Question

Draw a neat circuit diagram to study C-E transistor characteristic. Explain the input and output characteristics.

Answer 1

C-E stands for common emitter transistor characteristics and are graph between voltages and current for a transistor when emitter is common terminal and is grounded so base is input and collector is output terminal.

1) INPUT CHARACTERISTIC:--

i)Variation of base current with base emitter voltage at constant collector emitter voltage is called input characteristic of transistor.

ii)Base emitter voltage is less than barrier voltage and base current is small in case of forward biased diode.

iii)Base emitter voltage exceeds barrier voltage base current increases sharply with small increase in voltage of base emitter.

iv)The value of base current is smaller than that in normal diode, more than 95%majority emitter carriers go to collector to constitute collector current.

2) OUTPUT CHARACTERISTIC:--

i)Variation of collector current with collector emitter voltage at constant base current is called output characteristics of transistor.

ii)When voltage across collector and emitter increase from 0 to about 0.5 V the collector current increases rapidly.

iii)Once collector emitter voltage exceeds voltage of base emitter the output current of collector varies very slowly but linearly with common emitter voltage.

iv)Larger the value of base current larger is the value of collector current for given voltage of common emitter.

Answer 2

Input/output characteristics

Explanation:

Input Characteristics:

Variation of base current with base emitter voltage at constant collector emitter voltage is called input characteristic of transistor.

1. In case of forward biased diode, the base emitter voltage is less than barrier voltage and the base current is small.
2. Base emitter voltage exceeds barrier voltage and base current increases sharply with small increase in voltage of base emitter.
3. Base current is smaller than at normal diode. More than 95% majority emitter carriers go to collector to constitute collector current.

Output Characteristics:

Variation of collector current with collector emitter voltage at constant base current is called output characteristics of transistor.

1. When voltage across collector and emitter increase from 0 to about 0.5 V,  the collector current increases rapidly.
2. Once collector emitter voltage exceeds voltage of base emitter, the output current of collector varies very slowly but linearly with common emitter voltage.
3. Base current value is proportional to the value of collector current for a given voltage of common emitter.