HI ANURAGMASH
> ALTHOUGH THERE IS NO DIFFERENCE IN THE BASIC OPERATION OF TRANSISTORS IN ANY MODE i>e INTERNALLY IF YOU LEARN THE MICROELECTRONIC DETAILS.
> NOW THE ONLY DIFFERENCE COMES THAT WHAT IS APPLIED AT THE INPUT AND WHAT IS THE OUTPUT.
TREAT THE TRANSISTORS AS CURRENT CONTROLLED DEVICES ALTHOUGH THEY CAN BE CONTROLLED BY THE VOLTAGE ALSO(ACTUALLY THIS IS A DOUBT FOR
ME TOO AS WHY THEY ARE TREATED AS CURRENT CONTROLLED AND NOT VOLTAGE CONTROLLED BESIDES HISTORICAL REASONS)
OK
COMMON BASE CONFIGURATION: INPUT IS Ie (EMITTER CURRENT) AND OUTPUT IS TE Ic (COLLECTOR CURRENT) . LOOK THE CURRENT GAIN i.e ALPHA(APPROX
UNITY). IF YOU LOOK AT THE VOLTAGE GAIN, IT WILL BE QUIET HIGH say 120 for ex.
SO POWER GAIN = 120 (APPROX)
COMMON EMITTER CONFIGURATION : I/P IS Ib (BASE CURRENT) AND O/P IS Ic (COLLECTOR CURRENT). CURRENT GAIN IS BETA SAY LOW VALUES OF AROUND 20
()WORST CASE) for ex AND THE VOLTAGE GAIN SAY AROUND 50 for ex.
SO POWER GAIN = 1000
SO ONE OF THE DIFFERENCE COMES IN THE GAINS SCENARIO DEPENDING UPON WHAT IS THE I/P AND O/P. THE INTERNAL FLOW OF CARRIERS IS ESSENTIALLY THE SAME IN ALL CONFIGs AND SAME SEMICONDUCTOR PHYSICS IS APPLICABLE INSIDE THE TRANSISTOR IN ANY CONFIGs. WHENEVER WE HAVE TO USE THE TRANSISTOR IN ACTIVE MODE , WE WILL ALWAYS FWD BIAS THE EMITTER JUNCTION AND REVERSE BIAS THE COLLECTOR JUNCTION.
OF COURSE THE OTHER DIFFERENCES LIE IN THE I/P , O/P IMPEDENCES AND O/P SIGNAL POLARITY w.r.t THE I/P SIGNAL . INTERNALLY YOU HAVEN'T CHANGED ANYTHING , SO THE TRANSISTOR WILL WORK AS IT WORKS IN THE CB CONFIG. WHICH YOU MIGHT HAVE STUDIED AT FIRST. THE ONLY CHANGE YOU MAKE IS IN THE OUTER CONFIGURATION , THE I/Ps AND THE O/Ps SO THAT THE CHARACTERISTICS CURVES ARE DISSIMILAR. WE CAN USE THE SAME TRANSISTOR FOR DIFFERENT CONFIGURATIONS BY CHANGING THE OUTER CONFIG.
>I DON'T KNOW OF THIS FACT THAT THE COMMON TERMINAL CURRENT HELPS IN CONTROLLING THE OTHER TWO CURRENTS. AS FAR AS I HAVE KNOWN TILL NOW, IT'S THE DOPING PROFILES, THE GEOMETRICAL SIZES, AND V OR I SOURCES THAT ARE APPLIED TO CONTROL THE FLOW OF ANY CURRENT WITHIN THE TRANSISTOR. SINCE ALWAYS Ie=Ib + Ic . AFFECTING ANY CURRENT WOULD EFFECT THE OTHER TWO NATURALLY BUT I THINK WHAT YOU MEAN IS THAT CONTROL OF Ib. THE BASE DOIPNG OR THE EFFECTIVE BASE WIDTH CONTROL BY REVERSE BIAS CAN CONTROL Ib.
>GROUND MEANS NOTHING EXCEPT TO MAKE THE POTENTIAL ZERO AND PRACTICALLY WE DO SO BY DEPOSITING LARGE COPPER BASE WHERE GND IS REQUIRED AS GND MEANS THAT IT HAS INFINITE CHARGE CARRIERS AND HUGE METAL DEPOSITS DO HAVE electrons IN ABUNDANCE JUST LIKE THE EARTH GND HAS INFINITE CHARGE.
I hope you know that capital letters are the equivalent of shouting. You can use lower case font like the rest of us [alexan_e]