Experimental Determination of Hybrid Parameters: Determination of hybrid parameters of a general linear circuit has already been discussed. For determination of hybrid parameters for a CE transistor, consider the circuits given in Fig. 11.8. The rms values will be considered in discussion. Volt-ampere equations for a CE transistor are as given below : For measurement […]
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Transistor Hybrid Model: The basic assumption in arriving at a transistor linear model or equivalent circuit is that the variations about the operating or quiescent point are small and, therefore, the transistor parameters can be considered constant over the small range of operation. Many transistor models have been proposed, each one having its particular merits
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Hybrid Parameters of Transistor or h Parameters and Hybrid Model: A box representing a two-port network is illustrated in Fig. 11.1. The terminal behavior of a two-port device may be specified by two voltages and two currents (voltage v1, and current ii at the input port and voltage v2 and current i2 at the output
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Leakage Current in a Transistor and Breakdown Voltage: Leakage Currents: In CB circuits shown in Fig. 10.77, if emitter current is made zero, the B-C junction still remains reverse biased and therefore, a reverse-bias leakage current exists in this junction, and this current corresponds to the reverse-bias saturation current in a diode. The direction of
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What is BJT Beta Rule? Like transfer of primary and secondary winding impedances of a transformer, resistance from one part of a transistor circuit can be referred to another parts. For instance, resistance of collector circuit, RL can be referred to the base circuit and vice versa. Similarly resistance of emitter circuit RE may be
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DC Equivalent Circuit of Transistor: DC Equivalent Circuit of Transistor – In the common base circuit, the emitter diode acts like a forward biased ideal diode, while collector diode acts as a current source because of transistor action. Thus an ideal transistor in common-base configuration can be considered as a rectifier diode in the emitter
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Transistor approximation (Ideal, Second and Higher): An NPN transistor is shown in Fig. 10.71 (a). Voltage appearing across the emitter diode is denoted by VBE and that appearing across the collector-emitter terminals is denoted by VCE. Ideal Approximation: An ideal approximation of a transistor is shown in Fig. 10.71 (b). Emitter diode is visualized as
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What is Thermal Runaway and Heat Sink? The maximum average power PC max which a transistor can dissipate depends upon the construction of the transistor and may lie in the range of a few milliwatts and 200 W. This maximum power is limited by the temperature that the collector-base junction withstand. For silicon transistor this
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How to use a Transistor as a Diode – Working and Equation: The transistor can be modified to operate as a diode by short circuiting the two transistor terminals, as shown in Fig. 10.69 [collector and base terminals are shorted making VCB = 0] and for a practical P-N junction if voltage across it is less
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Transistor Lead Identification and Testing: Transistor Lead Identification and Testing – After the transistor has been manufactured, as already discussed, leads of, typically, gold, aluminium, or nickel are then attached and the entire structure is encapsulated in a container such as that given in Fig. 10.65. Those with the studs and heat sinks are high
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