* Zenes Dio de (Mt.

Abhishek Sawant)

constuction # symbol of zenet Diode.

ZeneY diode as Voltoge requloto.( Vol+age s+abiliSation circuitJ
* Note - IF the diode is heoviy doped . depietion loyer wl
be thin and consequen tly the bseak down of the
jun ction oil) occU at a lower reverSe Voitage
on the othe hond a liqhtly doped diode has a
highe breakdown oItage.
* Zener Dio de -
A PooPerly doped cystal diode which bos a sharp breakdown
Voltoqe is known as o Zener diode.
This is a PN Jun ction diode ohich is heovily d oped.
The depletion layer is very natroW
a A Zene diode is ike an Ordinary diode excep+ tha+
it is properly doped So as to have a Shap beakd own
voItaqe.
b. A zener diode S always evese connectedie it is
always rerese biosed.
A 2ener diode has Shap break down voltage called
Zener voltage Vz.
d. when FotWard biased, its characteiStics qre just
those of odiney diode.
e. The zener diode is oot
immediately bu>ntust
because i+ has entered the beakdown egion As
as the external long
cicuit connec+ed t0 +he diode limits
+he diode urrent to lesS +hon bun out Value , the
diode wi) not burn out.

Vz VE A
Ve
Anode Cathode
Rererse
Chorac+ensc
Sgmbol
JIR oF 2enes Diode
P. As +he ererse vtq is ince osed to breakdown Vt.
a lorge numbe of ele ctron-hole pais ae produced
and +he Cusent Shatply incseas es.
rereS e
Zener curent
9. This reves se Curoent s known as
Voltaqe.
& boeakdown Vtg: iS Zene
beyond zener
h. If the vo l+age 1S agin inceased
but the Vol+age
Voltaqe Zener Cuten+ 1nceaseS
emains cons+ont:
actOSS the zenet d Tode

diode os a voltoge egulator i-(Vol+oqe Stabil1se)i

* Zener acosS
egulote the vt2
used to
a. The 2ener dio de is Voia+ions in +be SuPplY V+
a Lood when +he e are

1S Conn ected
be+ ween the output
requlo+o
ne Zener used +o n e v e
undesied oc
(Nhich s
0f +he filter
Componen+s f o dc) ond lood.

Is TL
Rs

Untequl ot ed ARL
Vs Vz
Powes Supply

consists of a Curen+ limiting

requla tor
C. he Zener in Seies with the input
V+g.
resistor Rs Connec+ed
diode is Connected in Paallel
Vs arodthe Zene
Cuitn the taad KL,
is rerese bias ed
d. The Zene diode
The diode is selected ui+h a bveak down voltoge Vz
e.
acoss the load.
equal to the Voltaqe desied
Rs =
Vs-Ve \whee Is iS +be cuent fFom
Is unTegulated power SupPIy.

Is = Iz + IL
* EFfec+ of Supply voltoge voiotions i
nceose in the ineut oltoe Vs he Curent
aLt there is
thouqh Zener diode CI) increoses and the lood
Curen+ C I ) emans conston+

b. The exta Noltoqe is doopped acroSs Rs.

C' O4Put Voltaqe acoSs the lood emoins constant
Tf thee is decreose in the input oItage, curren+
Iz decoeases and the oltage dop acoss Rs is educed.
as lood Curent enains conston+ output Vol+ge
emoins Constant

