Q$-1-(30$ Points$)$

Consider the circuit shown below. Use the following parameters for your calculations. Transistor parameters: $h_{FE}==300,|V_{BE}|=0\mathrm{.}6V,V_T=25mV,V_A=$ infinite. AC signal $"V_i"$ is applied at the input.

a$)$ Find $DC$ operating values for $I_{C1},I_{C2},I_{C2}$ and $I_{C4}.$

$I_{C1}=q,I_{C2}=q,I_{C3}=q,I_{C4}=q,$

b$)$ Determine the input resistance, CMRR of the differential amplifier, and the voltage gain $(\frac{V_{E4}}{V_i}).$

$A_v=q,$ CMRR $=q,r_{in}=q,$