$9\mathrm{.}16$ An NMOS differential amplifier with equal drain resistors, RD $=47$ k$,$ has a differential gain Ad of $20$ V$/$V$.$ What is the value of gm for each of the two transistors? If each of the two transistors is operating at an overdrive voltage VOV $=0\mathrm{.}2$ V$,$ what must the value of I be$?$ For vid $=0,$ what is the dc voltage across each RD$?$ If vid is $20-$mV peak$-$to$-$peak sine wave applied in a balanced manner but superimposed on VCM $=0\mathrm{.}5$ V$,$ what is the peak of the sine$-$wave signal at each drain? What is the lowest value that VDD must have to ensure saturation$-$mode operation for Q$1$ and Q$2$ at all times? Assume Vt $=0\mathrm{.}5$ V$.$