* Effect of Lood curend Yoati'ons i

Q. when +he Zene d io de opeotes in +he break down
region Vz emoins constant even th ough Iz
flowing though it may change.
b when thee is eduction in load esistance, I increSes.
Iz de creases by the Sarne percentaqe & Is is kep+
Constont. TheeFot dop acoSs Rs is kep+ Consta nt
and Vo enmainS Constan+.
C when RL increases, IL decreases. Iz increoses Such
that s is lkep+ constant , thee fore output Voltage.
emains constont.
Thus, the Zener diode can be used os Volt age egul otor
vaitge
* AdVon+aqes of: Zenes Diode:
|. less expensive
2: Vsed in regulate and stabilize the vottage in a cicuit.
g. compatibitity and obtainability
4. hiqh peForrm ance Standatd.
* Disadvontages of 2ene diode!
|: I+ has elativey Poor equlot'on atio & not good
as +ansS+0r.
2
Tt concels out vta by appiying even lage Vtqin
reverse DireC+on wa s+ing electicity in process
* APPicotions: |:Votage requlation. 2- Protection gains v+s.
 * Zener Breakdowon mehansn -
P- n
a. The Zener break down occurs in heavil doped
unction diode because of +heir naro depletion
reqion.
Votaqe applied to the diode
b. when the revetse biased
incoeaSed +he nartow depletion eqion generotes
elec+ic field.
a St ong

forwad
bias region
-Ve
Izmin Io

Zene
cut in Voltage
breakdouwn
egion
I2nax.
Cons+ on+ ZenesIVoltaâc IR
oPPied t0 the diode
C. When o revesse biased vol+aqe
oeaches close to zenet Vo 1+age, the electic Field
in the depletion Teqion is Stong enough to Pu1
electons From thei Valence bond.
d. The valence elec+rons cwhich qains Sufficient enes
From the S+ong electic fievd of deple +ion reqion
tubil breaks bonding with paent atom. and become
free electons.
fom
e.These Faee elec+70ns Catty elec+ic Cuttent
One Ploce +0 ono+hes place.
E. A the zener breakdown region , a smal increase
voltage win apidly increase the electic Cusren+.
Breakdown eqion is noal
Narow
operating vegion for
a Zener diode. Deple+ion eqion Stonqerecic
fiend Pulls volence
elec+ons fromhe
IOns.

Negative Posi+ive
ion ion

Bat+e
 * Light - Emi44ing Diode cLED) ;
- Cons+uction & wotking f LED.
- If an ordinaty diode is Foswardbì osed, free electons
Cross the junction and Fal into holes. AS these electons
fol from a hiqhe energy level +o a lower eneay
levelthey odiate eneray. In 0rdinary, diod esi +his
eneqy is radio+ed in the form oF heat but in LED
eneray is rodiated in the form of ight.
By using compounds of qollium, arsenic and phosphous,
LEDs +hot rodiotes red qeen yeilow blue orange.
or infrared light con be Poduc ed.
* Light - Emitting Diode -(CED) -
LED is a special +ype of diode thot emits ight when a
current pass +houghi+ in forword biased condition.
A k
Anode JAnode
Contact,s Contac+S
Symbol of LED

p-+ype Region Ptype n-type

Ac+ive Region
Hole Ele+on
N- +y pe conductior
Subst>0te band
Liqht
Band
Gold Recombìnot'on
Cathode layer Valence
* Cons4ruction - band

a. LED is mode of thtee loyes i-e. p- +ee semiconductor

I ayer N-type sermi conduct or laye ac+ive egion.
b. N -\ayet -> electons oe majority chovge cayvies
P- layer holes ave majoty chorge carie s.
Ac+ive region ’ egual omoun+ of positive g negative
ions. C No choge cavie rs ore Ptese nt)
I4 is also known os depletion
region.
C" As +he eie ctvon -hole recombinotion occUs in p-region
is
the p layer is kept ot the top and the anode
have maxi mum
deposi+ ed a+ the edge of +he p layer +o
light emission.
deposited ot the
While fox +he cothode, qold fim is
bo +tom of +he N-type laye.
e. Semi conduc+oS Such as Gollium Arsenide CGoAs),
Gollium Arsenide phos phide C GoAsP), oY Gallium
Phosphide (Ga P) ae used in LED due +o their
Propety thot they emit eneay in the fom of
ro dio+ions while Siicon & Gemonium release in
+he Form of heot.
* Working, & opero+es in Foword
a. Jus+ ike any normol diode ,LED
bjas e. the anode is connected coith +he posi+ive
tesminal and cathode is conn ected with +henegotive
+es minol of the bottery.
b. n-+ype layes is heavily doped os compared to P
+pe layer.
c. when LED is in for ward biased, applied Pot entr'al
Stots pushing on the P-laye & the N- layer. the
deple+ion region or active oegion statts +o shnk
CStotS to educe).
d. The electrons From the n-type moteial cross +he
pn junct+lon ond re combine with holes in +he p-tpe
moteial.
e Duing its recombination ,+he elec+>ons from the
higber bond (Carnduction bond) t a hiqher energy level
than the holes in the valence band Fa| in+o +he
tower enea band CValence band) by recombine
with the holes and release the eneaqyin the form
of liqht.
f. After a fe w ecombino+ion :+he wid4h 0f deple4ion
region futher decteases 4 +he intensity of +he
Tiqnt is in ceased.
 -AmbeaTeen
-whi
*V-I charocteristics 2 -Red

