Lab Manual at www.docircuits.com - common Emitter Amplifier : BJT

1. Access this lab-manual at:
http://www.docircuits.com/lab-manual/24/common-emitter-amplifier
Common Emitter Amplifier
Aim
The aim is to
1. Understand the function of a CE Amplifier
2. Construct a CE Amplifier
3. Understand Biasing
4. Perform small signal analysis on CE Amplifiers
Related Experiments
BJT
Description
Theory:
¨This configuration of the transistor is called the “common emitter” configuration.
¨This is because both the signal source and the load share the emitter lead as a common connection point
shown in bold lines in the figure ( ignoring the supply connections ).
¨Current through the meter movement in this circuit will be β times the solar cell current. With a transistor
β of 100, this represents a substantial increase in measurement sensitivity. Note - that the additional power
to move the meter needle comes from the battery on the far right of the circuit, not the solar cell itself. All
the solar cell's current does is control battery current to the meter to provide a greater meter reading than
the solar cell could provide unaided.
Procedure:
¨Use a AC Source as opposed to a constant current source for the Base.
¨Setup the circuit as shown. Use a collector resistance of 8 Ohms
¨Use a function generator instead of DC Source 0 and set it to 1.5 V, 2 KHz.
¨Use a series resistance of 1K Ohms.
Run time domain analysis and see the output waveform by clicking Analyze. Set the analysis time to 2 ms.
Conclusion
We can now see that as the input is biased upwards, the output is realized completely but inverted compared to the
input.
The result is as shown below:
COMMON EMITTER
AMPLIFIER

2. The result is as shown below: