eight hours before exam and im cramming through these Razavi vids Hopefully this will help a bit Thanks for Professor Razavi and the uploader of these vids!
I find it very satisfying how these circuits are frequently analysed with Ohm's Law, KCL *_and_* KVL. That's like one big refresher of the most important analysis techniques from Circuit Theory.
Hello, just wanted to point out, that I believe you ended up mixing R1 & R2 from your 1st example. If we see that R1 + R2 = 15k Ohms, then we see that: R2/(R1+R2) = 0.9/Vcc R2/(15k) = 0.6 therefore, R2 = 9k Ohms and R1 = 6k Ohms PS: Thank you very much for these extremely helpful lectures! Very good work!
Vx is a voltage on base w.r.t ground and Vc is a voltage on collector w.r.t ground.... now to make base collector jxn RB VC >= Vx. And that is what razavi sir has written..... I think your doubt will be cleared by the following equation. (Vc - Ve) >= (Vx - Ve)
I don't understand this : At 28:10 professor says that you need V_c > V_x which is V_x = 0.9Volt. BUT. For reverse biasing between the Collector and the Base, you want V_ce > V_be, so V_c has to be bigger than 0.8V which is chosen for V_be. I guess I'm wrong, but I don't know why. Anyone care to explain ?
Vcc - IcRc is the voltage across Rc. That is the collector voltage Vc. Now Vx is essentially the Base-emitter voltage. Therefore, the Vc voltage must be equal or greater than Vx so as the transistor stays is the forward active region. Now here the Vcc is 1.5V, Rc came out to be 600ohm and Ic was 1mA. On putting these values in the equation Vc = Vcc- IcRc, we get a collector voltage of 0.9V which is same as the Vx, Please make note these values chosen by professor are just for understanding and not as accurate as they should be, because now the transistor in kinda on the verge of soft-saturation, as Vc has came out exactly equal to Vx.. Yet the model is good enough for understanding the underlying concept. hope this helps:)
@@ajayrajan8882 Hi. I'm sorry but i think your explanation is little bit wrong. Vx is not a Base-Emitter voltage, but rather the voltage between base and ground. To make transistor in forward active region, (suppose it's npn transistor), we need a reverse bias between collector and base. Therefore, Vc>Vx. The original question was why V_ce>V_be. At lecture 17, professor mentioned that (again, suppose npn transistor) 1. collector and base junction is zero or reverse biased 2. base and emitter junction is forward biased. when these two conditions are met, we call it Active Forward Bias. Therefore to precisely satisfy Active Forward Bias, we need V_c > V_x.
eight hours before exam and im cramming through these Razavi vids
Hopefully this will help a bit
Thanks for Professor Razavi and the uploader of these vids!
I find it very satisfying how these circuits are frequently analysed with Ohm's Law, KCL *_and_* KVL.
That's like one big refresher of the most important analysis techniques from Circuit Theory.
22:30 Current (I) = Power(P)/Voltage(V)
They still give the same result as in this example P=V
It was just a slip of the tounge
@@mr.ANIMAT0N not the same result, current would be of Kilo Amps magnitude in this case, Also P and V are not of same order
22:30
Icc = P / Vcc
nothing changes though
@@serden8804 but still
Hello, just wanted to point out, that I believe you ended up mixing R1 & R2 from your 1st example.
If we see that R1 + R2 = 15k Ohms, then we see that:
R2/(R1+R2) = 0.9/Vcc
R2/(15k) = 0.6 therefore,
R2 = 9k Ohms and R1 = 6k Ohms
PS: Thank you very much for these extremely helpful lectures! Very good work!
Hope you are doing good buddy.
@@Upgradezz Hope you both are doing good ?!
Thank you from the bottom of my heart ❤
Why wasn't vcc change modeled into the small signal model from the output side?
20:37 shouldn't it be Vx- Ve in RHS? As base emitter voltage isn't Vx but the difference Vx-Ve
Vx is a voltage on base w.r.t ground and Vc is a voltage on collector w.r.t ground.... now to make base collector jxn RB VC >= Vx.
And that is what razavi sir has written.....
I think your doubt will be cleared by the following equation.
(Vc - Ve) >= (Vx - Ve)
HEY WHAT HAPPENED TO INTRO MUSIC......EARLIER IT HAD "VIVALDI FOUR SEASONS".....IT WAS LIKE THEME SONG OF "GOT" I NEVER SKIPPED IT
It's in the outro.
"Idea evolves" by Behzad Razavi
I don't understand this : At 28:10 professor says that you need V_c > V_x which is V_x = 0.9Volt. BUT. For reverse biasing between the Collector and the Base, you want V_ce > V_be, so V_c has to be bigger than 0.8V which is chosen for V_be. I guess I'm wrong, but I don't know why. Anyone care to explain ?
Vcc - IcRc is the voltage across Rc.
That is the collector voltage Vc.
Now Vx is essentially the Base-emitter voltage. Therefore, the Vc voltage must be equal or greater than Vx so as the transistor stays is the forward active region.
Now here the Vcc is 1.5V, Rc came out to be 600ohm and Ic was 1mA. On putting these values in the equation Vc = Vcc- IcRc, we get a collector voltage of 0.9V which is same as the Vx,
Please make note these values chosen by professor are just for understanding and not as accurate as they should be, because now the transistor in kinda on the verge of soft-saturation, as Vc has came out exactly equal to Vx.. Yet the model is good enough for understanding the underlying concept.
hope this helps:)
@@ajayrajan8882 Hi. I'm sorry but i think your explanation is little bit wrong. Vx is not a Base-Emitter voltage, but rather the voltage between base and ground. To make transistor in forward active region, (suppose it's npn transistor), we need a reverse bias between collector and base. Therefore, Vc>Vx.
The original question was why V_ce>V_be. At lecture 17, professor mentioned that (again, suppose npn transistor)
1. collector and base junction is zero or reverse biased
2. base and emitter junction is forward biased.
when these two conditions are met, we call it Active Forward Bias.
Therefore to precisely satisfy Active Forward Bias, we need V_c > V_x.
FYI, the term should be corrected to "Forward Active Bias".
the circuit won't bite:(
can someone write equation of Rout/Rin please.
1:01:11 Is there anyone here to explain why Rf equals betaRc divided by 10?
it's just an assumption since betaRc >> Rf
32:12 I think he got the gain wrong. It is nearly 6 but he got 4.76.
1/gm ~26ohm so it cannot be neglected.
37:07