Q. LED Works always on

+he Forward biasing
Con di+ion andit emits
LED
ight ohen enegized
b- To increase the Fyequenc4 VeR cel ou

of iqht emi++ed from VE

a liqht e mit+ing di ode,the
Pot en+ial barier of the diode
Rerese
is inceas ed.

* Advcntages Of LED 8 alens

|: Low cost
ysemiconduc
available in Vaiety of colous tor LED

g. Ex+eomly high speed Schip

4. long life as Compqte to LamPs.
5. Mote eliable
6. Low inheent noise. lcathode lead

* Disodvontages of LED - IAnode Lead

|. The adiont outPut Powe & i+'s Wave leng+h are
+empeotuve dependent.
2 They ae liable to qet domaged by over voltaqe
and over curtent.
3. Theoretical overall efficiency is not acheivedexcept
in specal Cooled conditorn.
* Appiica+'ons 3
|: Used in 7-segment, l6- segrnent 4 dot-natix displog.
2. optical Switching operations.
a.used in optical Com muocation
lb. Use d in buglar alom system
6. USed to indicate
digit ol igic State.
* V-I Chaacteris+ics of LED
Forward
Yeilow
Geenwhite
Current Infra Ambe
ICmA) Blue
Red
-

50

30

20 LED TyPe
& colout

>Ve
1 2
Voltoge
2 0 3
a. When the LED is forwatd biased by aPpling
Vot. a c o S S i4's termin ol then i+ eri+S theviSible
Coloured light:
constant
b. In +his Condi+ion foruw ard Cut ent is almost
+hen the
at eatly Staqe bu+ when it is ful ly 'oN'
Forward Curret is increased up constantlY.
C. The iaht inte nsiy depends upon the Forw ard Cuten+
When this Curent is high then intensity oF outPut
curtent
iqht would be hgh. The voitaqeat which
toruatvol+age.
jG incoeased Constantly Called
A. Tn reverse bias Condition the eVese or leakoge
Current is almoSt near constant but Point is
Come wher it's p-n junctiOn beaks ond oevese
Curen+ is increased constant\y in nega+ive eon.
The voita qe at which beak down is occuted s calle d
break down Voltaqe.

CMa. AS. Sauwan+)

 * MuticolouT LEDs -
when fo watd biased ond
ALED +hat emit5 one colou Called a
ColouT When re erse bËased i5
anothe
muticolour LED.
Contarn +wo Pn juctionS
a: Mul+icolour LEDs actually i-e they
reVetse -patallel
+hot are connec+ ed In
one being connected
are in Parallel with anode of
other.
+0 the cothode of +he
Positive pot ential is opetied +o the top teminal.
b. If
junc+ion on the lef+ wi liqht Curtent
the Pn
Passes though the left Ph junc+ion.
IF +he Polority of +he Voltage Soutce is reesed
C.
Cutent
the pn junc+ion on the iqht wi) light.
Passes 4h0ugh the iqht po unction.
Red when biaSed
d. Mul+icolour LE Ds ae typic olly
biased in o+her.
In one direction and Qreen when
enough
e. If a muu+i colous LEO is s witched Fast
between two Polarities , the LED wl Pooduce a
+hitd colouT. e-q. red|een LED Produce yellow
liqht when apidly Switched.
+V

