Edc Brief Notes

8/13/2019 Edc Brief Notes

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ELECTRONIC DEVICES AND CIRCUITS

BRIEF NOTES

UNIT – I :: ELECTRON DYNAMICS: CRO

19 311.602 10 , 9.1 10e C m kg − −= × = × , ‘F’ force on electron in uniform electric field ‘E’

F=eE; accelerationeE

am

=

If electron with velocity ' 'v moves in field ' ' E making an angle ' 'θ can be

resolved to sin , cosv vθ θ .

Effect of agnetic Field ‘!’ on Electron.

"hen ! # $ are %er%endicular %ath is circular2

; ' 'mv m

r Period t Be Be

π = =

"hen slant with ' 'θ %ath is & 'elical.

E$()*I+- +F /*

E0E*/+-*)*I 1EF0E*I+ -E-I*I2I*32

e

a

lLS

dV =

)4E*I 1EF0E*I+ -E-I*I2I*32

m

a

eS lL

mV =

2elocity due to voltage 2,2eV

vm

=

"hen E and ! are %er%endicular and initial velocity of electron is 5ero, the %ath is

ycloidal in %lane %er%endicular to ! # E. 1iameter of ycloid=6$, whereu

Qω

= ,

E u

B= ,

Be

mω = .

UNIT – II :: SEMICONDUCTOR JUNCTION

,i e

S G have 7 electrons in covalent bands. 2alency of 7. 1o%ing with trivalent

elements makes ' ' p , 8entavalent elements makes ' 'n semiconductor.

onductivity ( )n pe n pσ µ µ = + where ,n p are concentrations of 1o%ants.

&n p

µ µ are mobility’s of electron and hole res%ectively.

- 1 -

1iode e9uation

1d

T

V nV

d s I I e

= − ÷



2; lnd T A P

d o

d i

V V N N kT r V

I I q n

∆= = = ÷∆

0 190 273; 1.602 10T C q C −= + = ×

1iode dro% changes0@ 2.2 /mv C , 0eakage current s

I doubles on 010 C

1iffusion ca%acitance is d

dqc

dv= of forward biased diode it is I µ

*ransition ca%acitance T C is ca%acitance of reverse biased diode

nV −µ 1 12 3

n to=

/E*IFIE/-

+8)/I-I+

'" F" * F" !/

C V m

V π

2m

V π

2m

V π

rmsV

2m

V 2

mV

2m

V

- 2 -

;T

kT V

q= := !olt5man onstant



γ

/i%%le factor 1.21 0.482 0.482

η

/ectification efficiency40.6% 81% 81%

PIV 8eak Inverse 2oltage m

V 6 mV

mV

UNIT – III :: FILTERS

'armonic om%onents in F" +ut%ut, 0

2 4 1 1cos 2 cos 4 .....

3 15

mV

v !t !t

π π

= − + +

- 3 -

a%acitance In%ut Filter,

Inductor In%ut Filter,ritical inductance is that value at whichdiode conducts continuously, in or half cycle.

0 FI0*E/,

2

2

12 LC γ

ω = or

1.2, 50 , , . "or #$ L in # C in %

LC µ

FI0*E/,

/ FI0*E/,

0 0)11E/,1 2

1 2

2. . .....

3

n

n

cc c

L L L

& & &

& & & γ =



EE/ 1I+1E

EE/ /E4(0)*+/

;i $ s i $

s

V V I V V

'

−= >>

$

$ $

V r

I ∆= ∆

*(E0 1I+1E

onducts in , " r

( (, $uantum mechanical tunneling in region a<<b<c.

<ve resistance b<c, normal diode c<d.

p I = %eak current, v

I = valley current; pv =%eak voltage > ?@ m2, v

v =valley voltage

.A@ 2. 'eavy 1o%ing, arrow Bunction , (sed for switching # 'F oscillators.

2)/)*+/ 1I+1E

(sed in reverse bias # as tuning variable ca%acitance.

( )

T n

T '

) C

V V =

+; n=.A for diffusion, n=.@ for alloy Cunction,

1

oT n

'

T

C C

V V

= + ÷

25

BC C

is figure of merit, -elf resonance 12

o

S T

" L C π

=

- 4 -

F"1 !ias ormal1iode .D 2 1ro%

/everse !ias



8'+*+ 1I+1E-

1iode used in reverse bias for light detection.

