🔍 Key Concepts

• Common base vs. common emitter vs. common collector characteristics • Relationship between current gain (α, β), voltage gain, and power gain in transistor amplifiers • Typical input impedance values for each configuration

💭 Think About

• Think about which configuration is usually used for high input impedance and which is used for impedance matching to low input sources. • Recall how current gain in a common base stage compares to the transistor’s α and β values, and how that stacks up against the common emitter. • Consider which configuration has very little current gain but large voltage gain, and what that implies about its power gain relative to the others.

✅ Before You Answer

• Verify which configuration (common base, emitter, or collector) is known for very low input impedance. • Check which configuration is typically used when you want high current gain (think β). • Confirm which configuration is commonly used as a voltage follower and what that implies about its voltage gain compared to the others.