![]() Therefore, the output resistance of the CE circuit is lower than that of the CB circuit. that if the output characteristic of the CB Circuit is horizontal, they have a noticeable slope of the CE circuit. It is the ratio of the change in collector-emitter voltage (ΔV CE) to the change in the collector current (ΔI C) at IB being constant i.e. Point voltage above the knee, I C is almost constant.The transistors always operate at in the region above the knee voltage. This value of V CE that collector currentįig. Then the collector current becomes almost constant and independent of V CE. I C collector current varies with V CE for V CE only from 0 to 1V.The following points can be noted from the characteristics: Following similar procedure, a family of output characteristics can be drawn as shown in Fig.(iii). The test can be repeated for I B = 10 ♚ to obtain the new output characteristic as shown in Fig.(ii). This gives the output characteristic at I B = 5 ♚ as shown in Fig.(i). Then plot the readings on a graph, taking I C along y-axis and V CE along x-axis. It is the curve between collector current I C and collector-emitter voltage V CE at constant base current I B.The output characteristics of a CE circuit can be drawn with the help of the circuit shown in Fig.Keeping the base current I B fixed at some value say, 5 ♚, note the collector current I C for various values of VCE. Since a very small V EB of is enough to make a large current of I E emitter current, the input resistance is quite low, on the order of a few ohms. In fact, the resistance input is the opposition provided to the current signal. It is the ratio of change in emitter base voltage (ΔV EB) to the resulting change in emitter current (ΔI E) at constant collector base voltage (V CB), Therefore, the input resistance of the CE circuit is higher than the resistance of the CB circuit. This is expected since the base-emitter section of transistor is a diode and it is forward biased.Ĭompared to the CB arrangement, I B increases less rapidly in V BE. ![]() The characteristic resembles that of a forward biased diode curve. This also provides an input Characteristics at V CE = 10V, as shown in fig.The following points may benoted from the characteristics :Īmong the characteristics, we can point out the following: Then build the display obtained in the graph to build I B along the Y axis, and build V BE along the Y axis along the x-axis. The input characteristics of the CE connection can be seen in the diagram shown in the figure.Save permanent VCE (SAY, 10V) and follow the default current I B for various V BE values. VBE is important when doing DC analysis of a transistor circuit because it is used for calculations to find the transistors DC values. For a germanium transistor (which is more rare), VBE is approximately 0.3V. VBE is approximately 0.7V for a silicon transistor. This is the curve between the base current of IB and the base-emitter voltage VBE with a constant collector-emitter voltage VCE. VBE is the voltage that falls between the base and emitter of a bipolar junction transistor. If we kept maintaining a reasonably high voltage on the collector, the collector current would continue growing with the base-emitter voltage, exponentially, until the transistor overheated and melted.The important characteristics of this circuit configuration are input characteristics and output Characteristics In a typical transistor circuit with a common emitter, there is a load, say, a resistor ($R_L$ on the diagram below), in the collector circuit.Īs the base-emitter voltage, $V_$), an increase of the voltage drop on the load leads to a decrease of the voltage on the collector and, at some point, it becomes too low to support the redirection of the electrons coming from the emitter to the base, after which the collector current will plateau. The big difference is that, in the transistor, the lion's share of the emitter current is redirected to the collector, as long as the voltage on the collector (say, relative to the emitter) is reasonably high. ![]() The base-emitter junction has most characteristics of a diode in a sense that the emitter current increases exponentially with the base-emitter voltage. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |