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The name transistor comes from transferring an electrical signal across a resistor
A transistor is a three-terminal semiconductor device that can perform two functions that are needed to design an electronic circuits as (amplification and switching )
transistor switch is a device for controlling a relatively large current between or voltage across two terminals by means of a small control current or voltage applied at a third terminal.
amplification consists of magnifying a signal by transferring energy to it from an external source
The Field Effect Transistor(FET)
| The bipolar Junction Transistor (BJT)
| is an active device(gate , drain , source)it is a voltage controlled valve.The gate voltage VGS controls the drain current (1D).
| is an active deviceis a three-element (emitter, base, and collector )it is a current control value.The base current Ib control the collector current (Ic) '
Regions of BJT operation
| The active
| The saturation
| The breakdown
| The transistor is off there is no conduction between the collector and emitterboth junctions are reverse biased the base current is very small, no current flows collector. ( IB ≈ 0 ) ( IC = 0)
| The transistor is onthe transistor can act as a linear amplifier where the BE junction isforward biased and the CB junction is reverse biased. In this region the collector current is controlled by the base current ( IC = β IB)
| The transistor is onthe transistor can act as a switch, where both junctions are forward biased. the collector current varies very little with a change in the base current. The VCE is small, a few tenths of volt. The collector current is dependent on VCE unlike in the active region
| The transistor Is damageThat determines the physical limit of operation of the device.
BJT is formed by doping ( Joining ) three sections of...
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