Consider common$-$source circuit$-$configuration, as shown below. A constant current source $(I=500A)$ has been used for biasing this amplifier, which drives a load resistance of $R_L=10k.$ Assume the value of $V_{TH}=0\mathrm{.}9V,$ drain voltage $(V_D)=2V,R_{\text{s}\text{i}\text{g}}=100k,r_g=100k,{}_n*C_{ox}(\frac{W}{L}{)}_n=1m\frac{A}{V^2}$ and the coupling capacitances $(C_{Cl}$&$C_C)$ provide infinite impendence to the DC components of signal.

a$.$ Determine the magnitude of $A_v$ if the value of resistance across gate and drain $(R_{Rd})$ is $10M,$ as shown in the figure above.

$(5$ marks $\}$

b$.$ Using the same value of $R_{gd}=10M,$ determine the new value of $V_D$ and gain $A_v$ on replacing the current source with $I=2mA.$

$(5$ marks$)$i