![]() The I/p Characteristic is plotted at a constant O/p vtg. For common base (CB) configuration input current is the emitter current (IE) & I/p vtg. Input Characteristic: is always a graph of input current verses input vtg. Characteristics of a transistors in a common base configuration:-Ī.Larger the thickness of the base region smaller the value of the d.d.c three leads of a bipolar transistor are called the Emitter, Base, and Collector. A transistor is a semiconductor device, so the. Base Bias Collector-feedback bias Emitter-bias Voltage divider bias. ![]() We will discuss functions of these three terminals in the working of the transistor. The three terminals have specific names that are as follows:. Typically the value of d.d.c ranges between the 0.95 to 0.995 depending upon the thickness of the base region. The transistor formed in the former case will be NPN transistor and that formed in the latter case is PNP transistor. The value of the ddc for CB configuration will always be less than 1.This is because Current amplification factor or current gain (ddc):-Ĭurrent amplification factor or current gain is the ratio of collector current due to the injection to the total emitter current It doubles its value for every 100c rise in temperature. Since the I CBO flow’s due to terminally generated minority carrier’s it increases with increase the temperature. This is the reason transistor exhibit current gain.The collector current is much larger than the base current.This forms the collector electrons current. The electrons now move through the collector region, out through the collector lead into the +ve terminal of the collector vtg source.The BC depletion region diffuse e is being pulled across the reverse biased BC junction by the attraction of the collector supply vtg.Most of the e flowing from the emitter into the thin lightly dooped base region do not recombine but diffuse into the BC depletion region.The relatively few recombined flow out of the base lead as valance electrons, forming as small base current.When a transistor is saturated the collector-emitter voltage VCE is reduced to almost 0V. Those only a small percentage of all the e-flowing the BE junction can combine with the available holes in the base. The small base current controls the larger collector current.The base region is lightly doped & very thin so that it has a very limited number of holes.The heavily doped N-TYPE emitter region is full with conduction band(frep) electron’s that easily diffuse through the forward biased BE junction into the p-type base region where they become minority carrier’s same as forward biased diode region.The forward bias from base to emitter narrow’s the BE depletion region and the reverse bias from base to collector widens the BC depletion region shown in figure. As from above figure consider n-p-n transistor.The specification is met when at the specified value of IB, VB is greater than or equal to the specified minimum. The display shows the applied VB on the horizontal axis, and the resulting IB on the vertical axis. The collector is held open, and IB is sensed at the base terminal. On the curve tracer, VB is applied by the Collector Supply. Since it's the reverse current across a junction, IB exhibits a knee shaped rise, increasing rapidly once breakdown occurs. The saturation voltage is also a function of junction temperature. It is specified at a given collector current and a given base current or as a gain that is the ratio of collector current to base current. Emitter-Base Breakdown Voltage - V(br)EBOĮmitter-base breakdown voltage is the VB at which a specified IB flows, with the collector open. The collector-emitter saturation voltage is the voltage drop that occurs when the transistor is carrying current.
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