bab 2 ee201

8/9/2019 bab 2 EE201

1/59

EE201 Semiconductor DeviceEE201 Semiconductor Device 11

TOPIC 2

~DIODES~

8/9/2019 bab 2 EE201

2/59

Doa mula kelasDoa mula kelas

Ya Tuhan, lapangkanlah dadaku, mudahkanlahYa Tuhan, lapangkanlah dadaku, mudahkanlah

segala urusanku, dan lepaskanlah kekakuan lidahku,segala urusanku, dan lepaskanlah kekakuan lidahku,

agar mereka mengerti perkataanku.agar mereka mengerti perkataanku.(Thaha: 27)(Thaha: 27)

8/9/2019 bab 2 EE201

3/59

By the end of this class, studentsBy the end of this class, students

should be able to:should be able to:~~ Understand the characteristics of diode and diode as a semiconductorUnderstand the characteristics of diode and diode as a semiconductor

device.device.

~~ Determine !" characteristic curve for silicon diode and e#$lain:Determine !" characteristic curve for silicon diode and e#$lain:

a. %nee "olta&e (Threshold volta&e )a. %nee "olta&e (Threshold volta&e )

b. 'orard current (in milli m$ere scale)b. 'orard current (in milli m$ere scale)

c. *everse current (in microm$ere scale)c. *everse current (in microm$ere scale)

d. Brea+don volta&ed. Brea+don volta&e

e. Burnin& level (hen d, "d e#ceeds ma#)e. Burnin& level (hen d, "d e#ceeds ma#)

~~ %no diode a$$lications as rectifiers.%no diode a$$lications as rectifiers.

~~ Diode as cli$$er and clam$er circuits.Diode as cli$$er and clam$er circuits.

~~ Understand other ty$es of diode:Understand other ty$es of diode:

a. -ener diodea. -ener diode

b. i&ht emittin& diode (/D)b. i&ht emittin& diode (/D)

c. hotodiodec. hotodiode

d. aser dioded. aser diode

EE201-semiconductor deviceEE201-semiconductor device 33

8/9/2019 bab 2 EE201

4/59

8/9/2019 bab 2 EE201

5/59

DiodesDiodes

~~ n effect, diodes act li+e a fla$$er valven effect, diodes act li+e a fla$$er valve ote: this is the sim$lest $ossible model ofote: this is the sim$lest $ossible model of

a diodea diode

EE201 Semiconductor DeviceEE201 Semiconductor Device 55

8/9/2019 bab 2 EE201

6/59

DiodesDiodes

~ 'or the fla$$er valve, a small $ositive~ 'or the fla$$er valve, a small $ositive$ressure is reuired to o$en.$ressure is reuired to o$en.

~ i+eise, for a diode, a small $ositive~ i+eise, for a diode, a small $ositive

volta&e is reuired to turn it on. Thisvolta&e is reuired to turn it on. This

volta&e is li+e the volta&e reuired tovolta&e is li+e the volta&e reuired to

$oer some electrical device. t is used u$$oer some electrical device. t is used u$

turnin& the device on so the volta&es atturnin& the device on so the volta&es at

the to ends of the diode ill differ.the to ends of the diode ill differ. The volta&e reuired to turn on a diode isThe volta&e reuired to turn on a diode is

ty$ically around 8.9!8. volt for a standardty$ically around 8.9!8. volt for a standard

silicon diode and a fe volts for a li&ht emittin&silicon diode and a fe volts for a li&ht emittin&

diode (/D)diode (/D)EE201 Semiconductor DeviceEE201 Semiconductor Device 66

8/9/2019 bab 2 EE201

7/59

t the ;unction, free electrons from the !ty$e

material fill holes from the !ty$e material. This

creates an insulatin& layer in the middle of the

diode called the de$letion

8/9/2019 bab 2 EE201

8/59

EE201 Semiconductor DeviceEE201 Semiconductor Device 88

DIODE-FORWARD BIAS

8/9/2019 bab 2 EE201

9/59

EE201 Semiconductor DeviceEE201 Semiconductor Device99

DIODE-REVERSE BIAS

8/9/2019 bab 2 EE201

10/59

Diode !" 5haracteristicDiode !" 5haracteristic~ 'or ideal diode, current flos only one ay~ 'or ideal diode, current flos only one ay

~ *eal diode is close to ideal~ *eal diode is close to ideal

EE201 Semiconductor DeviceEE201 Semiconductor Device 1010

8/9/2019 bab 2 EE201

11/59

Diode !" 5haracteristicDiode !" 5haracteristic

EE201 Semiconductor DeviceEE201 Semiconductor Device 1111

'orard current'orard current == current flo hen forard bias volta&e arecurrent flo hen forard bias volta&e are&iven. (in milim$ere scale)&iven. (in milim$ere scale)

*everse current*everse current ==small lea+a&e current, flo hen reverse biassmall lea+a&e current, flo hen reverse bias

volta&e (in microm$ere scale (volta&e (in microm$ere scale (>>))))