Rs
 Aeplications ofF LEDs -

(1) A o Power indicatoT whethe the Powe

used to indicate
a A LED con be
iS on or not.
Switch's' is closed, Powe is applied to Lood.
b When also Flow +htough the
same +ime Curent
a t +he
Powe is oN.
EO ohich ights, |ndicate
resist0r Rs esuteS +he custent ating of LE D
c. The
is not exceeded. Rs

LED
Vin
S

Load

() Seven -5eqment Display ß

LEDS are aouped to form Seven -Segment display.
a.
Contains Seven LEDs CA B»C,DEF and G)
b: I t colled a seqment
Shaped in fiqure oF8'. each LED iS
Foruw atd biased, that LED
IF Particular LED is
C.
ces a bar of light.
or Seqment wil light and Produ
Combinotions of Seven
C" Bu forward biasing Vanous
LEDS, it is possible +o display any numbet Fom

d. External sees esistoS are included to imit

Current to Safe levels. Anodes oF al Seven LEDs
vtg. Sou>ce
are Connec+ed +0 a Common PositiVe
of +5V. hiS ar angemen+ 1S Coled as Common
LED,We have
anode +ype In order to ligbt paticulat
to qound Cathode point.

FG8
 * Photodiode& (Mo. Abhishek Sawant)
qeranium
everse -biased Silicon or
A photo-diode iS a CUrent nceases hen
which eyerSe
Pn uncton in
exposed +0 iqht.
the junction is
* con stuction -
availoble ina metallic Pckaqe.
des are
a. The Photo- dio mounted n an inSulo+ed
b. The diode is p-n
junc+ion
Plost ic Substrae.
Subs+ate is Seoled n metal case.
plastic
C. Then +he
the metal Cose +here 1s a tanspaent
d on the top of p-n
which allouS liqh+ to entet up to +he
Cwindow
junction.
anode and cathode ofF +he diode Come
e. Two leods met al ca Se.
Fomn the botton of the
out
Side of +he bottom
f. A +ab extending Faom the
the metal Case iderntifies the cathode
Potion of
Light ays
Iead.
Silicon Silicon
window Ni+ide
Diffusion mas k
coating
Anode
Depletion P-type Moterial P-N
Junc+
Layer

Bulk N -+ype silicon

N-black
Con+act 7
Cathode
Anode DiFfusion
Black Metalliza+i on
A K Cathode
Cr0SS -Sectional viewof the
photodiode

Conventionol diode is tevese biosed he

whern the
depletion region stats expanding and the CuTrent
Stat5 flvwing due +o minoity chage carieds.
b ith +he increase oF deverse Voitage the reVese
Curent nlso statS inceasinq. The same Conditon
 can be obtained in pho+o diode oithout
seveSe voI+aqe
applgina
C. The iunction of pho+o- diode is iluminated by +he
liqn+ s oure e.Cexposed to the light), +he photons
S+ike the junc+ion surface.
d. The photons impart thei enety in +he form oF
iqht +o the junc+ion. Dueto which electrons
ump into
From Valence b and qet the ene gy to
Conduc+ion bond and contibute Curen+. Tn +his
energ4 Into the
way Photo diode Convests ight
electicol energb
fore
e The cutbent cwhich Flo wS In pho to-diode be
ays are incident on i+ is Called dotk
Curent
iqht
F. AS leakaqe Cutsen+ flows in the ConVen+ional
diode Similarly the datk Curtent Flo wS in the
Photo-diode.

