Aim: To study the I-V Characteristics of the Common Emitter configuration of BJT

Apparatus:

1. Two voltmeter & two ammeter (mA & µA)
2. Two power sources
3. Connecting wires
5. Transistor BJT547.

Theory:

When the emitter is kept common or grounded between the input and output this mode of the transistor is called C-E configuration

INPUT CIRCUIT

OUTPUT CIRCUIT

In the circuit here emitter –base is kept forward biased with battery VBB  and collector-base is kept reversed biased with the help
Of battery VCC.

OBSERVATION:

Input characteristic:

The graphical relationship between the input voltage and base current (Ib) keeping output voltage (VCC) constant is called input

Characteristics:

At constant output voltage Vcc =2, 4,6v respectively.

This graph depicts that initially, the voltage of battery VBB is smaller, then emitter current remains zero (in the case of Si <0.7)

Base current also remains zero. With an increase in voltage, current increases and at knee voltage (VK) it increases significantly.

OUTPUT CHARACTERISTICS:

It is a relation between output voltage (VCC) and collector current (IC) keeping base current constant (Ib).

At constant base current =50µA, 80µA, 100µA respectively.

This graph depicts that collector current almost remains independent with output voltage VCC.
Input collector current increase only when emitter current (Ie) increases.

RESULT:

I-V characteristics of C-E configuration is studied.

INPUT RESISTANCE:

The ratio of change in input voltage is to base current gives input resistance at a constant output voltage
Ri =ΔVi/ΔIb

OUTPUT RESISTANCE:

The ratio of change in output voltage is to collector current (IC ) at a constant base current Ib
Ro  =ΔVo /ΔIC

PRECAUTIONS:

• All the connection should be tight.
• Reading should be noted without parallax error.
• The applied voltage, the current should not exceed the maximum rating of the given transistor.

MULTISIM:

INPUT CHARACTERISTICS

OUTPUT CHARACTERISTICS