Problem $4.(25$ points$)$ Announcements Consider the following circuit where the Op Amp is ideal unless stated. The parameters of the transistor and the resistor are: k$\text{'}*$ W$/$L $=0\mathrm{.}15*($mA$)/($V $^2)$ VTH $=0\mathrm{.}6$V$,$ lambda $=0$ R$\_\{2\}=30$k$*$Omega and R$\_\{$L$\}=60$k$*$Omega

a$.$ Find the current ID assuming VDD $=5$V b$.$ Find VDs and determine if M$$ is in the active region $[5$ points$]$ Chat C$.$ Find the minimum voltage VDD that keeps M$$ in the active region