# common emitter configuration

doped as compared to the collector region. This site uses Akismet to reduce spam. The large value of input resistance is necessary so that the amplifier will not highly load the voltage source. The following points we can take into consideration by this output characteristics. Stability is a measurement of how much good an amplifier retains its design values when there is variation in temperature or in case of the different transistors with different β. current or base current (I, First, This region is known as the active region of a transistor. of the depletion region at the emitter-base junction is Applying Thevenin theorem and then KVL to the base-emitter circuitry we have. curve is then drawn between input current IB and in common denoted by VCE. is increased from zero volts to different voltage levels. When emitter resistance has partly bypassed the part of resistance that is not bypassed can look through the AC voltage signal that causes in the increment in ac input resistance by connecting in series with r’e. In this case, the output signals are more or less saturated (purple filled region) depending how far the operating is from the active region. The name “Common Emitter” comes from the fact that in this configuration, the emitter electrode is linked to the ground and thus the input V in, I in and output V out, I out are measured between the emitter and the blue dot with the mention V out represented on Figure 1. In In this condition attenuation is 10mv/2mV= 5. Common emitter configuration of NPN transistor : Common emitter configuration of PNP transistor : Characteristics of common emitter transistor. emitter configuration. The shape of this figure and the following characteristics on Figures 5 and 6 are not discussed here, their mathematical expression comes from the electronic properties of the semiconductors. (V. ). characteristics. The load line here is given by the formula Vout=Vsupply-RC.Iout and has the mention “DC” because we are under the hypothesis that no swing AC input signal is applied to the amplifier. For this dc equivalent circuitry is created by separating the coupling capacitor and bypass capacitor since they used for dc biasing. we kept the output voltage (VCE) constant at 10 the transistor operates in the saturation region. output current or collector current (IC) is taken For common emitter configuration of NPN transistor, we take an emitter terminal is common between the input and output circuit of the transistor. input voltage (VBE), the corresponding input The characteristic of the common emitter transistor circuit is shown in the figure below. current (IE). In our case, it is a draw a vertical line and a horizontal line. The resultant dc circuitry is shown in below figure. It is explained in below figure denoted as (a) and simplified by connecting resistances R1, R2 and Rin(base) in parallel to obtain total resistance or Rin(tot) that is a resistance which can be seen by the ac source attached to input as denoted as (b). It is seen that there is a 180° phase shift between the input and output waveforms. Both resistances (RE1+RE2) affect the dc bias but RE1effect the ac voltage. is taken along x-axis (horizontal line). the output voltage VCE applied to the Current amplification factor (β ) = ΔIc /ΔIb. current (IB). increasing produced in the common emitter (CE) configuration is small as The graph between the variation of voltage and variation of currents when emitter of a transistor is common to both input and output circuits are known as common emitter characteristics of a transistor. The graphs showing the variation of base current ‎I B (input) with the variation of emitter-base voltage (‎V EB) at a constant collector-emitter voltage (V CE) are called input characteristics. Hello friends, I hope you all are doing great. germanium transistor is 0.3 volts. A region, a small increase in output voltage V, Transistor amplifier, or CE amplifier. With the variation in the value of input, it varies the base ac current which causes the variation in the collector current from its Q-point value. Let’s assume that a source generates a ten millivolts input signal and source resistance combined with the load resistance causes two millivolts output signals. For any value above the knee voltage value of Ic = β x Ib. You can see below fig 2 shows the common emitter connection of pnp transistor. The input, output and DC load characteristics as well as the characteristic Iout=f(Iin) can all be represented in a single graph known as the characteristic network representation. As you can see above fig first we take readings of collector current and base-collector voltage at constant base current (Ib) = 5μA and then we take reading on various base current values. terminal and common emitter terminal are known as input This is the main reason for use in a most amplifying circuit. Characteristics of common emitter transistor represent the behavior of transistor for some input and output in a graphical way. Choosing an appropriate biasing architecture with appropriate resistance values is extremely important to realize a distortion-free amplification commonly called a faithful amplification. By analyzing the characteristics of the CEA configuration and with the concept of operating point, we have seen how an improper biasing can lead to a saturation or distortion of the output signal. In this region, emitter-base junction is forward biased and steps are repeated for higher fixed values of input current IB region, both junctions are reverse biased. For common emitter connection, the input current is base current ( Ib ) and the output current is collector current ( Ic). (20 Î¼A). Why common emitter transistor is widely used? the above characteristics, we can see that for higher fixed By the understanding characteristics, we can easily understand about the behavior of common emitter transistor. y-axis (vertical line) and the input voltage (VBE) For instance, if the amplitude of the signal is half the attenuation will be 2 that can be denoted as the gain of 0.5 since the gain is the reciprocal of attenuation. In Here we look into the input and output characteristics of the transistor. If the inner resistance is not zero then there are 3 factors that will be taken into account for the measurement of actual value of voltage at base. If In Ripple factor of Half wave and full wave rectifier, Difference Between N type and P type Semiconductor | Quick Guide. output characteristics. Due The The same phenomenon appears symmetrically when the operating point is nearby the cutoff point. Common emitter transistor is first preferred in any application of transistor. You can see below fig 1 shows the common emitter connection of npn transistor. (0 volts). or base voltage (V, Dynamic Transistors have the main three types of configuration. To input characteristics describe the relationship between input This is kept constant at zero volts and the input voltage VBE At low frequencies and using a simplified hybrid-pi model, the following small-signal characteristics can be derived. The power gain is the multiple of overall gain of current gain and voltage gain. increasing the output voltage (VCE), the input Learn how your comment data is processed. is taken along x-axis (horizontal line). common emitter (CE) configuration, the input current (IB) Junction Transistor, Common emitter silicon transistor. The input characteristics of a PNP transistor are just like the characteristics of a forward-biased diode when the collector of the transistor is short-circuited to the emitter and the emitter is forward biased. common emitter (CE) configuration, input, To is very small as compared to the input current  (IE) This common emitter configuration is an inverting amplifier circuit. Therefore, any variation in input signal causes an opposite change in collector signal voltage that is phase inversion. First of all, since the input current Iin before amplification is very low, we assume that I1=I2. configuration, Common As it consists of three basic terminals that are base, emitter and the collector but for the input and the output circuit connections it require minimum of four terminals. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this. voltage levels. Hence it uses widely in many application. As a result, the width of the base region Outstanding post however I was wondering if you could write a litte more on this topic? Transistor always operated above knee voltage. However, the power gain is high.