Which of the transistor currents is always the largest? Which is always the smallest? Which two currents are relatively close in magnitude? The emitter current IE is always the largest one. The base current IB is always the smallest. The collector current IC and emitter current IE are relatively close in magnitude. Why silicon type transistors are more often used than germanium type?
Because silicon transistor has smaller cut-off current ICBO, small variations in ICBO due to variations in temperature and high operating temperature as compared to those in case of germanium type. Why collector is made larger than emitter and base? Collector is made physically larger than emitter and base because collector is to dissipate much power. Why the width of the base region of a transistor is kept very small compared to other regions?
Base region of a transistor is kept very small and very lightly doped so as to pass most of the injected charge carriers to the collector. Why emitter is always forward biased? Emitter is always forward biased w. Why collector is always reverse-biased w. Collector is always reverse-biased w.
Can a transistor be obtained by connecting two semiconductor diodes back-to-back? Because in case of two discrete back-to-back connected diodes there are four doped regions instead of three and there is nothing that resembles a thin base region between an emitter and a collector.
Define beta of a transistor. Why is there a maximum limit of collector supply voltage for a transistor? Although collector current is practically independent of collector supply voltage over the transistor operating range, but if VCB is increase beyond a certain vale collector current IC is eventually increases rapidly and possibly destroys the device.
ICEO is given as :. Why CE configuration is most popular in amplifier circuits? CE configuration is mainly used because its current, voltage and power gains are quite high and the ratio of output impedance and input impedance are quite moderate.
Why CC configuration is called a voltage buffer? Explain what is other name? Because of its high input impedance and low output impedance, the common collector circuit finds wide application as a buffer amplifier between a high impedance source and low impedance load.
Its other name is emitter follower. Simply put, a BJT is a three-terminal semiconductor device. The name "bipolar" comes from the fact that this type of transistor contains two types of semiconductor material—one positive type p-type and one negative type n-type —through which a current flows. Bipolar junction transistors usually contain silicon. Moreover, impurities are commonly added to the silicon via doping to make the layers behave as desired. It's the p-type layers in a BJT's job to attract the electrons that enter the transistor through its input circuit.
The n-type layers, on the other hand, should encourage electrons to flow out of the transistor. This push-and-pull effect between the layers enables the electrical current to be amplified and controlled. The configuration of the layers in a BJT determines the electrical current's flow and ensures that a charge can't return in the same direction as it came.
This setup protects the system from overheating or becoming damaged. Bipolar junction transistor BJP workings. Source: Electronics Tutorials. When electrical contacts are placed on all three silicon layers and the current is switched on, the electrons in the current will flow between the n-type and p-type silicon layers. In an NPN sandwich, amplification occurs when a small positive current is attached to the p-type layer the base.
Here, one of the n-type layers the emitter is negatively charged, while the other the collector is positively charged. In an NPN Sandwich, electrons are attracted to the base from the emitter.
The electrons then move from the emitter to the collector; this movement creates a higher current flow between the two n-type layers. Invented by the physicist William Shockley in , the BJT has gone through a number of iterations over the years. Until the s, germanium was used in the layers.
Towards the end of the century, germanium was replaced by silicon, a material demonstrating more thermally stable.
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