Chapter 14 Output stage and power amplifier

1. Chapter 14 Output stage and power amplifier

2. Introduction 14.1 Classification of output stage 14.2 Class A output stage 14.3 Class B output stage 14.4 Class AB output stage 14.5 Biasing the class AB circuit 14.6 Power BJT’s 14.7 Variation on the Class AB configuration 14.8 IC power amplifier 14.9 MOS power transistors

3. 14.1 Classification of output stage conduction angle: 360o efficiency:25% to 50% conduction angle 180o efficiency :78.5% DC bias level DC bias level ‘0’ A class B class conduction angle 180o < θ<<360o conduction angle θ<< 180o AB class C class

4. 14.2 A class output stage 14.2.1 Transfer characteristic Emitter follower (for large signal)

5. 14.2.2 Signal waveform A class : maximum signal waveform

6. 14.2.4 Power-transfer efficiency

7. 14.3 B class output stage 14.3.1 Circuit Operating npn pnp

8. 14.3.2 Transfer Characteristic crossover distortion

9. 14.3.3 Power-transfer efficiency

10. 14.3.4 Power-consumption

11. 14.3.5 Overcome Crossover distortion 14.3.6 Single power B-class

12. 14.4 AB- class output stage 14.4.1 Circuit Operating

13. 14.4.2 Output resistance 14.5 AB- class circuit bias 14.5.1 Using diode temperature compensation (prevent thermal runaway)

14. 14.5.2 Using VBE multiplier

15. 14.6 Power BJT 14.6.3 Power consumption & temperature 14.6.1 Junction temperature 14.6.2 Thermal resistance

16. 14.6.4 BJT case & heat sink heat sink