A common-emitter amplifier with an external capacitor C_C connected across the base and the collector of the transistor is shown in Fig.

Transistor data g_m = 5mA/V, $${r_\pi }\, = \,200K\Omega, $$ $${C_\pi }\, = \,1.5$$ pF and $$C\mu \, = \,0.5$$ pF determine the upper cutoff frequency f_H of the amplifier

Match the following.

Group - I

(a)Cascode amplifier
(b)Differential Amplifier
(c)Darlington pair common-collector Amplifier

Group - II

(1)does not provide current gain
(2)is a wide band Amplifier
(3)has very low input impedance Emitter Amplifier and very high current gain
(4)has very high input impedance and very high current gain
(5)Provides high common mode voltage Rejection

A Darlington stage is shown in the figure, if the transconductance of q₁ is g_m1 and q₂ is g_m2, then the overall transconductance
$$g\matrix{ c \cr m \cr } \left[ { \buildrel \Delta \over = {{{i_c}^c} \over {{v_{be}}^c}}} \right]$$ is given by

An npn transistor has a beta cut-off frequency $${f_\beta }$$ of 1MHz and Common Emitter short circuit low frequency current gain $${\beta _o}$$ of 200. The unity gain frequency $${f_T}$$ and the alpha cut-off frequency $${f_\alpha }$$ respectively are