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Transistor - Coggle Diagram
Transistor
A device that has three terminals. :
base
has the smallest area amongst the two regions
lightly doped
emitter
heavily doped
has an area larger than the base but larger than the emitter
collector
moderately doped
has the largest area amongst the two regions
applications
transistor as an amplifier
amplifies the voltage
working
the DC bias voltage applied to the emitter base junction , makes it remain in forward biased conductor
the forward biased is maintained regardless of the polarity of the signals
the low resistance in input circuit , lets any small change in input signal to result in an appreciable change in the output
the emitter current caused by the input signal contributes the collector current which then flows through the load resistor R. results in the large voltage drop across it.
thus a small input voltage results in a large output voltage, which shows that the transistor works as an amplifier
transistor as a switch
current gain B + Ic/Ib
beta does not have units
there is a fixed beta value for each transistor
two types of bipolar junction transmitter (BJT) transistors
P-N-P transistor
collector and emitter while the base is negative
N-Type material is sandwiched between two P- Type material
it has holes in majority
if the base is at a lower voltage than emitter, current flows from front emitter to collector
N-P-N transistor
collector and emitter are negative while the base is positive
if the base is at a higher voltage than emitter , current flows from collector to emitter
it has lesser holes due to thin area and lighter doping
collector has electrons moderately doped
since there are few holes in base, some electrons move to B and the rest are attracted by the positive terminal of voc have greater potential move from base to collector to icl
It works as an amplifier
has three semi conductors and two NP junctions
normally, for normal operation of transistors the base emitter junction is forward based