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BJT, Bipolar Junction Transisor

Base Current Controls Output current. BJT, Bipolar Junction Transisor. Bollen. BJT transistorman Transistor types Bipolar Junction Transistor BJT models parameters water model NPN and PNP operation modes switch open switch closed. BJT linear, controlled current source

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BJT, Bipolar Junction Transisor

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  1. Base Current Controls Output current BJT, Bipolar Junction Transisor Bollen

  2. BJT transistorman Transistor types Bipolar Junction Transistor BJT models parameters water model NPN and PNP operation modes switch open switch closed BJT linear, controlled current source active operation characteristics DC input characteristics ac input characteristics BJT DC biasing circuits base bias base bias + collector feedback base bias + emitter feedback voltage divider AGENDA Bollen

  3. BJT, transistor man Bollen

  4. Output current controlled by input current BJT= Bipolar Junction Transistor FET = Field Effect Transistor TransistorTypes Output current controlled by input voltage Bollen

  5. Transistor=TransferResistor BJT, Bipolar Junction Transisor BE Forward bias, BC Reverse bias So low ohmic high ohmic Bollen

  6. BJT, Bipolar Junction Transisor Emitter = Sent electrons Base = Base Collector = Get electrons Bollen

  7. BJT, Models Bollen

  8. BJT, parameters Bollen

  9. BJT, Water model Bollen

  10. BJT, Water model Bollen

  11. BJT, NPN and PNP Bollen

  12. Cut-off and saturation; BJT is used as a switch Active operation Quiecent Point; BJT is used as a controlled current source, or analog amplifier BJT, Operation modes Bollen

  13. BJT, Switch open Bollen

  14. BJT, Switch closed Bollen

  15. BJT, Lineair, controlled current source Bollen

  16. BJT, active operation Bollen

  17. DC model ac model BJT, characteristics DC model; Vbe = 0V7 Ube, Uce, Ic, Ib, Ie Capitals ac model; re = 26mV/Ie ube, uce, ic, ib, ie Low cases Bollen

  18. BJT, DC input characteristics Vbe = 0V7 Bollen

  19. BJT, AC input characteristics re = 26mV/Ic The dynamic resistor can be calculated by the DC current Ic Bollen

  20. BJT, characteristics Bollen

  21. BJT, DC biasing circuits A base bias B base bias + emitter feedback C base bias + collector feedback D voltage divider Bollen

  22. BJT, base bias, introduction Base current determined by Vcc, Rb and Vbe Bollen

  23. BJT, base bias Calculate Ib and then Ic Ic directly dependent on ß variation So, for stability a “bad” circuit Bollen

  24. Q-point = Quiecient point = Working point BJT, base bias load line Load line is the loading of the transistor seen from Uce (>0V7) Vcc and Rc determines the; “open voltage” and the “short circuit current” Bollen

  25. Reliable circuit = Q-point stability BJT, base bias load line Load line is the loading of the transistor seen from Uce (>0V7) Vcc and Rc determines the; “open voltage” and the “short circuit current” Bollen

  26. Vce always > 0V7 BC junction REVERSE BJT, base bias load line If Rc too big, transistor in saturation; then; Bollen

  27. Vce always > 0V7 BC junction REVERSE BJT, base bias load line If Vcc too small, transistor in saturation; then; Bollen

  28. Calculate; Ib, Ic URc, Uc, Uce Draw output caracteristic Calculate now; Uce if ß = 40 How many % did Uce Change BJT, base bias example Ib = 47 uA, Ic = 2,35 mA, URc = 5,17 V, Uc = 6,83 V, Uce = 6,83 V Uce (for ß = 40) = 7,86 Ξ 15 % Bollen

  29. BJT, base bias example Ib = 33 uA, Ic = 2,9 mA URc = 7,9 V, Uc = 8,1 V Rb = 282,5 kΩ, Ic = 3,2 mA, Rc = 1,855 kΩ Bollen

  30. BJT, base bias example ß = 200, VRc = 8,8 V Vcc = 16 VRb = 765 kΩ Bollen

  31. BJT, base bias + emitter feedback Base current determined by Vcc, Rb, Vbe and Ve More stable for ß variations, than base bias. Bollen

  32. BJT, base bias + emitter feedback Always calculate in the smallest current Ib !! Bollen

  33. BJT, base bias + emitter feedback Load line is the loading of the transistor seen from Uce (>0V7) Vcc, Rc and Re determines the; “open voltage” and the “short circuit current” Bollen

  34. Calculate; Ib, Ic URc, Uc, Ue, Uce Draw output caracteristic BJT, base bias + emitter feedback example Ib = 6,2 uA, Ic = 0,74 mA, URc = 8,9 V, Uc = 7,1 V, Ue =-0,9 V, Uce = 8,0 V Bollen

  35. Calculate; Ib, Ie URe, Ue, Uce Draw output caracteristic BJT, base bias + emitter feedback example Ib = 24 uA, Ie = 2,9 mA, URc = 3,5 V, Ue = -2,5 V, Uce = 2,5 V Bollen

  36. BJT, base bias + collector/emitter feedback If Ic > then Uc < then Ib < If Ic > then Uc < and Ue > then Ib < Bollen

  37. BJT, base bias + collector feedback Always calculate in the smallest current Ib !! The current through Rc is not Ic but Ic + Ib, so (β+1)Ib !!! If Ic rises for any reason, then Uc falls and also Ib decreases, so then Ic decreases Bollen

  38. Calculate; Ib, ß, Ic Draw output caracteristic BJT, base bias collector feedback example Ib = 13 uA, ß = 196, Ic = 2,5 mA Bollen

  39. BJT, base bias collector/emitter feedback Always calculate in the smallest current Ib !! Bollen

  40. Calculate; Ib, Ie URc, Uc, Ue, Uce Draw output caracteristic BJT, base bias collector/emitter feedback ex Ib = 11,8 uA, Ie = 1,1 mA URc = 5,2 V, Uc = 4,8 V Ue = 1,3 V, Uce = 3,5 V Bollen

  41. Vb is a stable voltage - 0,7 V = so Ve is a stable voltage Ie is determined by Ve/ Re Ic = Ie . ß/(ß+1) Ic is very stable and nearly independent to ß variation, as long as ß is BIG in value BJT, voltage divider 2 methods of calculating Ic - neglegting Ib, use voltage divider - not neglecting Ib and use thevenin Bollen

  42. BJT, voltage divider, neglect Ib So neglegt Ib to R2, or in general Ri >> R2 In practice 10 times bigger Bollen

  43. Thevenin resistance R1 // R2 62k // 9k1= 7k9 BJT, voltage divider, exact, thevenin Thevenin voltage Bollen

  44. BJT, voltage divider, exact, thevenin 7k9 2V0 Ib = 20 uA Bollen

  45. Thevenin resistance = 6k8 Thevenin voltage = 3V1 Ib = 18,8 uA Ic = 2,25 mA re = 11,5 Ω URc = 7V4 Uc = 10V6 Ue = 2V3 Uce = 5V1 BJT, voltage divider, example Bollen

  46. Thevenin resistance = 255k Thevenin voltage = 0V0 Ib = 14,3 uA Ic = 1,9 mA re = 14 Ω URc = 17V3 Uc = 0V7 Ue = -3V7 Uce = 4V4 BJT, voltage divider, example Bollen

  47. BJT Bollen

  48. BJT Bollen

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