Question

Figure shows the transfer characteristics of a base biased CE transistor. Which of the following statements are true?

At V_i = 0.4 V, transistor is in active state.

At V_i = 1 V, it can be used as an amplifier.

At V_i = 0.5 V, it can be used as a switch turned off.

At V_i = 2.5 V, it can be used as a switch turned on.

Options

• a and c

• a, c and d

• b and c

• b, c and d

Answer 1

b, c and d

Explanation:

According to the above graph transfer characteristics of a base biased common emitter transistor, we note that.

1. When V_i= 0.4 V, the output voltage remain same and there is no collection current. So, the transistor circuit is not in an active state.
2. When V_i = 1 V (This is in between 0.6 V to 2 V), the transistor circuit is in an active state and when input is increasing output is decreasing because when CE is used as an amplifier input and output voltages are 180° out of phase. Then it is used as an amplifier.
3. When V_i = 0.5 V, there is no collector current. The transistor is in a cut-off state. The transistor circuit can be used as a switch to be turned off.
4. When V_i = 2.5 V, the collector current becomes maximum and the transistor is in a saturation state and can be used as a switch turned on state.