  We numerically simulate the distortion of an analog signal carried in a
microwave photonics link containing a phase sensitive amplifier (PSA), focusing
mainly on amplitude modulation format. The numerical model is validated by
comparison with experimental measurements. By using the well known two-tone
test, we compare the situations in which a standard intensity modulator is used
with the one where a perfectly linear modulator would be employed. We also
investigate the role of gain saturation on the nonlinearity of the PSA.
Finally, we establish the conditions, in which the signal nonlinearity
introduced by the PSA itself can be extremely small.
