A small signal source, $V_i(t)=A \cos \left(10^5 t\right)+B \sin \left(10^7 t\right)$ is applied to a BJT circuit as shown in the Figure.

Assume zero source resistance, $V_{B E}=0.7 \mathrm{~V}, \beta_{\mathrm{dc}}=99$, Early voltage $=100 \mathrm{~V}$ and Thermal voltage $=25 \mathrm{mV}$. Effect of internal parasitic capacitances of the BJT may be neglected. Which expression is the best approximation of the output voltage $V_o(t)$ ?

A circuit using an ideal OP-AMP is shown in the Figure.

Which of the following options gives the correct value of the current $I_\chi$ ?

An $n$-channel MOSFET is connected as shown in the Figure.

Assume $\mathrm{V}_{\mathrm{TH}}=1 \mathrm{~V}, V_{D D}=5 \mathrm{~V}$, and $\mu C_{O x}\left(\frac{W}{L}\right)=2 \mathrm{mAV}^{-2}$ and neglect channel length modulation effects.

The gate voltage ( $V_G$ ) of the n-channel MOSFET (in Volt) is $\_\_\_\_$ . (rounded off to two decimal places)

Consider an ideal OP-AMP circuit as shown in the Figure.

The resistances $R_1=R_2=R_3=R_4=50 \mathrm{k} \Omega$.

The magnitude of the closed loop gain is $\_\_\_\_$ . (rounded off to two decimal places)