The larger the β* value the larger the injected carriers across collector junction and hence collector current increases.Ħ. The larger the value of emitter injection efficiency, the larger the injected carriers at emitter junction and this increases the collector current. The ratio of collector current to base current is known as transport factor The ratio of current of injected carriers at emitter junction to the total emitter current is called the emitter junction efficiency. Explain what are ‘emitter injection efficiently’ and ‘base transport factor’ and how do they influence the transistor operation? with the change in transistor parameters or temperature rise, the operating point may shift and the amplifier output will be unstable.ĥ.produce distortion in the output signal.In case the transistor is not biased properly, it would : The amount of bias required is significant for the establishment of the operating or the Q-point which is dictated by the mode of operation desired. Discuss the need for biasing the transistor.įor normal operation, base-emitter junction should be forward biased and the collector-base junction reverse biased. ![]() Generally no arrow head is marked for collector since its reverse leakage current is always opposite to the direction of emitter current.Ĥ. The direction indicated the conventional direction of current flow( from emitter-to-base in case of p-n-p transistor and from base-to-emitter in case of n-p-n transistor). Explain what is the significance of the arrow-head in the transistor symbol?Īrrow head is always marked on the emitter. So it is called the current controlled device.ģ. The output voltage, current or power is controlled by the input current in a transistor. Why transistor is called current controlled device? Explain why an ordinary junction transistor is called bipolar?īecause the transistor operation is carried out by two types of charge carriers (majority and minority carriers), an ordinary transistor is called bipolar.Ģ. ![]() Specialized types are used for high voltage switches, for radio-frequency amplifiers, or for switching high currents.1. Bipolar transistors are still used for amplification of signals, switching, and in mixed-signal integrated circuits using BiCMOS. Hundreds of bipolar junction transistors can be made in one circuit at very low cost.īipolar transistor integrated circuits were the main active devices of a generation of mainframe and minicomputers, but most computer systems now use CMOS integrated circuits relying on field-effect transistors. ![]() ![]() Diffused transistors, along with other components, are elements of integrated circuits for analog and digital functions. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material.
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