In transistor circuits, the three basic transistor configurations are:
- Common Base (CB)
- Common Emitter (CE)
- Common Collector (CC)
These configurations are very important for SSC JE, RRB JE, GATE, DRDO, ISRO, UPPCL JE, and other electrical/electronics competitive exams.
Comparison of CB, CE, and CC Configuration
| Parameter | CB Configuration | CE Configuration | CC Configuration |
|---|---|---|---|
| Full Form | Common Base | Common Emitter | Common Collector |
| Input Terminal | Emitter | Base | Base |
| Output Terminal | Collector | Collector | Emitter |
| Common Terminal | Base | Emitter | Collector |
| Input Resistance | Low | Medium | High |
| Output Resistance | High | High | Low |
| Current Gain | Less than 1 | High | High |
| Voltage Gain | High | High | Less than 1 |
| Power Gain | Low to Medium | Very High | Medium |
| Phase Difference | 0° | 180° | 0° |
| Frequency Response | Very Good | Good | Good |
| Main Application | High-frequency amplifier | Voltage and power amplifier | Impedance matching |
| Stability | High | Medium | High |
| Signal Amplification | Voltage only | Voltage and current | Current only |
Common Base (CB) Configuration
Features of CB Configuration
- Current gain is less than 1
- Voltage gain is high
- No phase reversal
- Used for high-frequency applications
- Low input impedance
Applications of CB Configuration
- RF amplifiers
- High-frequency circuits
- Impedance matching in some circuits
Common Emitter (CE) Configuration
Features of CE Configuration
- High current gain
- High voltage gain
- High power gain
- 180° phase shift between input and output
- Most widely used transistor configuration
Applications of CE Configuration
- Audio amplifiers
- Voltage amplifiers
- Power amplifiers
- General-purpose transistor circuits
Common Collector (CC) Configuration
Features of CC Configuration
- Also called Emitter Follower
- High current gain
- Voltage gain nearly equal to 1
- No phase reversal
- Very high input impedance
- Low output impedance
Applications of CC Configuration
- Impedance matching
- Buffer amplifier
- Signal isolation
Important Exam-Oriented Points
- CE configuration is the most widely used transistor configuration.
- CB configuration is mainly used for high-frequency applications.
- CC configuration is mainly used for impedance matching.
- CE configuration provides highest power gain.
- CC configuration is also called emitter follower.
- CB and CC configurations have no phase reversal.
- CE configuration has 180° phase reversal.
Quick Revision Table
| Configuration | Current Gain | Voltage Gain | Phase Shift | Main Use |
|---|---|---|---|---|
| CB | Low | High | 0° | High Frequency |
| CE | High | High | 180° | Amplifier |
| CC | High | ≈ 1 | 0° | Impedance Matching |
Conclusion
CB, CE, and CC are the three basic transistor configurations used in electronic circuits. Each configuration has different characteristics related to gain, impedance, phase shift, and applications.
Among them, CE configuration is the most commonly used because it provides high voltage gain, current gain, and power gain.