The timestamps for the different topics covered in the video: 1:11 What is Common Base Configuration 2:55 Input Characteristics of the Common Base Configuration 5:45 Output Characteristics of the Common Base Configuration 6:33 Three Different regions of operation (Active, Saturation, and Cut-off) 10:52 Signal Amplification in CB Configuration
I might've missed it, but introducing the shottkey equation would help. That way, base emitter resistance can be introduced without hindrance, not to mention even that output curve.
all videos are just awesome unbelievable that that area vailiable in utube thank god i got it some how . thanks a lot to u carrry one for other topic also .
The discussion of three connection modes are all mixed up in three videos. Looks like providing the same confusion poorly organised text books are providing. 1. The fact that base current turns on the transistor is common thing, why emphasise that in Common base case configuration? 2. Input and output impedance should be called out in all the configurations. Did you omit that in common emitter configuration, I am not sure? 3. Why common collector discuss alpha beta and gamma. Isn't that a general transistor characteristics? I mean it is good for exam. In other words why a circuit designer should consider these values is more important than jumbled mathematical relationships between them. Beta is the only useful stuff according to me. I am wrong, but your lecutre doesn't point out where I am wrong. 4. Practical help on designing a rudimentary amplifier or switch using a transistor and real available resistors would make these sessions more interesting. My englinnering lectures and labs didn't teach me that, had to learn that myself after playing with some real components and breadboard. 5. Actually the stuff is simple and should be taught in high schools without the scary charts.
Hello Anand, this is a pretty old comment but I loved this comment. The fact that the whole idea of a transistor is so poorly organized in almost all books is notable. Also the idea of what is common is simply the idea of what factor are you measuring. No lecture and book emphasize on this.
Sir I found out one mistake in your video as per my knowledge. In your video you told that the output characteristics curve for common base configuration is linear but I verified from Sedra Smith that the curve is not the liner it has a small positive slope which indicates that the Ic depends upon Vcb in the active mode.
Valuable information thank you so much you made it this topic easy and now i also able to explain this topic to others once again thanking you sir thank you so much
Increasing Vce implies that the depletion region increases, implying that less voltage would be required to forward bias Vbe. How does that make any sense? Shouldn't it have been the other way around
great explanation sir,i have following questions when i watched this video 1).why you don,t use output impedance in your calculations?is that not effect for output voltage and current? 2).same current flow through the circuit from input side to output side . but voltage is increasing without using any voltage source.so the power is increased .how that happened?
the thing is we are also applying the DC voltage to the BJT. AC input signal is the one which we want to amplify. But to do so, we need to bias the BJT (we need to apply the proper DC voltage to the BJT). This external DC biasing helps in the amplification. There is a conservation of energy. For more info, I would recommend you to watch the video on BJT- Large signal model. Here is the link: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ME41uPsDxFo.html
Typically the output impedance in this configuration is very high. It will come in parallel with RL. And if we take the parallel combination of those two resistors then it is close to RL. That’s why here it is not considered. For exact calculations you can watch the video on common base amplifier. Here is the link : ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MckBbhfxdkk.htmlsi=dYJmsP0UI30uVH_q
great video. However I have aquestion. We can see that in output, collector current is given by alpha times emitter current. I want to know why does the output voltage (Vc) not have an effect on that. I know the mathematical relation but whats the actual reason?
when we say, the common base, the base is common for the AC signal. That means the AC input signal is applied between the emitter and the base, while the output is measured between the collector and the base. For the DC biasing perspective, the base terminal may not be at the ground potential. But to use the BJT as an amplifier, the base-emitter junction has to be forward biased and the collector-base junction has to be reverse biased. (To ensure the operation in the active region) Actually w.r.t to ground there will be some finite DC voltage at the base. Here to simplify the analysis it shown such way. I hope it will clear your doubt. If you still have any doubt then do let me know here.
Hello Sir, I have a question for the constant Ic when Vcb increase. As what you said in common emitter transistor, as Vcb incrases, the depletion region will increase so that the effective width between base and emitter decreases. Thus, more electrons will flux into collector region. That explanation could also be applied here. Then Ic should not be constant. Instead it should also increase. But why does the current keep constant here? Thank you very much for your video!
During the whole video you have explained using an NPN transistor. Why couldn't you use NPN while showing the amplification example at last ? Why did you have to switch to PNP ? Can you please demonstrate the amplification using an NPN transistor too ?
Minority charge carriers are responsible for current if the diode is connected in reverse bias is that mean minority charge carriers in both p side and n side??plz answer...
sir is it supposed that when we increased VCB then we make the junction between base and collector more reversed then the collector current reduced not to be constant ?
