1. ● Establish a constant voltage V B. ● Current-derived negative feedback.The degree of success of the negative feedback is Bias Stability. Biasing Circuit

2. cut-off conditions,

3. Example ● A transistor is to be biased at a collector current of 1 mA when a 12-V power supply is applied. Using the above figure, determine the values of R1, R2, and RE if 3.4 V is to be dropped across RE and if the current through R2 is to be 10 IBQ. Assume that for the transistor used, VBEQ = 0.6 V and hFE = 100.

4. Example Also, VB = VRE + VBE = 3.4 + 0.6 = 4 V. VR1 = VCC – VB = 12 – 4 = 8 V

5. Common Emitter Amplifier

7. Transconductance=how much I C changes with a fluctuation in V BE. The terminal voltage gain is therefore In practice, V T = 26 mV at room temperature

8. Model ● Basic Equation ● Equivalent Circuit ● Simulation model