Difference Between BJT Configurations

Compare Common Emitter, Common Collector and Common Base Configuration

The article is about all three BJT configurations and their characteristics. You can compare input dynamic resistance Ri, output dynamic resistance RO, current amplification factor Ai, voltage gain AV, power gain AP for different transistor configuration.

Each configuration has its characteristics and area of applications. 

Let's get started. 

Characteristics	Common Emitter	Common Collector	Common Base
Common Terminal	Emitter	Collector	Base
Input Current	IB	IB	IE
Input Voltage	VBE	VBC	VEB
Input Terminal	Base	Base	Emitter
Output Current	IC	IE	IC
Output Voltage	VCE	VEC	VCB
Output Terminal	Collector	Emitter	Collector
Input Dynamic Resistance Ri	High 500 - 5KΩ	Highest 150 - 600KΩ	Low 50 - 500Ω
Output Dynamic Resistance RO	Low 50-500KΩ	Low  100 - 1000Ω	Highest 1 - 10 MΩ
Current Gain Ai	Beta is about 99 β = IC/IB	High (Beta is about 99)	Alpha is less than unity
Voltage Gain Av	High	Less than or equal to unity	High
Power Gain AP	Highest	Less than or equal to unity	Medium
Phase Shift	180° out of phase	0°	0°
Applications	Audio applications	Impedance matching network	High-frequency applications

I have written comprehensive articles on these configurations.

• Common Collector or Emitter Follower Configuration
• Common Base Configuration
• Common Emitter Configuration