* V- T Characteistics of photo-diode -
Reverse voltage
Ve
-5 -4 -3 -2 +5 VE
Dark Cutent

|ooo Lux lo0

Revese
Curtent
200
1500 )ux

200o lux

400
2500 lux
Ig(uA)
mode.
evese bias
a. It is always oPetated in
hoi2on+ally in volt5
b. Reverse Voltages are plott ed vestical|y in the
and evese Cuent S plot+ed
microampers(uA).
C. Re verse curtentS Independent From the eVee
VoIta qé.
 d. when iluminotion is Zero the eVese Cutent is
appso ximo+ey Zer0 but there is o n y a Small
amount oF Cuten+ is P e s e n t and this Cutent
1S Caled d a k Cuent.
ilumino+ion, the reVeseCurrent
e. As increase +he
also increase linearl

* APplications oF photo -diodes -

photo-diode -
C) Alatm citcei+ usinq
a- Liqht fom SOuTCe is allowed
+o fall on Photo -diode fi++ed
in +he door way.
b. The evesse Cuen+ Ik wil Light
Continue t0 Flo w So long as sourc
+he iqht beam is no+ broken. 5Photo
diode
C. If the Petson Pa sses thouqh
Ligh+ DetetoT
beam
+he door +he light beam boken
and +he teveSe C uttent dops Doorway!
level. AS o e s u l t an alatm S
+o the atk C u t e n t
Sounded

(C) Counte citcuit using photo- diode -

on o
a. photo- diode may be used to Coun+ items
ConVe yos belt
b. A Source light Sends a concenta+ed beam of Irght
acsOSS aconveyor to a photo-dioe As objec+
Passes , +he Iignt beam is broken IR doops to the
dark cutent level and the count is increosed by one.
Light Soutce

Photo Diode

Counter
 * Ad Vantages of photo- diode
I+ b as lo wer noise
2. I+t has better fequency response than LDR.
3. It Can be opebated at high foequencies in otder
of | MHZ

* Dis advatages Of Photodiodes

T+ as Smal actiVe a e a .
apid inCoease in d a k Curtent with teme.
2. Tt has
3 I+ needs offset Voltage.
4. Thee is necessitY oF arm pliFication a+ low
irradionces.
* Clipping Circuits -
+he Shape of he
nWave - shopinq circuit which con+ro ls
Output Weve Form by removing o cipPIng o portion oF
The appiied wave is known os ClpPinq CYCuut
form of CliPpet as
Q. Haif wave rec+ifie is the simplest
cycleof
it Pass es ony the posi+ive Cor neqative) haif
al+enating wavefoT and Ciips ofE +he other half
Cycle.
clPPing circuits ae used in RADARS, digitol Cormputess
b.
radio r e e i v e s etC.

CiipPer citcuits a e also refe rred to as Voi+a ge

C.
Iimitets , ampli+ude Selec+os ot sliceS.
+wo componentS - an
d. FoT Cippina CitCui+ at least
equited and Some ti mes
ideal diode and resistor ore
ForFixing +heclipping
a dc bo++ery is also employ ed
leve\.
Switch when forwatd
e. The diode acts aS aclosed
bìased.
bias. ond an open Swi+ch when teveSe

1. Positive Cippet
Cscles of
The cippe \which remnoves the poSitive haif
poSi+ive cipper.
the input voI+a qe is caled as the
a. Positive Series CiPper -

D
RL
-Vmax
Input OutPut Wavefon
Wave Form
i Diode is connected Series wIt the Load.
i) Fro mobove fiq. it is Seen that when ineut i5 PoSitive
diode is everse bi0sed and So outPut ermains at
2ero. e posi+ive haif Cycle is CliPped off.
iS Duing Neqative hof cycle of the input the diode
 19 Fo wasd biased and So Negotive haif cycle aPpears
acsoss +he Output.
b. Posi+ive shunt cipper circuit8
R

+Vmoxt
D RL
- Vmux
Input OUtPut
Wave Forn Wave form
) Dio de in
paralel with the Load
i) Foom above fiq. it is se en that when input is positiVe
4he diode'Dis forw ard bias ed, ac45 like closed
Switch So con ducts heavily. So voitaqe dtop across
loadresistan ce RL iS 2er0. Thus the ou+put Voltoge
duinq Posi+ive holf cycle is zeo.
i ) Duing Negative hof cycle of the input Voltage,the
diode p' is evese biased and behaves as an open
Switch. The entire input o1taqe aPPeas aCoSS the
Lood oesist ance RL and we qet wave for mo+ Neqative
hof cycle.
2. Neqative cLipper -
Neqative clipper is one which emoves ol+he Negatie
haif cycles oF +he in put voltaqe.
a. Negative Seies Cipper;

