HELP! Swiching mode or linear mode (saturation)?

A Class E power amplifier working at 433MHz I am designing has a class F driver stage. I am pretty sure the transistor in output stage works as a switch (nonlinear, triode and cutoff mode). How about the transistor in the driver stage? Does it work in Saturation mode (linear) or switching mode (cutoff and triode)? Main purpose of the driver stage is to shape the input waveform of sinusoid into square waves. The two LC tanks peak at the fundamental frequency and the third harmonic.