$10\mathrm{.}55$ Consider an ideal n$-$channel MOSFET with a width$-$to$-$length ratio of $($WL$)10,$

an electron mobility of n $400$ cm$2/$V$-$s$,$ an oxide thickness of tox $475,$ and

a threshold voltage of VT $0\mathrm{.}65$ V$.($a$)$ Determine the maximum value of source

resistance so that the saturation transconductance gms is reduced by no more than

$20$ percent from its ideal value when VGS $5$ V$.($b$)$ Using the value of rs calculated

in part $($a$),$ how much is gms reduced from its ideal value when VGS $3$ V$?$