Lecture 5 - Lecture 5 Announcement • Midterm 1(Next Thursday – Closed book – Can bring 2 pages of notes – Will cover upto this class(upto

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EE105 Fall 2009 Lecture 5, Slide 1 Prof. Salahuddin, UC Berkeley Announcement Midterm 1 (Next Thursday) Closed book Can bring 2 pages of notes Will cover upto this class (upto section 4.6) Prof. Tsu jae King Liu will teach next Tuesday Lecture 5
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EE105 Fall 2009 Lecture 5, Slide 2 Prof. Salahuddin, UC Berkeley OUTLINE BJT (cont’d) Large-signal model Operation in saturation mode Transconductance Small-signal model The Early effect Reading: Chapter 4.4-4.5 Lecture 5
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EE105 Fall 2009 Lecture 5, Slide 3 Prof. Salahuddin, UC Berkeley Review from the last class In the active mode, Base-Emitter is forward biased, base- collector is reverse biased. Then for an n-p-n transistor: V B >V E ; V C >VB Emitter is more heavily doped than collector Base has the least doping Base has a narrow width to reduce the recombination of carriers The current flows from emitter to base through diffusion Once the carriers reach the reverse-biased collector-base junction, the carriers are swept away by the large electric field at the junction.
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EE105 Fall 2009 Lecture 5, Slide 4 Prof. Salahuddin, UC Berkeley Review from the last class 1 exp 1 exp 1 exp T BE S E T BE S B T BE S C V V I I V V I I V V I I
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EE105 Fall 2009 Lecture 5, Slide 5 Prof. Salahuddin, UC Berkeley BJT Large Signal Model (Active Mode) A diode is placed between the base and emitter terminals, and a voltage-controlled current source is placed between the collector and emitter terminals.
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EE105 Fall 2009 Lecture 5, Slide 6 Prof. Salahuddin, UC Berkeley BJT in Saturation Mode If the collector voltage drops below the base voltage, the collector-base junction is forward biased. Base current increases, so that the current gain ( I C / I B ) decreases.
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EE105 Fall 2009 Lecture 5, Slide 7 Prof. Salahuddin, UC Berkeley BJT Output Characteristics The operating speed of the BJT also drops in saturation.
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EE105 Fall 2009 Lecture 5, Slide 8 Prof. Salahuddin, UC Berkeley BJT Large-Signal Model (Saturation Mode)
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This note was uploaded on 10/05/2009 for the course EE 105 taught by Professor King-liu during the Fall '07 term at University of California, Berkeley.

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Lecture 5 - Lecture 5 Announcement • Midterm 1(Next Thursday – Closed book – Can bring 2 pages of notes – Will cover upto this class(upto

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