Cool

He's God

@@mrpossible5696 No He is God Gifted. I think as a Muslim he personally will not like being called god.

@@mutiurrehman4418 I agree

​@@mutiurrehman4418you don't actually know though if he is muslim, he is just from iran, ask him first

Since we proved at around 20:00 that the source voltage (Vp) does not change for small signal inputs, professor has deduced that the points of symmetry in a symmetrical circuit are points which are not affected by small signals and are thus AC grounded. Alternatively, if you want to consider the effect of the other MOS device while finding the gain, what you could do is find Vx and Vy for Vin1 considering Vin2 to be grounded and vice versa. Hence you could find (Vx-Vy) wrt Vin1 and wrt to Vin2 from which you could find out Av. It is just a little bit more complicated process.

rewatch at 18:10

VCM in lecture 12 is DC common mode voltage. whereas change in vin in this lecture he is talking in small signal change.

The *biasing current* in NMOS devices flows from the drain to source; whereas in PMOS devices it's the opposite. So, when 2 NMOS( or 2 PMOS) devices are interconnected as a differential pair, the tail current source (= _Iss_ ) should be placed to ensure that the biasing current flows in the appropriate direction through the respective devices.

that current source in real design is a biased transistor who plays role of current source, you can not do the reverse because NMOS is steering-current device and PMOS is a pushing-current device

yes，he missed Iss in the root.but it begins with "(Iss/2) + "also xd

yes you're correct just the plus sign between Iss/2 and the square root ID1 = (Iss/2) + sqrt(Un * Cox * W/L * Iss) * Delta_V

yes

There is bro like Ali Hajimiri

In this equation Vgs is changing as well. You are keeping Id constant and changing W, so Vgs has to change, so you cannot use this equation. I am commenting after one year, you must have figured it already :)

I am hoping my son will be able to watch the circuit theory I & II and the rest of the series in Year 2050

@@ayushmeena5708 I believe it's out there but not leaked to youtube yet

@@mnada72 Ohh can you please share it, God will surely bless you for that

That's correct, but in this case, with Vin1 & Vin2 changing differentialy, Vp remains constant (it's a virtual GND); observe that ideal current sources don't behave in this way, only current remains constant for any load connected; then, in small-signal analysis this node is ac GND. I suggest to you review lecture 10 of this course, for a better explanation.

Long Kong is a student of Professor Razavi, he himself is a PhD from UCLA, working in Apple as an senior RF IC design Engineer and has also published various papers along with proff Razavi.