                            Amplifier Teaching Aid (GTZ, DED; 86 pages)  Preface  Introduction  Lesson 1 - Semiconductor Review  Lesson 2 - Bipolar Transistor  Bipolar Transistor II  First Evaluation  Lesson 4 - Transistor Fundamentals  Lesson 5 - Transistor Biasing  Lesson 6 - Transistor Biasing II   Lesson Plan    Transistor biasing II    VDB analysis   Worksheet No. 6  Second Evaluation  Lesson 7 - Small Signal Amplifier  Lesson 8 - Small Signal Amplifier II  Lesson 9 - Small Signal Amplifier III  Lesson 10 - Large Signal Amplifier  Third Evaluation

#### Transistor biasing II

Voltage Divider Bias

The most famous circuit based on -the prototype of emitter bias is called the voltage divider bias (VDB).

Recall the steps of analyzing the emitter bias circuit:

1. VE
2. IE
3. IC
4. Voltage drop across RC
5. VC
6. VCE[SFARSIT]

The three most important steps are:

[inceput284]1. IE
2. VC
3. VCE Fig. 6-1: Emitter biased circuit

Problem: Sometimes the voltage from the VCC power supply is too large to apply directly at the base.

Solution:

- extra power supply for the base
- or ==> VDB Fig. 6-2: VDB circuit

The voltage drop across R2 is applied directly to the base, which means:

V2 = VB
1. step: find voltage drop across R2
2. step: subtract 0.7V to get VE   