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Bipolar JunctionTransistors

EE314

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Chapter 13: BipolarJunction Transistors

1.History of BJT2.First BJT3.Basic symbols and features4.A little bit of physics

5.Currents in BJT6.Basic configurations7.Characteristics

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The transistor wasprobably the mostimportant invention ofthe 20th Century, andthe story behind theinvention is one ofclashing egos and topsecret research.

First - BJTs

Reference:Bell Labs Museum

B. G. Streetman & S. Banerjee Solid State Electronic Devices, Prentice Hall 1999.

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Picture shows the workbench of JohnBardeen (Stocker Professor at OU) and

Walter Brattain at Bell Laboratories. Theywere supposed to be doing fundamentalresearch about crystal surfaces.

The experimental results hadn't been

very good, though, and there's a rumor thattheir boss, William Shockley, came near tocanceling the project. But in 1947, workingalone, they switched to using tremendouslypure materials.

It dawned on them that they couldbuild the circuit in the picture. It was aworking amplifier! John and Walter submitteda patentfor the first working point contacttransistor.

Interesting story

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Shockley was furious and took theirwork and invented the junction transistorand submitted a patent for it 9 days later.The three shared a Nobel Prize in 1955.Bardeen and Brattain continued inresearch (and Bardeen later won another

Nobel).

Shockley quit to start a semiconductorcompany in Palo Alto. It folded, but itsstaff went on to invent the integrated

circuit (the "chip") and to found IntelCorporation.

By 1960, all important computers usedtransistors for logic, and ferrite cores for

memory.

Interesting story

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Point-Contact Transistor first transistor ever made

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Qualitative basic operation of point-contacttransistor

Problems with first transistor

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First Bipolar Junction TransistorsW. Shockley invented the p-n junction transistorThe physically relevant region is moved to the bulk of the material

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force voltage/currentwater flow current

- amplification

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Basic models of BJT

Diode

Diode

Diode

Diode

npn transistor

pnp transistor

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Qualitative basic operation of BJTs

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Basic models of BJT

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BJTs Basic ConfigurationsFluid Flow Analogy

Difference between FET (field effect transistor)and BJTTechnology of BJTs

pnp BJT npn BJT

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BJTs Practical Aspects

Heat sink

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BJTs Testing

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BJTs Testing