$3.$ Use:Vt$=1$V $($Note: Vt is the threshold voltage of the MOSFET.$)$ kn$($W$/$L$)=3$mA$/$V$2$ Vsig is an AC source MOSFET$-1$ has DC values: VGS$=4$V$,$ ID$=13\mathrm{.}5$mA MOSFET$-2$ has DC values: VGS$=5\mathrm{.}3$V$,$ ID$=27\mathrm{.}7$mA $=0($for all transistors$)$ Assume all MOSFETs are biased in saturation region. For the following small$-$signal equivalent circuit, find the following values: $($a$)$ Rin $($b$)$ Rout $($c$)$ Voltage gain: Vo$/$Vsig