![]() ![]() Finally we need to draw the plot between V CB and I C at constant I E. The below figure show the output characteristics of common base configuration. Repeat the same process at different I E values. First keep the emitter current constant and vary the V CB value for different points, now record the I C values at each point. The output characteristics of common base configuration are obtained between output current and output voltage with constant input current. R in = V EB / I E (when V CB is constant) The equation to calculate the input resistance R in value is given below. The below figure show the input characteristics of common base configuration. Now with these values we need to plot the graph between I E and V EB parameters. Repeat the same process at different output voltage levels. ![]() First keep the output voltage V CB constant and vary the input voltage V EB for different points then at each point record the input current I E value. Input characteristics are obtained between input current and input voltage with constant output voltage. The common base transistor circuit is given below. The common base circuit is mainly used in single stage amplifier circuits, such as microphone pre amplifier or radio frequency amplifiers because of their high frequency response. The voltage gain for this configuration of circuit is given below.Ī V = V out/V in = (I C*R L) / (I E*R in)Ĭurrent gain in common base configuration is given as ratio of output resistance to input resistance is high. This type of configuration has high resistance gain i.e. This transistor configuration has high output impedance and low input impedance. The input characteristics of this configuration are looks like characteristics of illuminated photo diode while the output characteristics represents a forward biased diode. The construction of this configuration circuit is difficult because this type has high voltage gain values. The amplifier circuit configuration of this type is called as non-inverting amplifier circuit. The input and output signals are in-phase in this configuration. The current gain is generally equal or less than to unity for this type of configuration. The input current flowing into the emitter terminal must be higher than the base current and collector current to operate the transistor, therefore the output collector current is less than the input emitter current. Here the input parameters are V EB and I E and the output parameters are V CB and I C. Here the input is applied between the base and emitter terminals and the corresponding output signal is taken between the base and collector terminals with the base terminal grounded. The configuration name itself indicates the common terminal. In this configuration we use base as common terminal for both input and output signals. Now we discuss about these three different configurations of transistors with their input and output characteristics in the below sections. Common Emitter (CE) Configuration: current gain and voltage gain.Common Collector (CC) Configuration: current gain but no voltage gain.Common Base (CB) Configuration: no current gain but voltage gain.The behavior of these three different configurations of transistors with respect to gain is given below. ![]() Generally there are three different configurations of transistors and they are common base (CB) configuration, common collector (CC) configuration and common emitter (CE) configuration. Using this property we construct the circuits and these structures are called transistor configurations. To overcome these problems we use one terminal as common for both input and output actions. But in the circuit connections we need four terminals, two terminals for input and another two terminals for output. We know that generally the transistor has three terminals – emitter (E), base (B) and collector. ![]()
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