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    Bipolar Junction Transistors (BJTS) P-N-P BJT Configurations

    Uploaded by

    minhduy223
    This document provides information about bipolar junction transistors (BJTs) including: - BJTs are bipolar devices made of two p-n junctions in a p-n-p or n-p-n configuration. - They can operate in common base, common emitter, or common collector modes. Active and saturation modes are described. - Key parameters like emitter efficiency, base transport factor, and common emitter current gain are defined. Current components in active mode are shown. - I-V characteristics of common base and common emitter configurations are illustrated and early effect is discussed.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Bipolar Junction Transistors (BJTS) P-N-P BJT Configurations

    Uploaded by

    minhduy223
    44 views3 pages
    This document provides information about bipolar junction transistors (BJTs) including: - BJTs are bipolar devices made of two p-n junctions in a p-n-p or n-p-n configuration. - They can operate in common base, common emitter, or common collector modes. Active and saturation modes are described. - Key parameters like emitter efficiency, base transport factor, and common emitter current gain are defined. Current components in active mode are shown. - I-V characteristics of common base and common emitter configurations are illustrated and early effect is discussed.

    Original Description:

    semiconductor material science

    Original Title

    BJThandout

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    © © All Rights Reserved

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    This document provides information about bipolar junction transistors (BJTs) including: - BJTs are bipolar devices made of two p-n junctions in a p-n-p or n-p-n configuration. - They can operate in common base, common emitter, or common collector modes. Active and saturation modes are described. - Key parameters like emitter efficiency, base transport factor, and common emitter current gain are defined. Current components in active mode are shown. - I-V characteristics of common base and common emitter configurations are illustrated and early effect is discussed.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    44 views3 pages

    Bipolar Junction Transistors (BJTS) P-N-P BJT Configurations

    Uploaded by

    minhduy223
    This document provides information about bipolar junction transistors (BJTs) including: - BJTs are bipolar devices made of two p-n junctions in a p-n-p or n-p-n configuration. - They can operate in common base, common emitter, or common collector modes. Active and saturation modes are described. - Key parameters like emitter efficiency, base transport factor, and common emitter current gain are defined. Current components in active mode are shown. - I-V characteristics of common base and common emitter configurations are illustrated and early effect is discussed.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 3

    5/29/2014

    1
    Bipolar Junction Transistors
    (BJTs)
    BipolarDevice:Bothelectronsandholesparticipateinconductionprocess
    Madeof2pnjunctions
    PNP:(1)heavilydopedp+(emitter)
    (2)narrow,moderatelydopedn(base)
    widthofbaseW
    B
    <<Lp (diffusionlengthofminoritycarrier)
    (3)moderatelydopedp(collector)
    p-n-p BJT Configurations
    t t
    output
    CommonBase CommonEmitter CommonCollector
    GAINMODE
    input
    input
    output
    BJT Modes of Operation
    Junctionpolaritiesandminoritycarrier
    distributionsofapnp transistorunder
    fourmodesofoperation
    Region of
    Operation
    Description
    Active Small base current controls a
    large collector current
    Saturation V
    CE(sat)
    ~ 0.2V, V
    CE
    increases
    with I
    C
    Cutoff Achieved by reducing I
    B
    to 0,
    Ideally, I
    C
    will also equal 0.
    ThermalEquilibrium ActiveMode
    p
    +
    p-n-p Transistor Active Bias Mode
    Few recombine
    in the base
    Most holes
    diffuse to
    collector
    Large injection
    of Holes
    Collector Fields drive holes
    far away where they cant
    return thermionically
    Current Components in a p-n-p Transistor
    under Active Mode
    I
    E
    =I
    Ep
    +I
    En
    I
    C
    =I
    Cp
    + I
    Cn
    I
    B
    = I
    E
    -I
    C
    = I
    En
    + (I
    Ep
    -I
    Cp
    )- I
    Cn
    En Ep
    Ep
    E
    Ep
    I I
    I
    I
    I
    +
    = = 1 0 s s
    Ep
    Cp
    T
    I
    I
    = o 1 0 s o s
    T
    Emitter Efficiency:
    Base Transport Factor:
    Common Base dc Current Gain:
    T o
    E
    Cp
    I
    I
    o o =
    Common Emitter dc Current Gain:
    o
    B
    C
    o
    o
    I
    I
    o
    o
    |

    =
    A
    A

    1
    B E C En
    (
    Ep Cp
    )
    Cn
    , I
    C
    =
    o
    I
    E
    + I
    CBO
    , I
    C
    =
    o
    I
    B
    + I
    CEO
    5/29/2014
    2
    Common Base Configuration I-V
    Ic(mA)
    T o
    E
    Cp
    I
    I
    o o =
    I
    C
    =
    o
    I
    E
    + I
    CBO
    Apply asmall V
    CB
    (<0) to reduceIc to zero. Ic=I
    E
    for an ideal BJ T, it is independent of V
    CB
    Input: V
    EB
    , V
    CB
    ; Output: I
    E
    , I
    C
    Minority Carrier Distributions in the
    Base Region of a p-n-p
    Saturation Mode
    Both junctions forward biased.
    Active Mode
    V
    BC
    = 0 and V
    BC
    > 0
    Common Emitter Configuration I-V
    o
    B
    C
    o
    o
    I
    I
    o
    o
    |

    =
    A
    A

    1
    I
    C
    =
    o
    I
    B
    + I
    CEO
    Apply asmall in I
    B
    to givelargechangein Ic. for an ideal BJ T, I
    B,
    Icindependent of V
    EC
    Input: V
    EB
    , I
    B
    ; Output: V
    EC
    , I
    C
    The collector currents for different
    base currents meet at V
    A
    Early Effect (Base Width Modulation)
    and Early Voltage (V
    A
    )
    base currents meet at V
    A
    .
    Ideally I
    C
    is independent of V
    EC
    (when VEC > 0) for a given I
    B
    , if W
    B
    is constant.
    V
    CB
    narrows W
    B
    leading to higher diffusion current in B, hence higher
    o
    and higher I
    C
    (a) Bipolar transistor connected in the common-emitter configuration. (b)
    Small-signal operation of the transistor circuit.
    Current Gain as a Function of Operating Frequency.
    5/29/2014
    3
    (a) Schematic of a transistor switching circuit. (b) Switching operation from
    cutoff to saturation.
    n-p-n Heterojunction Bipolar Transistor (HBT)
    ] exp[
    ) (
    kT
    E
    N
    N EB g
    B
    E
    o
    A
    |

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