For the common-source transistor $Q_1$ is cascoded as shown, where the dc bias arrangement is not shown.
Assuming $Q_1$ and $Q_2$ are biased so that $g_{m1} = g_{m2} = 2 \text{ mA/V}$, $r_{o1} = r_{o2} = 20 \text{ k}\Omega$, $R_{sig} = R_L = 20 \text{ k}\Omega$ and $C_L = 10 \text{ fF}$,
For the capacitances of $Q_1$ and $Q_2$ to have the same values ($C_{gs} = 40 \text{ fF}$ and $C_{gd} = C_{db} = 10 \text{ fF}$).
What is the value of $R_{out}$ ?
Select one:
A. $R_{out} = 800 \text{ k}\Omega$
B. $R_{out} = 200 \text{ k}\Omega$
C. $R_{out} = 400 \text{ k}\Omega$
D. $R_{out} = 100 \text{ k}\Omega$
