Ete411 Lec15
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Lecture on Introduction of Semiconductor at North South University as the undergraduate course (ETE411)...

Lecture on Introduction of Semiconductor at North South University as the undergraduate course (ETE411)
=======================
Dr. Mashiur Rahman
Assistant Professor
Dept. of Electrical Engineering and Computer Science
North South University, Dhaka, Bangladesh
http://mashiur.biggani.org

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Ete411 Lec15 Ete411 Lec15 Presentation Transcript

  • ETE444 :: Lec15
    Dr. MashiurRahman
    Copyright: Semiconductor Physics And Devices 3rd ed. - J. Neamen
  • Forward-active mode
  • Injection and collection of electrons
  • iE1= due to the flow of electrons injected into the base = ic
    α = Common-Base current gain
    β = Common-Emitter gain
  • Four operation mode of bipolar transistor
    n
  • Cuttoff mode
    VCB> 0
    VBE < 0
    B-E = reverse biased
     Mejority carrier electrons from the emitter will not injected into the bias
    Minority carrier distribution
  • Forward active mode
    The B-E junction becomes forward biased, an emitter current will be generated and the injection of electrons into the base results in a collector current
    VCB> 0
    VBE > 0
    Minority carrier distribution
  • Inverse active
    The B-E forward biased and C-B
    VCB < 0
    VBE < 0
    Minority carrier distribution
  • Saturation mode
    Both B-E and B-C junctions are forward biased and the collector current no longer controlled by the B-E voltage.
    VCB< 0
    VBE > 0
    Minority carrier distribution
  • Application
    Voltage amplifier by Bipolar Transistors
    Switching
  • Voltage amplifier by Bipolar Transistors
    Input sinusoidal signal voltage
    Sinusoidal voltage across the Rc resistor
    Sinusoidal collector currents
    Sinusoidal base currents
  • Switching
    Storage time
    Raise time
    Fall time
    Circuit used for transistor switching
    Delay time
  • Switching :: Important parameter
    Current gain
    lower doping in the base region is used.
    Switching time
    The transistor can be doped with gold to introduce midgap recombination centers and thus reduce the switching time.