BJT

1. EEE3143: Analogue Electronics 1
BJT AMPLIFIER

2. Linear Amplifier

3. AC Load Line

4. Transistor AC Model

5. The Common-Emitter Amplifier

6. The Common-Emitter Amplifier
 Capacitor C2
 The capacitor is used to provide AC grounds for the emitter terminal.
 It will be able to increase voltage gain of the amplifier and also provide high pass filter for
the amplifier
 Resistor RE
 This resistor will make the collector current, IC almost independent from current gain (β)
of the BJT.
 Current gain is varied from one transistor to other transistor across process and
temperature
 This resistor is able to stabilize the DC current even though the current gain (β) is
changing.
 High Impedance for Input and Output
 As the input is voltage, to achieve maximum voltage transfer, the input needs to have high
impedance so that the entire AC signal from the signal source will be transferred to the
input of the amplifier
 The gain of this amplifier depends on the output impedance of the amplifier. Higher output
impedance will produce higher gain for the amplifier

8. Example

10. The Common-Emitter Amplifier

11. The Common-Emitter Amplifier

12. The Common-Collector Amplifier

13. The Common-Collector Amplifier

14. Example

15. The Common-Collector Amplifier

16. The Darlington Pair

17. The Sziklai Pair

18. The CB Amplifier

19. Multistage Amplifier

20. Multistage Amplifier

21. Differential Amplifier

22. Differential Amplifier

23. Advantages and Disadvantages
of Differential Signal compared to Single-ended Signal
 Advantages
 High power supply rejection ratio
 Reject common mode noise
 Disadvantages
 High power consumption
 Matching of transistor is very critical for differential amplifier

24. Quiz