1 / 21

MALVINO

SIXTH EDITION. MALVINO. Electronic. PRINCIPLES. Bipolar Transistors. Chapter 6. The bipolar junction transistor has 3 doped regions. N. COLLECTOR (medium doping). P. BASE (light doping). N. EMITTER (heavy doping). In a properly biased NPN transistor, the emitter electrons

kevyn-matthews
Download Presentation

MALVINO

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SIXTH EDITION MALVINO Electronic PRINCIPLES

  2. Bipolar Transistors Chapter 6

  3. The bipolar junction transistor has 3 doped regions. N COLLECTOR (medium doping) P BASE (light doping) N EMITTER (heavy doping)

  4. In a properly biased NPN transistor, the emitter electrons diffuse into the base and then go on to the collector. RC N VCE RB P VCC N VBE VBB

  5. IC IC IB IB IE IE IC IC bdc = adc = IB IE Conventional flow Electron flow IE = IC + IB IC @ IE IB << IC

  6. The common emitter connection has two loops: the base loop and the collector loop. RC RB VCE VCC VBE VBB

  7. Subscript notation • When the subscripts are the same, the voltage represents a source (VCC). • When the subscripts are different, the voltage is between two points (VCE). • Single subscripts are used for node voltages with ground serving as the reference (VC).

  8. The base circuit is usually analyzed with the same approximation used for diodes. VBB - VBE RC IB = RB VCE VCC RB VBE VBB

  9. 100 mA 80 mA 60 mA 40 mA 20 mA 0 mA A graph of IC versus VCE (Note that each new value of IB presents a new curve.) 14 12 10 IC in mA 8 6 4 2 6 16 2 4 10 12 0 14 18 8 VCE in Volts This set of curves is also called a family of curves.

  10. Regions of operation • Cutoff - - - used in switching applications • Active - - - used for linear amplification • Saturation - - - used in switching applications • Breakdown - - - can destroy the transistor

  11. Transistor circuit approximations • First: treat the base-emitter diode as ideal and use bIB to determine IC. • Second: correct for VBE and use bIB to determine IC. • Third (and higher): correct for bulk resistance and other effects. Usually accomplished by computer simulation.

  12. The second approximation: bdcIB VBE = 0.7 V VCE

  13. VBB - VBE IB = RB 5 V - 0.7 V = 43 mA IB = RC 100 kW 100 kW VCC RB VBE = 0.7 V 5 V VBB

  14. IC = bdc IB IC = 100 x 43 mA = 4.3 mA RC 100 kW bdc = 100 VCC RB IB = 43 mA 5 V VBB

  15. VRC = IC x RC VRC = 4.3 mA x 1 kW = 4.3 V 1 kW RC IC = 4.3 mA 100 kW 12 V VCC RB IB = 43 mA 5 V VBB

  16. IC = 4.3 mA VCE = VCC - VRC VCE = 12 V - 4.3 V = 7.7 V 1 kW RC VCE 100 kW 12 V VCC RB IB = 43 mA 5 V VBB

  17. Typical Breakdown Ratings • VCB = 60 V • VCEO = 40 V • VEB = 6 V • Note: these are reverse breakdown ratings

  18. A graphic view of collector breakdown 14 12 10 IC in mA 8 6 4 2 0 50 VCE in Volts

  19. Typical Maximum Ratings • IC = 200 mA dc • PD = 250 mW (for TA = 60 oC) • PD = 350 mW (for TA = 25 oC) • PD = 1 W (for TC = 60 oC)

  20. Typical “On Characteristics” IC in mA hFE(min) hFE(max) 0.1 40 ___ 1 70 ___ 10 100 300 50 60 ___ 100 30 ___

  21. Troubleshooting • Look for gross voltage errors. • First approximation and mental estimates will usually suffice. • Resistors don’t short but circuit boards can. • Circuit boards can and do open. • Junctions can and do short. • Junctions can and do open.

More Related