Re: CMOS Inverter
I don't think it will oscillate, even in practical mode, because the oscillation frequency it will be so high, but the inverter has 2Cgs which brings two poles at pretty low freq compared with the oscillating freq....
Anyway, if we consider it will start to oscillate (consider Barkhausen conditions true), if the output(or input in this case) will pass throw Vdd/2 (or more precisely Vdd.Rn/(Rp+ Rn) ), the two MOS will be in saturated region, and the current will pass from Vdd to Gnd constantly. There is a possibility that the voltage established on the output to bring one MOS out from saturation (especially when Vdd is very low), but I don't think it will start to oscillate.
The two MOS will always be in saturated region because the Vds = Vgs ( >(Vgs-Vth) in nMOS case), so the two MOSes can be swapped with two current sources(controlled by voltage), but lets not forget that the MOS has Cds,Cdb,Cgs too which are pretty big . But like I said, in static state all is stable, nothing is unstable. The big question that I can think is that if the inverter is not well balanced, but I think it will reach into a stable point anyway.
Please correct me, I'm shore that I've made some mistakes...
Best regards