7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 1/6

 NAME PICTURE SCHEMATIC DIAGRAM MEANING

Bipolar JunctionTransistors

Bipolar Junction Transistors are transistors which area!e up o" # re$ions% the &ase% the collector% an! theeitter' Bipolar Junction transistors% unli(e )ETtransistors% are current*controlle! !e+ices' A sallcurrent enterin$ in the &ase re$ion o" the transistor

causes a uch lar$er current "low "ro the eitter tothe collector re$ion'

Bipolar ,unction transistors coe in two ain t-pes% NPN an! PNP' A NPN transistor is one in which thea,orit- current carrier are electrons' Electron "lowin$"ro the eitter to the collector "ors the &ase o" thea,orit- o" current "low throu$h the transistor' Theother t-pe o" char$e% holes% are a inorit-' PNPtransistors are the opposite' In PNP transistors% the

a,orit- current carrier are holes'

.+erall% &ipolar ,unction transistors are the onl- t-pe o"transistor which is turne! on &- current input /input intothe &ase0' This is &ecause BJTs ha+e the lowest inputipe!ance o" all transistors' The low ipe!ance /orresistance0 allows current to "low throu$h the &ase o"the transistor' Because o" this low ipe!ance also !oBJTs ha+e the hi$hest apli"ication o" all transistors'The !ownsi!e o" BJTs is &ecause the- ha+e low inputipe!ance% the- can cause loa!in$ in a circuit' 1oa!in$

is when a !e+ice can !raw si$ni"icant current "ro acircuit% thus !istur&in$ a circuit2s power source'

7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 2/6

)iel! E""ectTransistors

)iel! E""ect Transistors are transistors which are a!eup o" # re$ions% a $ate% a source% an! a !rain' Unli(e

 &ipolar transistors% )ETs are +olta$e*controlle! !e+ices'A +olta$e place! at the $ate controls current "low "ro

the source to the !rain o" the transistor'

)iel! E""ect transistors ha+e +er- hi$h input ipe!ance%"ro se+eral e$ohs /M30 o" resistance to uch%uch lar$er +alues' This hi$h input ipe!ance causesthe to ha+e +er- little current run throu$h the'/Accor!in$ to oh2s law% current is in+ersel- a""ecte!

 &- the +alue o" the ipe!ance o" the circuit' I" theipe!ance is hi$h% the current is +er- low'0 So )ETs

 &oth !raw +er- little current "ro a circuit2s powersource' Thus% this is i!eal &ecause the- !on2t !istur& the

ori$inal circuit2s power eleents to which the- are

connecte! to' The- won2t cause the power source to &eloa!e! !own' The !raw&ac( o" )ETs is that the- won2t

 pro+i!e the sae apli"ication that coul! &e $otten

"ro &ipolar transistors' Bipolar transistors are superiorin the "act that the- pro+i!e $reater apli"ication% e+enthou$h )ETs are &etter in that the- cause less loa!in$%are cheaper% an! easier to anu"acture'

)iel! E""ect Transistors coe in 4 ain t-pes5 J)ETsan! M.S)ETs' J)ETs an! M.S)ETs are +er- siilar

 &ut M.S)ETs ha+e e+en hi$her input ipe!ance

+alues than J)ETs' This causes e+en less loa!in$ in acircuit'

7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 3/6

Sall Si$nalTransistors

Sall Si$nal Transistors are transistors that are use! priaril- to apli"- low*le+el si$nals &ut can also

"unction well as switches'

Transistors coe with a +alue% calle! the h)E +alues%

which !enotes how $reatl- a transistor can apli"-input si$nals' T-pical h)E +alues "or sall si$naltransistors ran$e "ro 67 to 877% with a9iu Ic/collector current0 ratin$s "ro a&out :7 to ;77A'The- coe in NPN an! PNP "ors' Ma9iuoperatin$ "re<uencies ran$e "ro a&out 6 to #77 MH='

As a !esi$n note% sall si$nal transistors are use! priaril- when apli"-in$ sall si$nals% such as a "ew+olts an! onl- when usin$ illiaperes o" current'>hen usin$ lar$er +olta$e an! current /lar$er power0%

usin$ an- +olts or aperes o" current% a powertransistor shoul! &e use!'

