$3.$ In the circuit shown below, assume for simplicity that all NMOS transistors have the same transconductance, $\backslash ($ g$\_\{$m N$\}\backslash ),$ and the same output resistance, $\backslash ($ r$\_\{$O N$\}\backslash ).$ Similarly, assume $\backslash ($ g$\_\{$m P$\}\backslash )$ and $\backslash ($ r$\_\{$O P$\}\backslash )$ for both PMOS devices. Neglect body effect.

$($a$)$ Compute the output resistance.

$($b$)$ Compute the circuit's transconductance, $\backslash ($ G$\_\{$m$\}\backslash ).$

$($c$)$ Determine the minimum allowable output voltage. $($The transistors must not enter the triode region.$)($We typically choose overdrive voltages to be less than the threshold voltage.$)$