1. EKT104 ANALOG ELECTRONIC CIRCUITS [LITAR ELEKTRONIK ANALOG] BASIC BJT AMPLIFIER (PART III)
DR NIK ADILAH HANIN BINTI ZAHRI

2. COMMON-COLLECTOR AMPLIFIER
SMALL-SIGNAL VOLTAGE GAIN
INPUT AND OUTPUT IMPEDANCES
SMALL-SIGNAL CURRENT GAIN

3. COMMON-COLLECTOR AMPLIFIERvO
Common collector circuit
(Emitter-follower)
Small-signal equivalent circuit (using transconductance parameter)

4. COMMON-COLLECTOR AMPLIFIER - SMALL-SIGNAL ANALYSIS: VOLTAGE GAIN-

5. COMMON-COLLECTOR AMPLIFIER - SMALL-SIGNAL ANALYSIS: VOLTAGE GAIN-
Example 1: Given Rs=0.5kΩ, R1=50kΩ,R2=50kΩ,RE=2kΩ, VCC=5V, β=100, VBE(on)=0.7V and VA=80V. Calculate the small signal voltage gain of the common-collector circuit.

6. COMMON-COLLECTOR AMPLIFIER - SMALL-SIGNAL ANALYSIS: VOLTAGE GAIN-
Example 1: Given Rs=0.5kΩ, R1=50kΩ,R2=50kΩ,RE=2kΩ, VCC=5V, β=100, VBE(on)=0.7V and VA=80V. Calculate the small signal voltage gain of the common-collector circuit. (Ans:ICQ=0.8mA,VCEQ=3.4V ,AV=+0.964)

7. COMMON COLLECTOR AMPLIFIER -Output Impedance(Output Resistance,Ro)-
Test Current
Test Voltage
Small-signal equivalent circuit (using transconductance parameter), assuming source resistance, Rs to be zero
The output impedance analysis on the next slide is based on this circuit.

8. COMMON COLLECTOR AMPLIFIER -Output Impedance(Output Resistance,Ro)-
Vπ=-VX
Let;
Test Voltage
Test Current

9. COMMON COLLECTOR AMPLIFIER -Output Impedance(Output Resistance,Ro)-
Example 2:
Given the following circuit (same as Example 1), calculate the input and output resistance. Assume the transistor & circuit parameter are;β=100, VCC=5V, VBE=0.7V, VA=80V and ro=100kΩ.

10. COMMON COLLECTOR AMPLIFIER -Output Impedance(Output Resistance,Ro)-
Example 2:
Given the following circuit (same as Example 1), calculate the input (Rib & Ri)and output resistance (RO). Assume the transistor & circuit parameter are;β=100, VCC=5V, VBE=0.7V, VA=80V and ro=100kΩ. (Ans:Rib =201.3kΩ ,Ri=22.2kΩ, RO=31.6 Ω)

11. COMMON-COLLECTOR AMPLIFIER - Small-signal Analysis: Current Gain-
where
If R1R2  Rib and ro  RE then
Ai  (1+)

12. COMMON-BASE AMPLIFIER
SMALL-SIGNAL VOLTAGE GAIN
INPUT AND OUTPUT IMPEDANCES
SMALL-SIGNAL CURRENT GAIN

13. COMMON-BASE AMPLIFIER - Circuits-
Common-base circuit
Small-signal equivalent circuit

14. COMMON-BASE AMPLIFIER - Small-signal Analysis: Voltage Gain-
If RS approaches zero, then Av = gm(RC||RL)

15. COMMON-BASE AMPLIFIER - Small-signal Analysis: Current Gain-
If RE approaches infinity and RL approaches zero, then;

16. COMMON-BASE AMPLIFIER - Small-signal Analysis: Input Impedance-
Input resistance Ii Ib
Rie
Input resistance Rie = re =

17. COMMON-BASE AMPLIFIER - Small-signal Analysis: Output Impedance-
Output resistance Ro Ix Vx
Output resistance Ro = RC

18. SUMMARY & COMPARISON Configuration Common Emitter Common Collector
Common Base
Voltage Gain
Av > 1
Av  1
Current Gain
Ai > 1
Ai  1
Input Resistance
Moderate
(kΩ)
High
(50-100kΩ)
Low
(Ω)
Output
Resistance
Moderate to High