7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 4/6

Sall Switchin$Transistors

Sall Switchin$ Transistors are transistors that are use! priaril- as switches &ut which can also &e use! as

apli"iers' T-pical h)E +alues "or sall switchin$transistors ran$e "ro 67 to 477% with a9iu Ic

ratin$s "ro a&out 67 to 6777A' The- coe in NPN

an! PNP "ors'

In ters o" "or !esi$n% sall switchin$ transistors areuse! priaril- as switches' Thou$h the- a- &e use! asan apli"ier% their h)E +alue onl- ran$es to a&out 477%which eans the- are not capa&le o" the apli"icationo" sall si$nal transistors% which can ha+eapli"ication o" up to 877' This a(es sall switchin$

transistors ore use"ul "or switchin$% thou$h the- a- &e use! as &asic apli"iers to pro+i!e $ain' >hen -ou

nee! ore $ain% sall si$nal transistors woul! wor(

 &etter as apli"iers'

Power Transistors Power transistors are suite! "or applications where a loto" power is &ein$ use!* current an! +olta$e'

The collector o" the transistor is connecte! to a etal &ase that acts as a heat sin( to !issipate e9cess power'

T-pical power ratin$s ran$e "ro aroun! 67 to #77 >%with "re<uenc- ratin$s "ro a&out 6 to 677 MH='Ma9iu Ic +alues ran$e &etween 6 to 677 A' Powertransistors coe in NPN% PNP% an! Darlin$ton /NPN orPNP0 "ors'

7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 5/6

Hi$h )re<uenc-Transistors

Hi$h )re<uenc- /R)0 Transistors are transistors that areuse! "or sall si$nals that run at hi$h "re<uencies "or

hi$h*spee! switchin$ applications'

These are transistors that are use! "or hi$h "re<uenc-

si$nals an! ust &e a&le to switch on an! o"" at +er-hi$h spee!s' Hi$h "re<uenc- transistors are use! in H)%?H)% UH)% CAT?% an! MAT? apli"ier an! oscillatorapplications' The- ha+e a a9iu "re<uenc- ratin$ o" a&out 4777 MH= an! a9iu Ic currents "ro 67 to;77A' The- are a+aila&le in &oth npn an! pnp "ors'

Phototransistors Phototransistors are li$ht*sensiti+e transistors'

A coon t-pe o" phototransistor rese&les a &ipolartransistor with its &ase lea! reo+e! an! replace! witha li$ht*sensiti+e area' This is wh- a phototransistor has

onl- 4 terinals instea! o" the usual #' >hen thissur"ace area is (ept !ar(% the !e+ice is o""' Practicall-%

no current "lows "ro the collector to eitter re$ion'Howe+er% when the li$ht*sensiti+e re$ion is e9pose! to

li$ht% a sall &ase current is $enerate! that controls auch lar$er collector*to*eitter current'

Just li(e re$ular transistors% phototransistors can &e &oth &ipolar or "iel! e""ect transistors' )iel!*e""ect

 phototransistors /photo)ETs0 are li$ht*sensiti+e "iel!*e""ect transistors' Unli(e photo&ipolar transistors%

 photo)ETs use li$ht to $enerate a $ate +olta$e that isuse! to control a !rain*source current' Photo)ETs are

e9treel- sensiti+e to +ariations in li$ht an! are ore

7/24/2019 Transistors Lololol

http://slidepdf.com/reader/full/transistors-lololol 6/6

"ra$ile% electricall- spea(in$% than &ipolar phototransistors'

Uni,unctionTransistors

Uni,unction transistors are three*lea! transistors that acte9clusi+el- as electricall- controlle! switches@ the- arenot use! as apli"iers'

This !i""ers "ro other transistors in that $eneraltransistors usuall- pro+i!e the a&ilit- to act as a switch

an! also as a an apli"ier' But a uni,unction transistor!oes not pro+i!e an- !ecent t-pe o" apli"ication

 &ecause o" the wa- it is constructe!' It2s sipl- not!esi$ne! to pro+i!e a su""icient +olta$e or current

 &oost'

The three lea!s o" a uni,unction transistor are B6% B4%an! an eitter lea!% which is the lea! which recei+esthe input current' The &asic operation o" a UJT is

relati+el- siple' >hen no potential !i""erence/+olta$e0 e9ists &etween its eitter an! either o" its

 &ase lea!s /B6 or B40% onl- a +er- sall current "lows"ro B4 to B6' Howe+er% i" a su""icientl- lar$e positi+e

tri$$er +olta$e* relati+e to its &ase lea!s* is applie! tothe eitter% a lar$er current "lows "ro the eitter an!

co&ines with the sall B4*to*B6 current% thus $i+in$rise to lar$e B6 output current' Unli(e other transistors*

where the control lea!s pro+i!e little a!!itional current*the UJT is ,ust the opposite' Its eitter current is the

 priar- source o" current "or the transistor' The B4 toB6 current is onl- a +er- sall aount o" the totalco&ine! current' This eans that uni,unctiontransistors are not suita&le "or apli"ication purposes%

 &ut onl- "or switchin$'