I have one doubt in my mind ..if collector Base junction is in reverse bias then why electrons from emitter move from reverse bias depletion region ? Why dont electron pushed back to emitter by repeltion of negative ions of P-region of base?Is there breakdown occur at reverse bias depletion region? Please answar and clear my doubt
Here, emitter base junction is forward baised. That means electrons will be move towards the base region (Due to the repulsive force by the negative terminal of the voltage Vee ) and holes will get atteracted towards the negatvie terminal of the emitter voltage (Vee). At the same time collector base junction is reverse biased. So, once the electrons enters the base region, they will behave like a minority charge carriers. And they will get pushed by the electric field of the reverse bias voltage at the collecor base terminals. So, as a minority carrier they will reach into the collector region . And then by the force of the positive terminal of the Vcc, they will get attracted towards it. I hope, I am able to clear your doubt. If you still have any doubt, please let me know here.
Thank you very much..i understood this concept its due to electric field..Can u clear one more doubt ..how BJT amplified signal means increase output power if we know that power is fixed and we can't generate it ..i understand mathematical reason of voltage and current amplification but what is physical reason?..Can we call BJT mixing input power with battery power so output power become high?
@ 5:01 You mentioned the Input impedance [is the slope of the curve; i.e TanX. But here, TanX=Per/Base= Ie/Vbe; which doesn't seem to be the Impedance from the curve. Please correct it.
Impedance is resistance here (R = V/I). For input characteristics, changes in I is very big compared to the changes in V. That's why, impudance is low.
I want to thank you again. How did the high output resistance help this circuit? As the output voltage was dependent on load resistant. I figured from the output characteristics, that the high o/p resistance is helping for a current mirror as the current does not change much but does it help for voltage amplification purpose?
I have a dought sir, what is the difference between Vbb, Vee and Veb when the base is common. And the volatege is always apllied between base and emitter then why three different notations are used
At 4:55 , u said input impedance as slope of the graph... And we all know slope is always defined as change in y divided by change in x....but then u define Ri= change in Vbe / change in Ie.. Can you explain?
Ri is the inverse of the slope. The slope gives you the conductance. That's why it is change in the Vbe to the change in Ie. I hope it will clear your doubt.
I have a doubt, why in output characteristics we consider Current of Collector, since current is going inside the transistor so shudnt it be input characteristics? Or do we consider the direction of electron?
Its really a good video ,but I have one doubt , voltage gain is actually based on load resistance, which we can change according to our convenience than why its rage is fixed?
In common base amplifier, along with load resistor, the gain also depends on the collector resistor and the transconductance. That's why just increasing the load resistance alone, you will not see much increase in the gain after some point. For more information, about the gain of the common base amplifier, you may refer this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MckBbhfxdkk.htmlsi=1KOQ9EApVd8GTiZy
I have posted a few Quiz related to BJT on the second channel. Here is the link: ru-vid.com/show-UCGA2TO8ylVqFHpucwn_6Jlw And soon many more will be posted.
I have a doubt, you have written in properties of CB that it has low power gain, but if current gain is 1 then power gain is same as the voltage gain and so it is high. Right?
Because it is PNP transistor. So, its direction will be opposite to NPN transistor. The transistor shown earlier was NPN transistor. I hope, it will clear your doubt.
How is the voltage from the Base to Emitter considered to forward biased for both the PNP and NPN when they are on? Is this not a mistake? If you're talking about Vbe in both cases then they both can not be considered forward biased. The only way it makes sense is if in regards to the PNP you are saying Veb is forward biased. But why do it like that?
If collector base junction width is increased then base current will decrease and collector current increases but i dont understand why emitter current increased if the collector base juction width is increased?
The output will be Io x ( Ro || RL). But since, RL is much smaller than Ro, (Ro is around 100k and ,RL in this case is 1 k) their equivalent resistance will be approximately equal to RL. That is why RL was used. I hope, it will clear your doubt.
Yes, exactly. I was wondering this comment. He used PNP transistor here, but in both NPN and PNP, the i/p will be along VBE side and o/p will be on VCB side. So there's no problem with the equations though.
y in active region, Vcb didn't affect Ie, but at input characteristic there Vcb increase, Ie also will increase?!!!!!can someone explain to me, urgent!!!
You will get the output between the collector and the base terminal. But usually, the output is connected to the load. So, if you connect the load resistor RL across the two-terminal then you will get the same output across the load resistor. I hope it will clear your doubt.
At 6.17 you explain input and output characteristics...while explaining input characteristics u kept output voltage constant while output characteristics u put input current constant why such so?
If you change any input/ output parameter, it will have an effect on other parameters as well. So, the while finding output characteristics we just want to know how Ic changes with VCB. If we change input parameter ( Ie) then it will also affect the collector current. So, it is kept constant. In short, while finding characteristics, we don't want more than two variables. That's why input parameter is kept constant. I hope, it will clear your doubt.
I want to know why is current not voltage is taken constant while plotting output characteristics or vice-versa? I got your point but why current nd voltage are taken why not same in both characteristic?
It depends how the amplifier is configured. Some amplifier amplifies current, some voltage, while some amplifiers are power amplifier and amplifies both current and voltage.
@@aamir99204 Yes, just to explain the signal amplification in CB configuration, the PNP transistor was shown. (since the direction of input and output currents are more relatable in PNP CB configuration)
