Transistor Structure, NPN Transistor Models-Basic Electronics and Transistor-Lecture Slides, Slides of Electronics

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EE216 ElectronicsEE216 Electronics -

LectureLecture

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LectureLecture

EE-216 ELECTRONICS -I

Acknowledgement:

The author of these slides acknowledges that

most of the slides used in this course have been taken from thecourse material provided in the CD accompanying the two text booksmentioned below.

Some of the slides have been modified and some

new slides have been added.

The author would like to appreciate

and give full credit to the efforts of the original creator of the slidesand would

categorically mention that the material used is

purely for academic purpose and not whatsoever for commercial use.

EE216 Fall 2011

2

commercial use. No commercial use of these slides is either intended and allthose accessing this material are advised to use this materialonly for academic

non-commercial purpose.

Microelectronic Circuits Sixth Edition,

by Sedra, Smith Oxford University Press

Fundamentals of Microelectronics, by Behzad Razavi, John Wiley & Sons Inc

Modified by Assistant Professor Saleem Iftekhar, SEECS NUST

NPN Transistor Current Flows

T BE

po

O

p

F T

e

p

f

p

V v

n

n

V V

n

n

exp

or

exp

Recall

)

(

,

,

≈

≈

RECALL: NPN Transistor Currents

T BE V V

S

C

e

I

i

=

BE

S

B

V V

I

i

exp

β

=

   

  

=

W

N

n

qD

A

I

A

i

N

E

S

β

C

B

i

i

=

T

V

β

1

C

E

i

i

β

β

=

T BE

V

V

S

E

e

I

i

α

=

α

α

β

−

=

1

1

≡

β

β

α α

C

E

i

i

=

BJT Cross Sectional View

Note that the collector is very large and virtuallysurrounds the base- emitter region thus no electronsescapes from being collected here.

This makes

α

very close to unity

The device is not symmetrical so emitter and collectorcannot be interchanged.

PNP Transistor Structure

PNP Transistor Models