 of DCSIP analysis of bipolar junction transistor in common emitter configuration in LT SPICE. Learning outcome of the session. In this session, we are going to simulate the DCSIP analysis of bipolar junction transistor in common emitter configuration. So, before proceeding to the session, let me ask you one question. What are the applications of the transistor? You may pause the video, think about the question and write down your answer in your notebook. You can resume the video by writing your answer in your notebook. Now, let me give you the answer. The mobile phone, industrial control, television, radio transistors are the best example of the applications of the transistor. Let us see the characteristics of common emitter configuration of the bipolar junction transistor. As you can see from the diagram, the bipolar junction transistor in this case used is the NPN where the base of the transistor is connected to the positive terminal of the supply voltage VBE and the emitter is connected to the negative terminal of the supply voltage VBE. So, this section that is the base to emitter region will act as the input region. The base current is denoted by the IB and the emitter current is denoted by the IE. Now, the collector of the transistor is connected to the positive terminal of the battery VCE and the negative terminal of the battery VCE is connected to the emitter of the transistor. Now in this case, you can observe that the emitter is common. That is, it is connected to the negative terminal of the battery VBE. Also, it is connected to the negative terminal of the battery VCE. That is why this configuration is called as a common emitter configuration. So, the common emitter configuration has the medium input and the output impedance level. So, because of that the current gain and the voltage gain of the common emitter configuration is medium. However, the power gain is high. So, what are the input characteristics of the common emitter configuration? The input characteristics is nothing, but the plot of the base emitter voltage VBE versus the base current IB. By keeping the collector to emitter voltage VCE at a VCE at the constant value. So, initially the voltage VCE is kept at the 0 volt. So, the curve looks similarly to the characteristics of the diode. As you can observe that after the 0.7 volt the current base current IB suddenly increases. So, when the output voltage VCE is at the 0 volt the emitter to base junction is further biased by the input voltage VBE. The emitter base junction will act like a normal PN junction diode. So, the small increase in the input voltage VBE will increase input current IB. So, output characteristics is nothing, but the plot of the output voltage VCE versus the output current IC. IC is the collector current. So, when the base current is 0 the transistor operates in the cutoff region. So, this region the junctions are both the junctions are reverse biased. So, when the input current IB is constant at the 0 micro ampere the output voltage VCE increases from 0 volt to different voltage levels. The curve is then drawn in between the output current IC and the output voltage VCE at the constant input current which is kept at 0 micro ampere. So, this region is called as active region of the transistor. So, when the voltage VCE is reduced to the small amount 0.2 volt then the collector base junction become forward biased. So, when the both junctions are forward biased the transistor operates in the saturation region. In this region a small increase in the output voltage VCE will rapidly increase the output current IC. Now, we have observed the input characteristics and output characteristics. Let us simulate the common emitter configuration in LTS5 software. So, this is a schematic environment where we are going to draw our circuit. So, from this toolbar you can select the different components. So, go to the component click on that component you will have a option of select this component symbol. So, this is basically a library from where you can select a different component. So, now we need a NPN transistor. So, I will select the NPN transistor and then click on ok. Now, click place your NPN transistor on the schematic by clicking the mouse. In order to deselect the component just press the escape button. You can zoom in and zoom out by scrolling down your mouse. Now, let us add the supply voltage. So, again go to the component option type here voltage. So, we need the voltage at the input. So, I will add the at the input and another the voltage source is needed at the output. So, I will add the another voltage source at the output like this. In order to deselect the component just press the escape. Now, in order to add the resistor go to the option you can see here resistor and click on that resistor option. In order to rotate the component press control R. So, I will add one resistor at the input and I will add one resistor at the output. In order to deselect the component just press escape. Now, in order to connect the component together we will need the wire. So, here is an option of the wire. So, select that option. After selection just go to the terminal where you want to draw the wire. Start from this terminal and end to the another terminal. From this terminal I will connect to the base. From this terminal I will connect to the another terminal and from this resistance terminal I will connect to the positive terminal of the battery. Similarly, the emitter is common. So, it is connected to the negative supply as shown in the figure. So, I will connect it like this. Then I will add the ground. So, here is a ground. So, just add the ground. Now, let us give the value to the resistor. Let me give the value as 680 ohm at the input resistor. If you do not give any symbol here like kilo k m it will automatically by default it will take as a ohm. Click on ok. Then again right click go to the that particular resistor and right click your mouse and add the value of 480 ohm. Now, I will add the supply voltage output as a 5 volt and the input we have to change the input voltage. So, let us I will not give the value right now later on I will give the value. Now, this is a circuit diagram of the common emitter configuration. In order to do the analysis we need a DC characteristic analysis. What we need? We have to make the changes this supply voltage V 1 and V 2 has to be changed from 0 to particular value. So, in order to do that such type of the analysis is called as a DC sweep analysis where the voltage sources are changed to the value from 0 to particular volt. So, go to the option of simulate there is an option of edit simulation command click on that option. So, you can see the different options are available here. So, we do not need the transient analysis now we need the DC sweep analysis. So, as you can see what is written here compute the DC operating point of the circuit while stepping the independent voltage sources and treating the capacitance as open circuit and inductance as a short circuit. It means that what we have we have two voltage sources. So, we have to change this in voltage sources independently. So, what is the first voltage source name? Here the first voltage source has a name of V 1. So, V 1. So, what have we have to change? It has to be changed from linear. So, the start value will be 0 volt and stop value means what 0 to what volt. So, it will be the 1 volt and let us give the increment of 0.01. It means that the voltage source V 1 is changed from 0 to 1 volt in steps of 0.01 volt. So, second voltage source is the V 2 again give the name V 2 the V 2 is changed from 0 to 2 volt in steps of 0.1 volt. So, start value is given as 0 the stop value is given as 2 and the increment is given as 0.1 volt. So, click on ok. As you can see the sweep analysis that we have we are going to do for this circuit is given by this characteristics. So, the we have the DC sweep analysis the voltage source V 1 is changed from 0 to 1 volt in steps of 0.01 and the V 2 is changed from 0 to 2 volt in steps of 0.1 volt. Then in order to simulate this circuit go to the option of run. So, click on that option. So, you can observe the output here and our circuit is here. In order to zoom in zoom out you can scroll your mouse. So, what we need? We need to observe the input characteristics and the output characteristics. So, as you know that the input characteristics is nothing, but the change in the base current I B for the change in the base current V B E. So, if you move your cursor here you can see the voltage symbol and if you move your cursor here it will provide you the base current. If you move your cursor here it will provide you the collector current and if you move your cursor here it will provide you the emitter current. So, I just click on this symbol. So, these are the input characteristics. So, you can observe that from up from 0.7 volt it is in the base current is increasing and the curve is similar to that of the P N junction diode. Now, in order to observe the output characteristics what is what we need? We have to plot the graph of output current I C versus the output collector to emitter voltage V C E. So, here is an option of that output current. So, if you move your cursor at the collector region it will show you the collector current just click on that you can observe the output for the different levels of the input voltage V B E. In this way we have simulated the circuit of bipolar junction transistor in LT SPI software. These are the references of the session. Thank you.