At first glance, this looks like an insulator but the actual behavior is far more interesting, if we apply external voltages properly n n p collector emitter base moderately doped. Common collector configuration physics and radioelectronics. The frequency response will be measured and the dc voltages will be. Input characteristics of common collector circuit is a curve between input current here base current ib and input voltage here basecollector voltage vcb at constant emittercollector voltage vec. The first highfrequency transistor was the surfacebarrier germanium transistor developed by philco in 1953, capable of operating up to 60 mhz. The product has constant h fe characteristics in a wide current range, providing highquality audio sounds. Common base cb transistor gives high current gain but low voltage gain. Commoncollector configuration of a transistor topics covered.
The common collector transistor circuit configuration gains its name from the fact that the collector circuit is common to both input and output circuits, the base being associated with only the input, then the emitter with the output only. Transistor emitter follower, common collector amplifier. The common collector amplifier has high input impedance and low output impedance. An npn transistor has an n type emitter, a p type base and an n type collector while a pnp transistor. Dc solution a replace the capacitors with open circuits. The objective of this experiment is to explore the basic applications of the bipolar junction transistor bjt. Common collector configuration of transistor detailed. Transistors characteristics for cb, ce and cc transistors. Description the 2sc3519 is an npn transistor of 160 v, 15 a. Figure 98 shows collector curves for different values of base current. It is also often more convenient to use a discrete transistor for an individual circuit within a larger system, for which ics are not readily available. Transistor characteristics are the plots which represent the relationships between the current and the voltages of a transistor in a particular configuration. Transistors characteristics are graphs of the various currents ibis current into the base, ie is current out of the emitter, and icis current into collector and voltages. The other name for the common collector is emitter follower.
This device can also be used in power switching circuits such as relay or solenoid drivers, dc. When i b 0 a, the transistor is in its cutoff region, and only a small leakage current flows as i c. A simple circuit for measuring transistor characteristics as we said, bipolar transistors have three terminals. When the transistor saturates and collector voltage approaches emitter voltage, collector voltage goes below ground and changes polarity. The output characteristic of the commonbase stage is a horizontal line the first attached picture. The curve obtains between the base current i b and the collector base voltage v cb at constant collector emitter voltage v ec shows the input characteristics. The curve describes the changes in the values of input current with the variation in the values of input voltage keeping the output voltage constant. Common emitter transistor configuration, characteristics. Silicon npn epitaxial planar transistor 2sc3519 data sheet 2sc3519dse rev. Transistors now that we know about diodes, lets put two of them together, as follows. In ce transistor it gives high current gain and high voltage gain. The bipolar transistor basic construction consists of two pnjunctions producing three connecting terminals with each terminal being given a name to identify it from the other two. This is the main reason for use in a most amplifying circuit. These were made by etching depressions into an ntype germanium base from both sides with jets of indiumiii sulfate until it was a few tenthousandths of an inch thick.
By considering the transistor configuration circuits to be analogous to twoport networks, they can be analyzed using the characteristiccurves which can be of the following types. If v ce increases too much, the transistor goes into the breakdown region. Indium electroplated into the depressions formed the collector and emitter. In a common emitter circuit you only have one power supply and the emitter is connected to ground, so collector voltage cannot go below ground. A common base and a common collector amplifier will be designed and tested. In another side, common collector cc transistor gives high voltage gain but low current gain. Bjt characteristics theory the transistor is a two junction, three terminal semiconductor device which has three regions namely the emitter region, the base region, and the collector region. Any twoport network which is analogous to transistor configuration circuits can be analysed using three types of characteristic curves. The object is to solve for the smallsignal voltage gain, input resistance, and output resistance. Three terminals of transistor are emittere, baseb, and collector c.
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