ECE104L Experiment 1

Interpretation Interpretation Of Results:

Experiment 1: Small Signal Amplier is an experiment done by making use of transistors as ampliers. Tese ampliers in!rease te amplitude of  signals. "uring te experiment# $e $ere tasked to !reate di%erent kinds of  !ir !ir!uit !uit

repr epresen esenti ting ng

te te

di%e di%errent ent

type types s

of

ampl ampli ier ers s

&!om &!ommo mon' n'ba base se##

!ommon !ommon'em 'emitt itter er## and !ommon !ommon'!o '!olle lle!to !tor(. r(. As prese presente nted# d# te exper experime iment nt in)ol)es in)ol)es tree tree !ir!uit !ir!uit arrangem arrangements ents of small'sign small'signal al ampliers ampliers namely te !ommon !ommon'ba 'base# se# !ommon !ommon'em 'emitt itter# er# and te !ommon !ommon'!o '!olle lle!to !torr. Ea! Ea! !ir!ui !ir!uitt arrangement of small'signal amplier as its o$n !ara!teristi!.

*art 1 of te experiment: !ommon'base small'signal amplier $as performed $ere te emitter a!ts as te input terminal and te !olle!tor as te output termi terminal nal.. "uring "uring te exper experime iment# nt# making making use of te os!ill os!illos! os!ope ope $e !an obser)e tat tis !ir!uit amplies )ery $ell# and troug te )alues of te input )oltage and output )oltage $e !an obser)e o$ greater te output )oltage as be!ome !ompared to its input )oltage. *art + of te experiment: !ommon emitter small'signal amplier makes use of te base as te input terminal and te !olle!tor as te output terminal. Te !ommon emitter,s grap in te os!illos!ope exibited to us a re)erse pase re)ersal seeing te di%er di%eren! en!e e in te input and output output )oltag )oltages es graps graps.. -astly -astly## *art  of te experiment is te !ommon !olle!tor small signal amplier. Te base and te emitter are te input and output terminals# respe!ti)ely.

In order for a transistor to amplify a! signals# it must operate in te a!ti)e !ondit !ondition ion.. Tis Tis is done done by for$ar for$ard d biasin biasing g te base'e base'emi mitte tterr /un!ti /un!tion on and re)erse biasing te base'!olle!tor /un!tion. As performed in te experiment# te "0 operation $as done rst before applying a! signal to ensure tat tere $ill be an ampli!ation.

 Te )oltage gain des!ribes o$ mu! ampli!ation is done to te input

a! )oltage. It is te ratio of te output a! )oltage to te input a! )oltage. In te

experiment#

ea! small'signal amplier !ir!uit arrangement

$as

analysed in order to see $i! one produ!es te most )oltage gain and $i! one demonstrates pase re)ersal.

ased on te results of te experiment te !ommon base amplier a!ie)ed te igest )alue of )oltage gain and te !ommon !olle!tor for te lo$est. Tis des!ribes and explains to us tat te !ommon base small signal amplier is te best amplier $en it !omes to )oltage# and te !ommon !olle!tor is te $orst. Te !ommon emitter o$e)er is in bet$een tem. Also# te !ommon emitter $as te one obser)ed tat demonstrates pase re)ersal.  Te pase sift from input to output is 123 degrees# $i! is /ust anoter $ay of saying te signal is 4ipped in polarity. 5at te pase sift means is tat as te input starts going positi)e# te output starts going negati)e.  Te pase sift is due to o$ te de)i!e $orks in tat !onguration. 5en te )oltage on te input starts to go positi)e# te de)i!e is for$ard biased e)en more tan it $as at idle. As for$ard bias in!reases# !olle!tor !urrent in!reases. Tat6s o$ te de)i!e $orks. Turn it on more# and more !urrent 4o$s troug it. As !olle!tor !urrent in!reases# !olle!tor )oltage

de!reases. Tere6s

te

key.

In!reasing base )oltage

!auses

in!reasing !olle!tor !urrent and de!reases !olle!tor )oltage. In!reasing base )oltage !auses de!reasing !olle!tor )oltage. And te opposite is true.

CONCLUSION:

I terefore !on!lude tat: o

An amplier is an ele!troni! !ir!uit !apable of in!reasing !urrent# )oltage and po$er.

o

A small'signal amplier is an amplier designed to andle small a! signals.

o

A small'signal amplier !an make use of tree !ir!uit arrangements namely te !ommon'base# !ommon'emitter and te !ommon'!olle!tor.

o

efore performing a! analysis to te amplier# one must ensure tat a !ertain !ir!uit arrangement !an really do perform ampli!ation.

o

Ampli!ation is done by for$ard biasing te base'emitter /un!tion and re)erse biasing te base'!olle!tor /un!tion during "0 analysis. 5it tese !onditions# $e !an ensure tat te !ir!uit is in a!ti)e !ondition and !an !ondu!t ampli!ation.

o

7oltage gain des!ribes o$ mu! ampli!ation is done to te input a! )oltage. It is te ratio of te output a! )oltage to te input a! )oltage.

o

 Te !ommon'base amplier pro)ides te most )oltage gain#

o

 Te !ommon'emitter $i! so$s a small gain.

o

 Te !ommon'!olle!tor amplier as an approximate )oltage gain tat is e8ual to one $i! means tat te )oltage at te input signal is e8ual to te )oltage at te output signal.

o

 Te only !ir!uit arrangement tat so$s pase re)ersal is te !ommon'emitter amplier.