1. 1 Lecture 10 Frequency response

2. 2 topics Bode diagram BJT’s Frequency response MOSFET Frequency response

3. 3 Amplifier Magnitude:Phase: Magnitude: Phase: Steady-state response

4. 4 dB (decibel)= Decimal + Bell Human hearing frequency zone : 10Hz~24kHz Most Sensitive frequency zone : 2kHz~5kHz

5. 5 Decade : Octave : Logarithmic coordinate dB Log scale

6. 6 Example(low pass)

7. 7 Magnitude: Phase:

8. 8

9. 9

10. 10 Example(high pass)

11. 11 Magnitude: Phase:

12. 12

13. 13

14. 14 The bandwidth represents the distance between the two points in the frequency domain where the signal is of the maximum signal strength.

15. 15 BJT high frequency model Depletion capacitance Emitter-base capacitance = diffusion capacitance + Base-Emitter junction capacitance Splitting resistance (refinement the lumped-component circuit)

16. 16 Low frequency ß 3-dB frequency

17. 17 Unity-gain bandwidth

18. 18 CE Amplifier

19. 19 Parallel capacitors Series capacitors Midband amplitude Bandwidth

20. 20 High frequency response: The effect of parallel capacitors

21. 21 Miller multiplier

22. 22 Example 5.18 Find the Midband gain and upper 3 dB frequency of CE amplifier. The parameters of Hybrid  model

23. 23

24. 24 Low frequency response: The effects of the series capacitors

25. 25 Consider C C1

26. 26 Consider C E

27. 27 Consider C C2

28. 28 dominant

29. 29 Example 5.19 Find the C C1, C C2 and C E the CE amplifier of the example 5.18.

30. 30 MOSFET high frequency model

31. 31

32. 32 High frequency response: The effect of parallel capacitors

33. 33 Midband amplitude Bandwidth

34. 34

35. 35

36. 36 Example 4.12 Find the Midband gain and upper 3 dB frequency of CS amplifier.

37. 37 Low frequency response: The effects of the series capacitors

38. 38

39. 39

40. 40 Example 4.13 Find the C C1, C C2 and C s the CS amplifier of the example 4.12.