1ifferent materials have individual %eak res%onse to a range of wave lengths.

UNIT - IV

!B*, !i%olar Bunction *ransistor has 6 Bunctions !E, !

om%onents of current are ,nE pE

I I at EB Cunction wherenE nE

nE pE E

I I

I I I γ = =

+

γ = Emitter efficiency,* nc

nE

I

I β = trans%ortation factor.

/ ; / BE " ( BC r (= =

- 5 -

e ( c I I I = +

;c c

e (

I I

I I α β = =

1o%ing Emitter 'ighest

!ase 0owest

e c ( I I I > >



0eakage currents , ,CB* CE* EB*

I I I

( )1CE* CB*

I I β = +

A onfigurations are used on !B*, E, ! #

ommon Emitter, 2I characteristics

0; ce BE

i ie e ce

B c

V V ' + r r r

I I β

∆∆= = = = =

∆ ∆

AC Equiv!"#$ Ci%&ui$

++ !)-E 2I ')/)*E/I-*I-

- ' -

I#(u$ C)%&$"%i*$i&* Ci%&ui$ Ou$(u$ C)%&$"%i*$i&*

CE

C V

B

I

I β =



;

1

C

E

I

I

β α α

β

= =

+

; ;V CB

C c( EBi( e "( c(

E e c

I V V + r + r

I I I

∆∆= = = =

∆ ∆

UNIT - V

h< %arameters originate from e9uations of am%lifier

2 2 0 2,

i i i r " iv + i + v i + i + v= + = +

&i i

v i are in%ut voltage and current

2 2&v i are out%ut voltage and current

i+ → in%ut im%edance , ,

ie i( ic+ + + ( ), , 1

e e er r r β β +

" + → current gain , ,

"e "( "c+ + + ( ), , 1β α β +

r + → reverse voltage transfer , ,

re r( rc+ + +

o+ → out%ut admittance , ,

oe o( oc+ + +

FIE01 EFFE* */)-I-*+/, FE* is (ni%olar 1evice

- + -

COM,ARISON

!E !

-)*(/)*I+ fb fb

)*I2E fb rb

(* +FF rb rb

)80IFIE/ +8)/I-+

! E F

i ' 0+" E1 'I4'

I A

I A β 1β +

V A 'igh 'igh GH

o ' 'igh 'igh low

AC Equiv!"#$ Ci%&ui$



C#*$%u&$i# #-C)##"! (-C)##"!

