Hence the value of β falls.Īnd result on faithful amplification the transistor biasing can achieve with a bias battery or associating a circuit with a transistor. So this decreases the collector current (I C) while base current (I B) increases. When V CE is too low the collector base junction is not properly reverse biased. Proper minimum collector emitter voltage (V CE)įor faithful amplification V CE should not fall below 0.5 volt germanium transistor and 1 volt for silicon transistor. This will result in unfaithful amplification. If base emitter voltage V BE falls below these values during any part of the signal, that part will be amplified two lesser extent due to small collector current. The value of potential barrier is 0.7 volt for silicon and once the potential barrier overcome the base current and hence collector current increases sharply. Proper minimum base-emitter voltage (V BE) The value of zero signal collector current must be at least equal to the maximum collector current due to the signal alone.Ģ. If we introduce a battery source in the base circuit and no signal is applied a DC current I C will flow in the collector circuit due to the battery, this is known as zero signal collector current I C. In other words, the fulfilment of these conditions will ensure that transistor operates between the active region of the output characteristics i.e. On the other hand, condition (3) ensure that base-collector junction shall remain properly reverse biased at all times. The condition (1) and (2) ensure that base-emitter junction shall remain properly forward biased during all parts of the signal. Minimum proper collector emitter voltage at any instant.Minimum proper base emitter voltage at any instant.To achieve faithful amplification the following basic condition most be satisfy : ![]() ![]() The theory of a transistor suggests that it will function properly if its input circuit (that is base-emitter junction) is forward biased and the output circuit (that is collector-base junction) is reverse biased at all times. The basic purpose of biasing is to keep the base emitter junction forward biased and collector base junction is reverse biased, during the application of signal.ĭuring amplification the magnitude of signal should increase and there should be no change in signal shape, this increase in magnitude of the signal without any change in shape is known as faithful amplification. Transistor biasing is required for proper operation of transistors in any circuit.
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