$4.$ A ring oscillator was built, using CMOS inverters. The input and output voltages for one of the CMOS inverters were measured, and are displayed below.

$\backslash ($ v$\_\{$n$\}\backslash$Lambda $\backslash )$

$2$

$0$

Determine the following values for the inverter, showing$/$explaining how you determined the values:

a$)$ Rise time and Fall time

b$)$ Propagation Delay

c$)$ Maximum frequency at which the input can switch values