173N. Thermal white noise physics, properties, and spectrum, KT/C noise, total available noise power

[@sohamlakhote9822]

Kids wait for GOT episode, real men wait for Hajimiri Sir's lecture :-) I get shocked atleast 2-3 times during the lecture thinking about why book's author didn't explain the concept in such a intuitive way. Thanks a lot Dr!! Will you please make lectures on phase noise and PLL so that it would be easy for us to gain more understanding from your research papers ? :-)

[@bios546]

Gained a real, deep insight on stuff I never, ever would've if not've watched these lectures... Thanks so much sir... Thanks so much.

[@ahmedmuhammed6905]

One of greatest lecture that i ve seen

[@-Oleg1]

Thank you very much. Very fundamental explanation

[@rfahimur26]

Excellent lecture. One thing just popped in my mind: can we make a temperature sensor based on the fact that rms voltage across capacitor is KT/C? I think that should be more accurate than the PTAT-based temperature sensors. But we have to average long enough to get rms voltage.

[@snnwstt]

Even I can, or at least, have the impression that, I understand. Until you isolate the transmission line (23:30). Ok to admit that at a "sustainned" case, the energy will "vibrate" at a natural frequency of the system, and that we will have modes matching an (inverse) integer times of the Length, but ... Nothing forces us to say that it was ALSO the way power was transmitted before the cut-off. A little bit like a vibrating string of a violin, it may, for a time, produces a dissonent sound ("unpleasing to the ears", would have say Pythagoras). Or, if you prefer, what happen if the Length increases (due to temperature or otherwise), the modes would have to ... transit... to other modes. Is that transition, modifications of the modes , of no (or negligeable) influence on the amount of power present in the transmission line?

[@ZiqIman]

Shaik shahrul was here

[@KipIngram]

41:37 - You have to add them in whatever way yields the right noise source for the equivalent parallel resistor. Your current sources aren't necessarily going in the same direction at any given time, so you can't just add them. Sometimes they CANCEL one another. But anyway, I'd just compute the parallel resistance and use that in the usual formula, rather than trying to add the sources.

[@snnwstt]

4:07 "they are put in parallel"... they are more in sequence, in series, isn't it? If they were in parallel, they will be at the same voltage potential , isn't ? (Even it that detail is somehow irrelevant here)

[@KipIngram]

26:26 - Ok, question. While the t-line is connected between the two resistors, neither resistor realizes that a t-line is there. You look out from a resistor's terminals, and you just see R. A resistance. The resistor has no idea whether that's a t-line with impedance R connected to a resistance of R on the other end, or just a direct connection to another resistor. So why does it deliver energy at particular frequencies? I get it that once you short the ends of the t-line only certain modes survive, but prior to shorting the ends it seems like any frequency at all could enter the line. The length is irrelevant, because it's matched at the far end and there's no reflection. You stuff energy into one end and it never comes back. So how do we reconcile all of this? The best I can imagine is that all frequencies are first in the t-line, but at the instant we short it there occurs a transient period where the non-modal frequencies die away, and the energy in those frequencies shifts into modal frequencies.

[@dssorkin860]

This is my thinking. If you assume spectrum profiles both resistor the same as it should be you can limit delta f to single frequency.No need to shorten ends of transmission line to the ground. Both end will be at the same potential and support standing waves.The same for every other mods.

[@LeftieLouie]

YES! FANTASTIC!

[@divyakaur9516]

if noise power is independent of resistor, then does that mean a 1k and a 1G have same power?

[@snnwstt]

Or that the resistance of the whole universe has the same "noise thermal power" than a single one ohm resistor (If that interpretation makes sense) ?

[@agstechnicalsupport]

Well explained Ali, thank you ! We are looking for an experienced electronics engineer specialized in noise troubleshooting. If you or someone you know can help us as a consultant, please let us know. We are willing to hire an electronics noise expert on a contract basis for a challenging noise issue.