Consider a diode biased at $1$ mA$.$ Find the change in current as a result of changing the voltage by $($a$)10$ mV$,($b$)5$ mV$,($c$)+5$ mV$,$ and $($d$)+10$ mV$.$ In each case, do the calculations $($i$)$ using the small$-$signal model and $($ii$)$ using the exponential model. Ans. $($a$)0\mathrm{.}40,0\mathrm{.}33$ mA; $($b$)0\mathrm{.}20,0\mathrm{.}18$ mA; $($c$)+0\mathrm{.}20,+0\mathrm{.}22$ mA; $($d$)+0\mathrm{.}40,+0\mathrm{.}49$ mA