The voltage gain A_v of the circuit shown below is

For the BJT Q₁ in the circuit shown below, $$\beta = \infty ,\,\,\,\,{V_{BEon\,}}\, = \,0.7V,\,\,\,{V_{CEsat}}\, = \,0.7V.$$. The switch is initially closed. at time t = 0, the switch is opened. The time t at which q₁ leaves the active region is

For a BJT, the common-base current gain $$\alpha = \,\,0.98$$ and the colector base junction reverse bias saturation current I_co = 0.6 $$\mu {\rm A}$$. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20$$\mu {\rm A}$$. The collector current I_c for this mode of operation is

A small signal source V_i(t) = A cos 20t + B sin 10⁶ t, is applied to a transistor Amplifier as shown in fig. The transistor has $$\beta $$ = 150 and h_ie = 3k$$\Omega $$ , which expression best approximates $${V_0}\left( t \right)$$ ?