4.2 Single Stage Bipolar Junction Transistor (BJT) Amplifier

• Meaning of amplification and the need for amplifiers in analogue electronic systems
• Construction, terminals and symbols of an NPN and a PNP bipolar junction transistor
• Forward and reverse biasing of the base-emitter and collector-base junctions
• Transistor currents and current gains: emitter, base and collector currents, alpha and beta
• Comparison of the common emitter, common collector and common base configurations
• Operation of a single stage common emitter amplifier
• Operation of the common collector (emitter follower) amplifier
• Operation of the common base amplifier
• Collector characteristic curves of a transistor
• The d.c. load line and the quiescent (Q) point of an amplifier
• Biasing methods used in a single stage amplifier
• Coupling and decoupling capacitors in an amplifier stage
• Voltage gain, current gain, power gain and gain in decibels
• Frequency response and bandwidth of a single stage amplifier
• Assembling and testing a single stage amplifier on a breadboard
• Testing and troubleshooting a single stage amplifier
• Applications of single stage BJT amplifiers in day to day life

• describe the operation of a single stage transistor amplifier used in analogue electronic circuits
• construct single stage amplifier circuits using schematic circuit diagrams
• analyse a common emitter single stage transistor amplifier in an analogue electronic circuit
• troubleshoot a single stage transistor amplifier in an analogue electronic circuit
• appreciate the importance of single stage amplifier circuits in day-to-day life

“How does a BJT amplifier work?”

“How is a single stage BJT amplifier constructed and tested?”

The titles are open to everyone. Reading a lesson needs an account — sign in or create one.

1. Introduction to amplifiers and the BJT
   40 min · 1 practice tasks · quiz
   Explain what an amplifier does and introduce the bipolar junction transistor.
2. Construction and terminals of the BJT
   40 min · 1 practice tasks · quiz
   Describe the three layer construction and the terminals of NPN and PNP transistors.
3. Forward and reverse biasing the BJT
   40 min · 1 practice tasks · quiz
   Explain the bias conditions that make a transistor amplify.
4. Transistor currents and current gain
   40 min · 1 practice tasks · quiz
   Relate the transistor currents and calculate alpha and beta.
5. Common emitter, common collector and common base
   40 min · 1 practice tasks · quiz
   Compare the three ways of connecting a transistor as an amplifier.
6. The single stage common emitter amplifier
   40 min · 1 practice tasks · quiz
   Describe and analyse a single stage common emitter amplifier.
7. The common collector (emitter follower) amplifier
   40 min · 1 practice tasks · quiz
   Describe the common collector amplifier and its use as a buffer.
8. The common base amplifier
   40 min · 1 practice tasks · quiz
   Describe the common base amplifier and compare it with the other configurations.
9. Collector characteristic curves
   40 min · 1 practice tasks · quiz
   Draw and interpret the collector characteristic curves of a transistor.
10. The DC load line and the Q point
    40 min · 1 practice tasks · quiz
    Draw the d.c. load line and locate the quiescent point of an amplifier.
11. Biasing methods for a single stage amplifier
    40 min · 1 practice tasks · quiz
    Describe common biasing circuits and why stable bias matters.
12. Coupling and decoupling capacitors
    40 min · 1 practice tasks · quiz
    Explain the job of the capacitors in a single stage amplifier.
13. Voltage gain of a single stage amplifier
    40 min · 1 practice tasks · quiz
    Calculate the voltage gain of a single stage amplifier.
14. Current gain, power gain and decibels
    40 min · 1 practice tasks · quiz
    Calculate current gain, power gain and gain in decibels.
15. Frequency response and bandwidth
    40 min · 1 practice tasks · quiz
    Describe how the gain of an amplifier changes with frequency.
16. Building a single stage amplifier on a breadboard
    40 min · 1 practice tasks · quiz
    Assemble and test a single stage amplifier on a breadboard.
17. Testing and troubleshooting a single stage amplifier
    40 min · 1 practice tasks · quiz
    Use instruments to find and correct faults in a single stage amplifier.
18. Applications of single stage BJT amplifiers
    40 min · 1 practice tasks · quiz
    Describe the use of single stage BJT amplifiers in day to day life.