+Vmax D +vmax
RL

Vmox
Iopu+
WaveFon
Wavefom
 D Diode is Conec+ed Seies wi+hthe Load
) From obove fig. it is Seen that when input is
Neqative. diode is everse biased. and so Du Put
emains at zero ie. Ne qative haif cycle isclipped
ofF.
I) Duinq Positive ha |f cycle the diode is Forward
biased and So posi+ive haiF Cycle appeats aCtoss
+he oUtput
b. Neqotive Shunt cipper

4Vmax +Vmax!
RL

-Vmc

Input
nave fom

i) Piode in Parallel with the Lood.

i) Foom above fiq. it is Seen that hen input is Negativ
the diode'o' is Forw ard biSedacts |ike closed
Switch So conducts heavily So Vol tage dop acoss
Load esistance RL is 2ero. Thus the output vtq.
duing Neqative haf Cycleis zeo.
) Duing positive haif cucle the diodeD' is evese
biased and behaves as an open Switch. The entire
input vol+a qe appeats actosS RL & We qet Wqve form
at positive haif cycle.
 3. Biased cliPper
move a small Portion of
SOme time i is desired +0 re
Posi+ive or Neaative half cyctes oF +he signal voltaqe s
biased ciPpers ate used For this Purpose.

a. Biosed Nego+ive Clippe

R
+Vmaxt +ume
RL

-Vmax +

Input Waveform OU+put Wavefo

i) when input Voitaqe is positive ,diode D' is reveSe

biased, behaves iike open swit ch the en+ire positive
haf Cycle appeaS acooSS +he Lood & we qet wavefom
) When input Vo |+age iS Neqa+ive but does no+ e xceeds
battey voltage'v',+he diode 'D' e mains evese
biased and most of +he input Voltage oppeats acoss
4he output. When inpu+ Siqnal exceeds the bat+e
Voltaqe 'v' the diode become forward bias and
conduc+s heaviy The out put vol+aqe is eguol +o'V
and stoys ot'v' os long as input voltage is qoeater
+han the bat+ er voitaqe.
emVes input volta9e when in put OItage
exceeds the batte VOltage.
b. Bias ed positive clippe
R
+Vmox +Vmaxl
D
RL
V
-Vmox -Vmax

Input Waveform Otpu+ Wavefo

 ) Duinq, the Nega+ive hoif C4cle the diode re mains
tevese biased theeFore olmnot entire negative
hoif Cycle appeats acroSS the Lood.

) Duing Positive half cycle input voltage exceeds +he

bo++ey Vol+aqe is removed ond input oi+oge less
than +he battey VoItage1s apPeat Qctoss the o ut Put,

4. Combino+ion cippey -
Whena potion oF bo+h poSitiVe ond Negative of each
haf cycle oF +he input Voltage is to be cipped or
Yemoved +he cIcuit Called as Combinaton Clipper.

R 4Vmaxt
Vma
Di
RL
V, V2
-V2
-Vmax -Vmax
Inpu Wavefom a Outpu+ Wave form

D For positive input Voltage when voItage exceedS the

battey voltage +, diode D condue+s cohile diode
D2 is evers ed biosed and So volta qe +Vi aPpeaS
acoSs the Output This Output Vol+ aqe +V Stys as
long os the input Siqnal voltage exceeds +Vi.
u) fo Neqative input Volta9ethe diode D, emains
everse biased and diode De ConductS only when
Voltaqe V2. So +he
input Voltage exce eds bo++eY
is
Outpu+ S+ays at-N2 So long as input Voltaqe
geater +han - V2

(MAbhishek Sawa n+)

* Clomping Circuitso
Aitcuit that places either the positive o nega+iVe
Peak oF o Siqnal at a desired dc. level 1S known as the
Clamping circuit.

