DE LA SALLE UNIVERSITY - DASMARINASDasmarinas, Cavite, PhilippinesCOLLEGE OF ENGINEERING, ARCHITECTURE AND TECHNOLOGYENGINEERING DEPARTMENTASSIGNMENT NO. 1COMPILED BY:CABUDSAN, SARAH FATIMA C.1st Semester, 2014-201S!B"EC# I$S#%!C#O%:ENGR. KATRINA ACAPULCOAUGUST 1, 2014The Bipolar Junction Transistor or BJT was invented in 1948 at BellTelephone Laboratories, New Jersey, US!"t was the #irst $ass producedtransistor, ahead o# the %&S #ield'e##ect transistor (%&S)*T+ by a decade!Theter$bipolar re#ers tothe#act that bothelectrons andholes areinvolved in the operation o# a BJT!The $inority carrier di##usion plays theleadin, role -ust as in the .N -unction diode! The word -unction re#ers tothe #act that .N -unctions are critical to the operation o# the BJT!BJTs arealso si$ply /nown as bipolar transistors! BJT is $ade o# a heavily N'typedoped e$itter, a .'type base, and an N'type collector! This device is anN.N BJT! ( .N. BJT would have a .'e$itter, N'type base, and .'typecollector!+ N.N transistors e0hibit hi,her trans conductance and speed than.N.transistors because theelectron$obility is lar,er than thehole$obility! BJTs are al$ost e0clusively o# the N.N type since hi,hper#or$ance is BJTs1 co$petitive ed,e over %&S)*Ts!bipolar -unctiontransistor is#or$edby-oinin,threesectionso#se$iconductors with alternatively di##erent dopin,!.hysical structure o# BJT2 Bothelectronsandholesparticipateintheconductionprocess#orbipolar devices! "t consistso# two.N-unctionsconstructedinaspecial wayandconnected in series, bac/ to bac/! The transistors have 3'ter$inal devices with e$itter, base andcollector ter$inals! BJTs divided into two ,roups2 N.N and .N. transistors!%odes o# operation2 Two -unctions o# BJT can be either #orward or reversed'biased! "t can operate in di##erent $odes dependin, on the -unction bias! "t can operate in active $ode #or a$pli#ier circuits! Switchin, applications utili4e both the cuto## and saturation $odes!&peration o# the N.N transistor in the active $ode, as e$itter is heavilydoped, a lar,e nu$ber o# electrons di##use into the base (only s$all #ractionco$binewithholes+! "# thebaseisthintheseelectrons,et near thedepletion re,ion o# B5 -unction and are swept into collector i# 65B 7 8!&peration o# the N.N transistor in the saturation $ode, both *BJ and 5BJare #orward biased, the carrier in-ection #ro$ both e$itter and collector intobase!Base $inority carrier concentration chan,e accordin,ly to leadin, o#reduced slope as 6B5 increases!Saturation $ode divides into 3 ,roups2 So#t Saturation' di##usioncurrent iss$all and" veryclosetoitsactive'$ode level 9eep Saturation :e,ion ' it is s$aller than its active'$ode level Near cut'o## ' close to 4eroThe .N. transistor is the analo, to N.N BJT!5o$pare to a N.N, .N.current directions are reverse and the volta,e subscripts switched!Li/e thecut'o##, *B is a reversed biased! The active, *B id a #orward biased and5B is a reversed biased!nd the deep saturation, *B is #orward while 5Bis reversed biased!http2;;aries!ucsd!edu;NJ%B9";5LSS;*5*