10.7(b) the emitter-base junction of P-N-P transistor is forward biased by connecting the positive terminal of battery V EB to the emitter and negative terminal to the base while collector-base junction is reverse biased by connecting the negative terminal of battery V CB to the collector and positive terminal to the base. 10.7(a), the emitter-base junction of N-P-N transistor is forward biased by connecting the negative terminal of battery V EB to the emitter and positive terminal to the base while collector-base junction is reverse biased by connecting the positive terminal of the battery V CB to the collector and negative terminal to the base. For this purpose a battery V EB is connected between emitter and base while a battery V CB is connected between the collector and base, as shown in Fig. This type of Transistor Biasing is known as FR biasing. Forward-Reverse Biasing: As already mentioned, for normal operation of a transistor emitter-base junction is always forward biased and collector-base junction is always reverse biased. Accordingly it may operate in different conditions as listed in Table 10.1.ġ. Different Operating Conditions For a Transistor:Ī transistor has two junctions (emitter-base and collector-base junctions), and each of these two junctions, may be forward biased or reverse biased, therefore, there are four possible ways of Transistor Biasing these two junctions. This is precisely what happens in a transistor. No emitter current means almost no collector current. Thus the magnitude of collector current l C depends upon the magnitude of emitter current I E. However, if the emitter-base junction is forward biased and the collector-base junction is reverse biased it is seen that almost whole (about 95%) of the current constituted by the emitter flows through collector circuit. Now if the Transistor Biasing of collector-base junction is ignored and only emitter-base junction, which is forward biased is considered then practically whole of the emitter current flows through the base i.e., I B = I E.
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