120N. (Pt.2) Amplifier Fundamentals, MOS, BJT, and ATD (arbitrary 3-terminal device), maximum gain
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- Опубликовано: 8 ноя 2024
- Analog Circuit Design (New 2019)
Professor Ali Hajimiri
California Institute of Technology (Caltech)
chic.caltech.ed...
© Copyright, Ali Hajimiri
Prof Hajimiri teaches with such details and flawlessness, makes it look so easy! and best videos ever.
The passion you have for both teaching and EE shines through in these videos. Thank you for sharing them beyond Caltech!
Thank you for your kindness. I am glad you find them useful.
Professor, the last time I studied these concepts was almost 12 years ago, but now I have a lot more insight by watching your lecture. Thank you for sharing your knowledge.
Professor i would like to make an obesrvation at the stage where you express the internal gain of the device as gm*ro and state that its maximum at subhtreshold region versus the drain current. Supposing that a mosfet in weak-inversion has a BJT alike small signal model and the gain is maximun and also low power why we do not use this in this region for audio amplifier? I am maybe wrong and i am sorry for the question, but i agree that the ft(cut off freq_) of the devise which is roughly equal to gm/Cπ will be very small at subthreshold as gm is equal roughly to 10^-8, so one point is that it will be an amplifier with extremely low bandwidth. But an audio amp must amplifiy signals between 20-20K Hz so it does not require a large cut off frequency mosfer so why not use them for this operation biased in weak-regime? Thank you in advanse
Hello Sir,
When we talk about Rout of a MOSFET, I just want to understand what it physically means? Does it mean the resistance of the "pinched off channel" or the entire channel? Similarly for a BJT, the Rpi? Is it the resistance that the charge carriers face while going from Base to emitter?
Thank You
The effective resistance of the entire network seen inward at the output side, which'll be resultant of a cumulative effect of various things, even stuff that couples the input to output at higher freq.... or so I assume.
Hi Sir Hajimiri,
In the resistor portion of the square law equation (lambda * VDS), there are books that include the overdrive voltage or VDSSAT (i.e. lambda (VDS - VDSSAT) ? Why did you remove the VDS saturation voltage ? Doesn't the VDSSAT term in the equation consider the boundary between saturation and triode region i.e. locus of (VDSSAT, IDSSAT) points ?
Thank you.
So hi sir,, as we even after taking the subthreshold current into consideration still gain is higher at that proximity only so can we really keep our transistors to operate at this region for any high gain device and fabricate them into the silicon?? Pls reply if u see this.
Thanks