BJT, Bipolar Junction Transisor Base Current Controls Output current Bollen

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

BJT, transistor man Bollen

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

BJT, Bipolar Junction Transisor Transistor = Transfer Resistor BE Forward bias, BC Reverse bias So low ohmic high ohmic Bollen

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

BJT, Models Bollen

BJT, parameters Bollen

BJT, Water model Bollen

BJT, Water model Bollen

BJT, NPN and PNP Bollen

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

BJT, Switch open Bollen

BJT, Switch closed Bollen

BJT, Lineair, controlled current source Bollen

BJT, active operation Bollen

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

BJT, DC input characteristics Vbe = 0V7 Bollen

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

BJT, characteristics Bollen

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

BJT Bollen

BJT Bollen