Previous GATE Questions on BJT Biasing, Q-point and Finding the operating region of Transistor

The voltage gain Av of the circuit shown below is

(a) 200       (b)   100           (c)    20       (d)    10

Solution :

For a BJT, the common base current gain α = 0.98 and the collector base junction reverse bias saturation current Ico = 0.6 µA. This BJT is connected in the common emitter mode and operated in the active region with a base drive current IB = 20 µA. The collector current IC for this mode of operation is

     a.       0.98 mA

     b.      0.99 mA

     c.       1.0 mA

     d.      1.01 mA

For the BJT, Q1  in the circuit shown has β=∞, VBEon = 0.7 volts, VCEsat = 0.7 volts. The switch is initially closed. At time t=0, the switch is opened. The time t at which Q1 leaves the active region is

     a.       10 ms

     b.      25 ms

     c.       50ms

     d.      100 ms