Common Emitter Amplifier

• amplifier based on Bipolar Junction Transistor with the common emitter configuration
• in active working region

Diagrams §

Amplication:

Input and Output §

• input characteristics: $V_{be},I_b$
• output characteristics; $V_{ce},I_c$

Biasing the Transistor §

• biasing: running DC current through the 3 terminals of a transistor to set its region of operation and operating point or q-point
• $V_{cc}$ flows to $R_1$
• $R_1$ and $R_2$ acts as a voltage divider
• $V_b=V_{cc}\frac{R_2}{R_1+R_2}$

Beta §

• $V_c\propto V_{cc}\propto V_b⟹I_b=\beta I_c$
• $\beta =\text{hfe}$ on transistor label

Demonstration §

Given $R_L=1.2k\Omega$ and $V_{cc}=12\text{V}$