%nee "olta&e%nee "olta&e == threshold volta&e.(0i!8.7", ?e! [email protected]"). "olta&ethreshold volta&e.(0i!8.7", ?e! [email protected]"). "olta&e

that current flo immediately.that current flo immediately.Brea+don volta&eBrea+don volta&e == volta&e that reverse current flo immediately.volta&e that reverse current flo immediately.

ea+a&e 5urrentea+a&e 5urrent == Ahen a diode is reverse biased, a very smallAhen a diode is reverse biased, a very small

amount of current can and does &o in reverseamount of current can and does &o in reverse directiondirection

(i.e.o$$osite to conventional direction)(i.e.o$$osite to conventional direction) &ivin& rise to lea+a&e&ivin& rise to lea+a&e

current.current.Burnin& evelBurnin& evel !! Ahen Ahen dd and "and "dd e#ceed ma#imum, thee#ceed ma#imum, the

com$onents ill burn.com$onents ill burn.

8/9/2019 bab 2 EE201

12/59

deal Diodedeal Diode 'orard bias'orard bias= diode as a close sitch (3)= diode as a close sitch (3)

because no resistance and volta&e dro$.because no resistance and volta&e dro$.

*everse bias*everse bias== diode as o$en sitch (3''), infinitydiode as o$en sitch (3''), infinity

resistance.resistance.

EE201 Semiconductor DeviceEE201 Semiconductor Device 1212

*everse bias

3$en sitch (3'')

5athodenode

'orard bias

5lose sitch (3)

5athodenode

8/9/2019 bab 2 EE201

13/59

1313

DIODE APPLICATIONSDIODE APPLICATIONS

8/9/2019 bab 2 EE201

14/59

2-1 Half-Wave Rectiers

DIODEDIODE ability to conduct current in one direction andability to conduct current in one direction andbloc+ current in other direction bloc+ current in other direction

used in circuit calledused in circuit called */5T'/* (ac dc)

rectifierrectifieris an electrical device thatis an electrical device that

converts alternatin& current (5), hichconverts alternatin& current (5), hich

$eriodically reverses direction, to direct current$eriodically reverses direction, to direct current

(D5), hich is in only one direction, a $rocess(D5), hich is in only one direction, a $rocess+non as+non as rectification.rectification.

11

8/9/2019 bab 2 EE201

15/59

The basic function of a DC power supply isto convert an AC voltage to a constant DCvoltage (AC DC)

Either half or full-wave

rectier convert ac inputto a pulsating dc voltage.

Eliminates the uctuations- produce smooth dc voltage

Maintains a constavoltage

The basic DC power supply

8/9/2019 bab 2 EE201

16/59

~~ The a$$lied a.c si&nal across the secondary indin& chan&eThe a$$lied a.c si&nal across the secondary indin& chan&e

$olarities after each half !cycle of su$$ly a.c volta&e.$olarities after each half !cycle of su$$ly a.c volta&e.

~~ t the time of the $ositive half!cycle of su$$ly a.c volta&e,t the time of the $ositive half!cycle of su$$ly a.c volta&e,

diode is in forard biased and it conduct current in the circuits.diode is in forard biased and it conduct current in the circuits.

~~ t the time of ne&ative half!cycle of in$ut a.c volta&e, diodet the time of ne&ative half!cycle of in$ut a.c volta&e, diodebecomes reverse biased and it does not conduct current in thebecomes reverse biased and it does not conduct current in the

circuits.circuits.

~~ n this ay, current flos via the load at the time of $ositiven this ay, current flos via the load at the time of $ositive

half!cycle of in$ut a.c volta&e only here as no conduct currenthalf!cycle of in$ut a.c volta&e only here as no conduct current

throu&h the load at the time of ne&ative half!cycle in the samethrou&h the load at the time of ne&ative half!cycle in the samedirection is obtain across load for other ne#t cycle.direction is obtain across load for other ne#t cycle.

~~ But this out$ut is $ulsatin& d.c .But this out$ut is $ulsatin& d.c .

EE201 Semiconductor DeviceEE201 Semiconductor Device 1616

Half-Wave Rectier

Operation

8/9/2019 bab 2 EE201

17/59

1!1!

A half wave

rectier(ideal) allowsconduction for only180 or half of aco!plete cycle""

During rst one cycle#

Vingoes positive $diode FB$ conductcurrent

Vin goes negative $diode RB $ no

current% 0& The output fre'uencyis the sa!e as the input(sa!e shape)"

The averaevalue !DC or

!A!"#

deal diode

!odel

p

AVG

VV =

$$ %easure on &c volt'eter

The Half-Wave Rectier

ac source load resistor

8/9/2019 bab 2 EE201

18/59

ractical Diode barrier potential of 0"*& (+i) ta,en into account"

During -ve half%cycle &in!ust overco!e &potentialfor forward bias"

Example 1: Calculate the peak o/p voltage, VExample 1: Calculate the peak o/p voltage,