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Transistor=Transfer+Resistor. When Transistor operates in active region its input resistance is high and output resistance is low. So,We can consider transistor as a device which transfers its resistance from high to low. And by this property transistor amplifies input signal.
a transistor can only work in active region cox in active region collector base junction is in reverse bias and emitter base junction is in forward bias.
No
transistor size depends on its channel length, that is the length of the region in which a transistor act as an electron tube. the shorter the region, the lowest the resistance, the fastest the transistor, etc... so, it is always good to scale transistor size. problem is that you have to apply a 'good' electrical field in the channel, in order to drive a good 'ON' or 'OFF' state for your transistor. that's why it's not easy to scale their size.
For switching applications transistor is biased to operate in the saturation or cutoff region. Transistor in cutoff region will act as an open switching whereas in saturation will act as a closed switch.
holes are majority in base
The active region of a transistor is when the transistor has sufficient base current to turn the transistor on and for a larger current to flow from emitter to collector. This is the region where the transistor is on and fully operating.
FOR n-type semiconductor the majority charge carrier is electron and for n-type semiconductor it is hole. the majority and minority charge carrier is result of free electron and hole. the majority charge carrier is responsible for transport of electron.
Transistor=Transfer+Resistor. When Transistor operates in active region its input resistance is high and output resistance is low. So,We can consider transistor as a device which transfers its resistance from high to low. And by this property transistor amplifies input signal.
The width of the base is very thin to increase the majority carrier concentration gradient in the base region thereby enhancing the diffusion current and also to reduce the number of majority carriers lost due to recombination in the base.
a transistor in active region when emitter junction is forward biased nd collector junction is reverse biased
The cutoff region is when the transistor doesn't have sufficient base current to drive a larger current from emitter to collector. Therefore, the transistor does not turn on and stays shut off.
depletion layer depletion zone juntion region space charge region bipolar transistor field effect transistor variable capacitance diode
a transistor can only work in active region cox in active region collector base junction is in reverse bias and emitter base junction is in forward bias.
The output current of a transistor is controlled by the current in the 'base' input: Increasing the control current will increase the output current in a more or less linear fashion. In the saturation region, this is no longer true: The transistor is nearing the limits of how much current it can conduct, so increasing the control current further has little or no effect. When using a transistor as an amplifier, you want to stay away from the saturation region as it would distort the signal you are amplifying. When using a transistor as an on/off switch, as in digital circuits, being in the saturated region is 'on' and a normal mode of operation.
The breakdown region of a transistor is the region where the supply voltage, Vcc, becomes so large that the collector-emitter junction of the transistor breaks down and conducts, even though there is no base current.
Collector has larger area than base and emitter because base collector is reverse biased, hence the current flow here due to the minority carriers and the large power dissipation takes place by the majority carriers, this power dissipated in the form of heat.. To cool the device from heat we made the larger area........