Understanding two Multivibrator models

[Alex_Bam]

Hello ,
I simulated the two multivibrator models in CMOS technology using the cadence tool. I was expecting the model 2 with Schmitt trigger(ST) will show robustness in PVT (Process Voltage temperature) analysis as compared to model 1 due to ST. But this was not the case both the Models shows the same response to PVT variation analysis means their outputs were stable under varying PVT conditions. Could anyone address my query:

1. Is Schmitt trigger in Model 2 having an edge over model 1?
   Thanks.

 

[Kabelsalat]

Without having used Cadence, I'll suggest your model2 because I believe the separate loop C1-R1-NOT are unstable and will have a tendency to oscillate with high frequency.