![]() The channel refers to the path for the flow of current. Based on its construction, FET has a channel between its drain and source. ![]() The three terminals of FET are Drain (D), Gate (G) and Source (S). the current flow only due to majority charge carriers that is either electrons or holes. Related Post : What is PNP Transistor? Construction, Working & ApplicationsįET or field-effect transistor is a type of transistor that uses the electric field or voltage to control the current flow.Therefore the total current I C is emitter current minus base current In the symbol of PNP transistor, the arrowhead pointing inwards represents the direction of the current flowing inside the emitter toward the base and collector. Since the majority carriers are holes, the recovery time of the PNP transistor is comparatively high thus it has low switching speed than the NPN transistor. PNP transistor switches on when negative voltage V BE is applied to the base region and switches off when a positive voltage is applied. Reverse biasing collector-emitter junction and forward biasing base-emitter junction puts the transistor into conduction mode where the output current is directly proportional to the base current. The majority charge carriers are holes while the minority charge carriers are electrons. The middle N-layer is called base while the surrounding two layers are called collector and emitter. The thin N-layer is sandwiched between two thick P-layers. The PNP transistor is formed by the combination of two P-layers and one N-layer. Related Post: What is NPN Transistor? Construction, Working & Applications PNP Transistor NPN transistor switches on by applying positive base-emitter voltage V BE and since the majority carriers are electrons, it has a high switching speed. The little arrow head pointing outwards of the emitter shows the current direction going outward of the emitter. The symbol of the NPN transistor also represents the direction of the current. While the total emitter current I E is the sum of both base I b and collector current I C. The current is directly proportional to the base current. Applying current I B to the base terminal allows current I C from the collector to the emitter. ![]() The majority charge carriers are electrons while the minority charge carriers are holes. The three terminals Collector, Base and Emitter each rise from N, P and N regions respectively. The P-region is sandwiched between N-regions. NPN Transistor is formed by the combination of two N-type materials and one P-type material. Related Post: Bipolar Junction Transistor (BJT) – Construction, Working, Types & Applications.The output impedance is very high due to collector-emitter reverse bias. Since its base-emitter junction or input is forward biased, the input impedance is very low. This current is directly proportional to the base current. By connecting the base-collector junction in reverse and base-emitter junction in forward bias allows the flow of current between emitter and collector. It means it uses the input current at its base terminal to control the output current or collector current. The emitter and collector are both heavily doped with the emitter comparatively heavily doped than the collector.īJT is a current controlled device. The base is the most lightly doped layer of all. The base is the middle layer sandwiched between Emitter and Collector. This is because the transistor transfers its resistance from one end to another end based on the input signal.Ī transistor is mainly classified into two types: The word “ Transistor” is the combination of two words “Trans” for “ Transfer” and “istor” for “ Res istor”. A small current or voltage at its input can be used to control very high output voltage or current. Heterojunction Bipolar Transistor (HBT)Ī transistor is a three-terminal semiconductor device that is used for the switching or amplification of a signal.
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