A Presentation On Bjt.ppt 5c11e

POOJA KUMARI FED PRESENTATION

BJT , Fundamentals of BJT operation , amplification

Contents: Transistor:a view of classification BJT : sections ( E,B,C) and types Operation of npn and pnp Modes of operation Transistor circuit configuration Characteristics of CB and CE D.C. load line , operating point Transistor as an amplifier 11/5/2015

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TRANSISTOR CIRCUIT CONFIGURATIONS Depending on the polarities of bias voltage connected to the transistor terminals following are the types : 1. common base (CB) 2. Common emitter (CE) 3. Common collector (CC)

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TRANSISTOR BJT (BIPOLAR JUNCTION TRANSISTOR )

FET

(FIELD EFFECT TRANSISTOR)

JFET MESFET(METAL MISFET (JUNCTION FET) SEMINCONDUCTOR (METAL FET)

INSULATOR SC FET) 11/5/2015

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BJT (BIPOLAR JUNCTION TRANSISTOR) •A junction transistor is simply a sandwich of one type of semiconductor material between two layers of the other type.

Types : 1) n-p-n 2) p-n-p

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n-p-n

P-n-p 11/5/2015

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Sections in transistor: I. Emitter II. Base III. Collector 1.Emitter : left section of transistor  supply majority charge carriers Heavily doped (10^19 cm^-3) 2.Base : Middle section of transistor Lightly dopes (10^16 cm-3) Very thin (10^-6 cm^-3) 11/5/2015

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3.Collector : •Right hand section of transistor •Main function is to collect majority charge carriers •Moderately doped (from 10^14 to 10^19) •Largest among the three regions

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Operation of PNP transistor :

holes of p-region repelled by VBE .

Potential

barrier at junction reduced. Hence , holes cross junction penetrate Nregion thus constitute IE 11/5/2015

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Base region width is thin ,hence less recombination with holes of p-region produces IB very small. Remaining holes drift across the base enter collector region and swept up by the negative collector voltage VCC .This constitutes IC.

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Operation of NPN transistor :

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 The n-side e-(emitter) are repelled from VEE , hence IE constitute .  e- crosses p-type base region, A few ecombine with the holes in P-region and rest are swept away by Vcc ,collector voltage . Thus constitute Ic.

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COMMON BASE CHARACTERISTICS : 1. INPUT CHARACTERISTISTICS :

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OUTPUT CHARACTERISTICS

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Transistor as an Amplifier 1. Common base (CB) amplifier :

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2. Common emitter ( CE) amplifier:

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3.Common collector (CC) amplifier :

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THANK YOU ------------------------------------------------

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