increasing trouble as the impedence driving the inputs
increases.  You should post your exact circuit.


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