-=-ource, 4=4ate, 1=1rain

4- Bunction in /everse !ias )lways

gsV ontrols 4ate "idth

2I ')/)*E/-*I-

T%#*."% C)%&$"%i*$i&* Ci%&ui$ F%/%0 C)%&$"%i*$i&*

-hockley E9uation

2

1 gs

d dss

p

V I I

V

= − ÷ ÷

, 0

1 gs

m m

p

V g g

V

= − ÷ ÷

+-FE* etal +ide -emiconductor FE*, I4FE*

D"(!"$i# T(" M*."$ S!* E#)#&""#$ M*."$

1e%letion *y%e +-FE* can work width 0 gs

V > and 0 gs

V <

T%#*."% F%/%0

C)%&$"%i*$i&* C)%&$"%i*$i&*

- -

MOSFET J,ET

'igh1010

i ' = 810−

050 ' k = Ω 1m≥ Ω

1e%letionEnhancement ode

1e%letionode

1elicate /ugged



Enhancement +-FE* o%erates with, gs t V V > , t V T+res+old Voltage=

F%/%0 C)%&$"%i*$i&* T%#*."% C)%&$"%i*$i&*

UNIT – VI :: BIASIN i# BJT 6 JFET

Fiing +%erating 8oint $ is biasing

Fied !ias Emitter -tabili5ed Feedback !ias

CC B B BE V I ' V = + Fied !ias ( )1

CC C B B B BE V ' I I ' V β = + + +

( )1 ReCC B B BE

V I ' V β = + + +

- 7 -

,%ET I Ta(le

gsV

I

SS I

.A P V 2

SS I

.@ P V

4 SS

I

P V

COM,ARISIONS

BJT FET

urrent controlled 2oltage controlled

'igh gain ed gain

!i%olar (ni%olar

*em% sensitive 0ittle effect of *

'igh 4!"8 0ow 4!"8

( ) , S GS T

V sat V V = − ( ) 2

( )ds GS T

I *N ) V V = −



2+0*)4E 1I2I1E/ !I)- EI**E/ -*)!I0IE1FIJE1 !I)-

STABILITY E8UATIONS

1 0 2 3c c BE I S I S V S β ∆ = ∆ + ∆ + ∆

1 2 3; ;C C C

C* BE

I I I S S S

I V β

∆ ∆ ∆= = =

∆ ∆ ∆

, -*)!I0I*3 F)*+/

( )1

1

B

C

S dI

dI

β

β

+=

− - must be as small as %ossible, ost ideal value =H

'ow to do determine stability factor for bias arrangementK 1erive B

C

dI

dI and

substitute in -

)m%lifier formulael

V I

i

- A A

- = , i

- measured with out%ut shorted

0Z measured with in%ut shorted

! "#$li%ie

"e+ or β

≅ ;

;i

- reβ = ;T e

V r

I = ; L

ve

' A

r = −

"#$li%ie 1

; ; Lv i e

e

' A - r

r α = = =

"#$li%ie ( ) 1 ; 1 ;ie

V i

+ A

'β = + = − ( )1

i "e E ie ' + ' += + +

' 8arameter odel E

;

1

"e

I

oe l

+ A

+ $

=

+

L

V "e

ie

- A +

+

=

- 19 -

2

1 2

CC B

V 'V

' '=

+ ,

; E E B BE C

E

V V V V I

'= − ≈

( ) ( )1 Re

.

Vcc 'c I(

I( '( V(e

β = + +

+ +



"#$li%ie ; ; . Li i( I "( V "(

i(

' ' + A + A +

+= = =

FE*

- am%lifier ( ) 0** ;

V m d d d A g ' r - '= − =

ommon 4ate )m%lifier ,1

sV m d i

m s

' A g ' -

g '= =

+

ommon 1rain1

;1

m sV o

m s m

g ' A -

g ' g = =

+ / ou%led )m%lifiers

If cut off fre9uency 1

1

2 "

'C π = ,

1 1

1

1+"n ;

1

" A

" " .

"

φ − = = ÷ + ÷

6 / , 20 /Slope dB octave dB decade= , % c+"-e 22 or "

" β is beta cut off fre9uency where 0.707 "e

+ "alls (/→

" α is α cut off fre9uency where 0.707α =

t " is 1

"e+ = gain bandwidth %roduct.

UNIT – VII :: FEED BAC AM,LIFIERS

)m%lifier gain stands for any of 2oltage am%lifier, urrent am%lifier, *rans resistance

*rans admittance am%lifier

+

− 2e feed back am%lifier de%ends on *1 * 1 , 1( (

A ve " ve " β + > − < +

Feed back reduces noise distortion, gain variation due to %arameters, increases !".

( )1 Aβ + is called de<sensitivity factor.

F""0 &; (!i.i"%*

2oltage series, voltage shunt; urrent series, current shunt

- 11 -

0

0

; ;1

"

"

i

& & A A A

A & & β

β = = =

+

i s " & & & = −

%o -ol+"e, cen+ seies

( )1 " i i

$ $ Aβ = +

1 "

A A

Aβ =

+, for all

1 "

ii

$ $

Aβ =

+

, %o -ol+"e o cen+ sn+

( )1 " o o

$ $ Aβ = + , %o cen+ seies, sn+

0

1 " o

$ $

Aβ =

+, %o -ol+"e seies "n sn+.



UNIT – VIII :: OSCILLATORS

!arkausen riterion for oscillation loo% gain =H, θ =, A?.

')/*0E3 +-I00)*+/

/3-*)0 +-I00)*+/-

*uned ckt re%laced with rystal

8hase shift oscillator

"ein !ridge +scillator

- 12 -

1

2T

" L C π

= , 1 2T L L L 0 = + ± , ;

2

1

L

Lβ = ,

+008I*- +-I00)*+/,

1 2, L L re%laced by 1 2

,C C ,

re%laced by 0; 1

2T

" LC π

=

1 s

LC ω = ,

1 p

T LC

ω =

! !

1

2 6 "

'C π = , 29 A = ,

inimum / sections A

1 2 1 2

1

2 "

' ' C C π = ,

i% R1R2R, 12 ,1

2 "

'C π = ;

13 A

β = =

8 !

1

42 6

C

" '

'C '

π

= + ÷

, 29 A = ,

inimum / sections A



- 13 -

Edc Brief Notes

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