gmcrit

hi,
the typical amplidute of Xtal is about (2I/gmcrit), where I is the bias current, gmcrit is the critical start-up gm.
to the more detail analysis you can refer to vittoz's jssc paper in the yesr 1989.
jeff.yan

It depends on the oscillator topolgy.
If you use CMOS gates, you can get rail to rail swing
when the frequency is not too high.

Most of the bipolar oscillators I have seen run a volt or two p-p. At some point you overdrive the xtal and you get added loop loss and strange modes showing up, so it is not good to overdrive them.

Same with most resonators, like SAWs and YIGs, overdrive them and you get garbage.