Question

A common emitter amplifier circuit built using an n-p-n transistor is shown in the figure. Its DC current gain is 300, R_C = 4 kΩ and V_CC = 20 V. What is the minimum base current for V_CE to reach saturation?

 

पर्याय

• 40 μA

• 26.66 μA

• 16.66 μA

• 10 μA

Answer 1

16.66 μA

Explanation:

For CE n-p-n transistor, DC current gain,

`B_"DC" = l_C/l_B`

At saturation state, V_CE becomes zero,

V_CC - l_CR_C = 0

`l_C ≈ V_"CC"/R_"C" = 20/4000 = 1/200` A

Hence, saturation base current,

`l_B = l_C/beta_"DC" = 1/(200 xx 300) = 1/60000` A = 16.66 μA