+5V +iov
Positive
clamper
-5V

aA ClampingcicUit Coaclompe) essenti ally addS a

d-C. Compoent +D the Signal. The input Si qnal 5 a
Sine wave havimg o Peak-t0- peak Vo lue of loV. The
the Siqal
Clamper adds the d-c. component and pushes
zebolevel.
upwatds so tha+ +he neqative peaks Fall on
Peak Volue of tIoV and oV.
Wave form now has
b. The shape of the oiqinal Siqnal has not changed.
Such a
On ly thee is Vetical Shift nthe siqnal.
clamper is Called a poS)tIVe clmper.
C. The Negative c lamper does +he evese ie. it pushes
+he positive peaks
+he siqnol downWard Sothat
Fall on the 2eo level.
d. The clamping, circut does not Chan ge +he peak-to
- Peak o RMS Value of the Naveform.

e. A clomping cittuit Changes the peak and avetage

Values of a Wave Form. for e4. In above fiq.
The input wave form has a peak volue of5V and
Caveaqe value oVea cycle is Zero.
between lov nd ov
The clamped output VatieS

Thee foe )+he Peak value of

oF clamped outputis loV
and aveage Volue S SV.
* Posi+ive clampe -
H
RL Vout
Vin

wi+h
a" lhe in put Siqnol is assu med to be Squae WoVe
+ime peiod'T:
b The clamped outpu+ is obtained acoss RL.
C. The values oFCand RL are so Selec+ed that the
tine Constant C = CRL iS very age. This Theans that
Vol+age aco55 the capacitor will not disharge
Siqnifican+ly duing, the in+erval when diode is not
conducting
* opeotion -
a- Duing negative hoifF Cycle
of input Siqnal +he diodeis V
forw ard biased There Fore V
+ RL Vout
+he diode behaves aS a Shot.
Chatqing time conston+
CT= CRE)iS verySma| Sothat
Capacitor wil Choge +o'v'volt+
very guickiy the out put Voltage
iS acoss +he Shot Citcui+ Vout = oV.
b. Duing the positive hoif cycle
the diode everse bias ed
V
behaves as open switch.
Dischatqing tirme onstont Vout RL Vout
T= CRL is qoeate than +ine
Peiod of inPut Siqnal. the
Capacitor remains almost fully
chataed to v Volts duing+he
oFf +ime of the diode.
 PP kvL in inpu+ Loop, We have
Vt V- Vout = 0
Vout =2V
Tnput siqnal hos been Pushed upword byY Vol+ So
+hot neqative Peaks fall on +he zero level.
Vin

-V
Vouth +2V

* Negative clampe C
Vin

RL Vout
Vin

C
+
haifcycle
a.Duing the positive diodeis
Signalthe
Of the input V+
forword biosed so it behaves RL Vout
as a Short citcuit. The charqinq
+ime Constant CRf iS Vey Sall
So +hat the CapacitoY ui chaqe
+o' v 'volts Vey gickly, The
across
output vortage is direc+ly = oV.
+he Short circuit Vout
there Foe

b.uingNe qotive haif cycle the diode is evese biased

a n d behaves as an open Switch. Since +he dischaging
+he 4i
+ìme constant CRL is much greatethan
Peiod of the input siqnol the capa cito almost
 remains fully chaqed to 'v'vots during the OFP
time of +he diode.
Applying thne kvL +0 the input looe, we have,
-V-V Vout = 0
Vout = -2V
The total Swing oF +he output SiQnol i egual +0
+he +o+ol Soing of the input siqnal.
Vin

Vout RL Vout

>t

* Applica tions 0f clampes -

|. clam pess Can be Frequen+lY used in remoring the
distotions and identification of polaity of the
ciscui+s.
2. For inpro ving the revese reCovery time
3 Con be used as voI+age doubless.

4. USed in test equipment arnd other Sonot SYstems.

CMA:S-Sawon+)