1. Microelectronics Circuit Analysis and Design
Donald A. Neamen
Chapter 5
The Bipolar Junction Transistor

2. In this chapter, we will:
Discuss the physical structure and operation of the bipolar junction transistor.
Understand the dc analysis and design techniques of bipolar transistor circuits.
Examine three basic applications of bipolar transistor circuits.
Investigate various dc biasing schemes of bipolar transistor circuits, including integrated circuit biasing.
Consider the dc biasing of multistage or multi-transistor circuits.

3. Cross Section of Integrated Circuit npn Transistor

4. Modes of Operation Forward-Active B-E junction is forward biased
B-C junction is reverse biased
Saturation
B-E and B-C junctions are forward biased
Cut-Off
B-E and B-C junctions are reverse biased
Inverse-Active (or Reverse-Active)
B-E junction is reverse biased
B-C junction is forward biased

5. npn BJT in Forward-Active

6. Electrons and Holes in npn BJT

7. Electrons and Holes in pnp BJT

8. Circuit Symbols and Current Conventions

9. Current Relationships

10. Common-Emitter Configurations

11. Common-Base Configuration

12. Current-Voltage Characteristics of a Common-Base Circuit

13. Current-Voltage Characteristics of a Common-Emitter Circuit

14. Early Voltage/Finite Output Resistance

15. Effects of Leakage Currents on I-V Characteristics

16. Effect of Collector-Base Breakdown on Common Base I-V Characteristics

17. Effect of Collector-Base Breakdown on Common Emitter I-V Characteristics

18. DC Equivalent Circuit for npn Common Emitter

19. DC Equivalent Circuit for pnp Common Emitter

20. Load Line

21. Problem-Solving Technique: Bipolar DC Analysis
Assume that the transistor is biased in forward active mode
VBE = VBE(on), IB > 0, & IC = bIB
Analyze ‘linear’ circuit.
Evaluate the resulting state of transistor.
If VCE > VCE(sat), assumption is correct
If IB < 0, transistor likely in cutoff
If VCE < 0, transistor likely in saturation
If initial assumption is incorrect, make new assumption and return to Step 2.

22. Voltage Transfer Characteristic for npn Circuit

23. Voltage Transfer Characteristic for pnp Circuit

24. Digital Logic
Inverter
NOR gate

25. Bipolar Inverter as Amplifier

26. Effect of Improper Biasing on Amplified Signal Waveform

27. Single Base Resistor Biasing

28. Common Emitter with Voltage Divider Biasing and Emitter Resistor

29. Integrated Circuit Biasing

30. Multistage Cascade Transistor Circuit

31. Multistage Cascode Transistor Circuit