Week 09
Emitter Followers and Buffers
I organize a study path from diodes to single-transistor amplifiers in the order that makes the circuit behavior easiest to revisit.
What I connect in this unit
An emitter follower tracks the base voltage one junction drop lower, giving voltage gain near unity. Its high input resistance and low output resistance reduce loading on the source and improve impedance matching to the next stage.
Concept map
- Voltage following
- High input resistance
- Low output resistance
- Impedance matching
Technical anchor
For small signals, Av ≈ RE/(RE + re) with re ≈ VT/IE, so gain approaches one when RE is much larger than re.
How I review it
Include source and load resistances when calculating voltage transfer before and after the buffer, and also check peak transistor current and output-swing limits.
Connection to the full course
Unit 9 of 12. Unit numbers form a concept-study sequence and do not claim the original class schedule.