1. Intro to BJT Amplifier Circuits

2. In this Lecture, we will:  Discuss how a BJT is used as a switch (use this as a frame of reference).  Understand the concept of an analog signal and the principle of a linear amplifier.  Learn about small signal models (such as the Hybrid Pi model) for the analysis of BJT linear amplifiers.  Investigate how common-emitter and common-base BJT circuits can amplify a small, time-varying input signal.

3. Voltage Transfer Characteristic for npn Circuit

4. Voltage Transfer Characteristic for pnp Circuit

5. NPN Switch Driving a Load

6. BJT Switches Driving Loads

7. Digital Logic InverterNOR gate

8. Bipolar Inverter as a Linear Amplifier

9. Effect of Improper Biasing on Amplified Signal Waveform (Non-Linear Amplifier)

10. Simple BJT Amplifier Circuit along with DC Model and AC or Small Signal Model

11. I B Versus V BE Characteristic (Determination of r  for small signal model)

12. I C Versus V BE Characteristic (Determination of g m for small signal model)

13. The Definition of r  and r e and Their Relationship

14. The Hybrid-π Model (Small-Signal Equivalent Circuit)

15. Early Voltage/Finite Output Resistance

16. The Hybrid-π Small-Signal Model with the Resistance r o Included

17. The T-Model with and without the Resistance r o Included

18. Expanded Hybrid- Model for npn

19. h-Parameter Model for npn

20. BJT Hybrid-  and T Small Signal Models Summarized

21. Example Problem I

24. Analysis of Transistor Amplifier Circuits

25. Transformation of Elements ElementDC ModelAC Model ResistorRR CapacitorOpenC InductorShortL Diode+V , r f –r d = V T /I D Independent Constant Voltage Source + V S -Short Independent Constant Current Source I S Open

26. Transform This Circuit into a DC Equivalent and AC Equivalent Circuit

27. Circuits for the Analysis of a Simple Common-Emitter BJT Amplifier

28. Signal Waveforms in the BJT Amplifier Circuit

29. Circuits and Signal Waveforms for a Common-Base BJT Amplifier Circuit

30. Small Signal Equivalent Circuits for a C-E and C-B BJT Amplifier Circuits

31. Example Problem II

34. Example Problem III