Download presentation

1
**BJT, Bipolar Junction Transisor**

Base Current Controls Output current Bollen

2
**AGENDA 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 Bollen

3
BJT, transistor man Bollen

4
**Transistor Types Output current controlled by input current BJT =**

Bipolar Junction Transistor FET = Field Effect Transistor Output current controlled by input voltage Bollen

5
**BJT, Bipolar Junction Transisor**

Transistor = Transfer Resistor 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
**BJT, Operation modes 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 Bollen

13
BJT, Switch open Bollen

14
BJT, Switch closed Bollen

15
**BJT, Lineair, controlled current source**

Bollen

16
BJT, active operation Bollen

17
**BJT, characteristics DC model ac model**

DC model; Vbe = 0V 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
**BJT, base bias load line Q-point = Quiecient point = Working point**

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
**BJT, base bias load line Reliable circuit = Q-point stability**

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
**BJT, base bias load line Vce always > 0V7 BC junction REVERSE**

If Rc too big, transistor in saturation; then; Bollen

27
**BJT, base bias load line Vce always > 0V7 BC junction REVERSE**

If Vcc too small, transistor in saturation; then; Bollen

28
**BJT, base bias example Calculate; Ib, Ic URc, Uc, Uce**

Draw output caracteristic Calculate now; Uce if ß = 40 How many % did Uce Change 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
**BJT, base bias + emitter feedback example**

Calculate; Ib, Ic URc, Uc, Ue, Uce Draw output caracteristic 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
**BJT, base bias + emitter feedback example**

Calculate; Ib, Ie URe, Ue, Uce Draw output caracteristic 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
**BJT, base bias collector feedback example**

Calculate; Ib, ß, Ic Draw output caracteristic 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
**BJT, base bias collector/emitter feedback ex**

Calculate; Ib, Ie URc, Uc, Ue, Uce Draw output caracteristic 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
**BJT, voltage divider 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 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
**BJT, voltage divider, exact, thevenin**

Thevenin resistance R1 // R2 62k // 9k1= 7k9 Thevenin voltage Bollen

44
**BJT, voltage divider, exact, thevenin**

7k9 2V0 Ib = 20 uA Bollen

45
**BJT, voltage divider, example**

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 Bollen

46
**BJT, voltage divider, example**

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 Bollen

47
BJT Bollen

48
BJT Bollen

Similar presentations

OK

Copyright © 2012, Elsevier Inc. All rights Reserved. 1 Chapter 7 Modeling Structure with Blocks.

Copyright © 2012, Elsevier Inc. All rights Reserved. 1 Chapter 7 Modeling Structure with Blocks.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Best ppt on earth day for kids Ppt on leadership styles in banking sector Ppt on technology in agriculture Upload and view ppt online maker Free ppt on management of natural resources Free ppt on brain machine interface insect Ppt on operating system linux Download ppt on oxidation and reduction in cellular Ppt on effect of global warming on weather service Best ppt on geothermal energy