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Home Electrical and Electronics Analog Electronics To Plot and Study the Input and Output Characteristics of BJT in Common Emitter Configuration.
Analog Electronics Lab Experiments

To Plot and Study the Input and Output Characteristics of BJT in Common Emitter Configuration.



Aim

To plot and study the input and output characteristics of BJT in common-emitter configuration.

Apparatus Required:

Transistor Characteristic kit, Multimeter, Connecting leads and Power Supply

Theory:

In common Emitter configuration input is applied between base and emitter while the output is taken across emitter and collector. Thus the emitter forms the terminal common to doth input and output circuits. The load resistance is connected at collector.

Circuit Diagram:

circuit-diagram

Procedure:

  • Connect the circuit as per the circuit diagram.
  • Input charact.

    1. Keep emitter - collector voltage constant.
    2. Vary emitter-base voltage in steps and note down base current reading.
    3. Readings are tabulated and graph is drawn.

    Output charact.

    1. Keep base current constant.
    2. Vary collector-emitter voltage in steps and note down emitter current.
    3. Readings are tabulated and graph is drawn.

    Observation Table:

    S. No Input charact.(Vce=Cons.)/Vbe(Volts)/Ib(mA) Output charact. (Ib = Const.)/Vce(Volts)/Ic(mA)
    1
    2
    3
    4
    5

    Graph:

    input-and-output-characteristics

    Result: The input and output characteristic of transistor in common emitter configuration has been plotted.

    Discussion: With the help of output characteristics we can calculate AC& DC current gain in common emitter configuration.

    Precautions:

    1. Connections should be tight
    2. Handle the equipment's with care

    Quiz:

    Q1:What do you mean by biasing of transistor?

    A1:When dc voltages are applied across the different terminals of transistor, it is called biasing.

    Q2:What is d.c. current gain in common base configuration?

    A2:It is ratio of collector current(Ic) to emitter current (Ie).

    Q3:What is typical value for d.c. current gain ?

    A3:0.99

    Q4:What is a.c. current gain in CB confifuration?

    A4:It is ratio of change in collector current to change in emitter current.

    Q5:What are input characteristics?

    A5:These curves relate i/p current & i/p voltage for a given value of o/p voltage.

    Q6:What are output characteristics?

    A6:These curves relate o/p voltage & o/p current for a given value of input current.

    Q7:Which configuration has highest voltage gain?

    A7:Common Emitter.

    Q8:Which configuration is most widely used?

    A8:Common Emitter.

    Q9:What is operating point?

    A9:The zero signal values of Ic & Vce.

    Q10:Which reigon is heavily doped in Transistot?

    A10:Emitter