In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7V. The thermal voltage V_t = kT/q = 25mV. The small signal input v_i = V_P cos ($$\omega t$$) where V_P = 100mV. The ac output voltage v_ac is

In the circuit shown below, capacitors C₁ and C₂ are very large and are shorts at the input frequency. V_i is a small signal input. The gain magnitude $$\left|\frac{{\mathrm V}_0}{{\mathrm V}_\mathrm i}\right|$$ at 10 Mrad/s 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

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