The question reminds me of my questions (meaning of "dynamic", "differential" etc) to the OP's question on negative resistance, using MOSFETs, LTspice etc. If he does not even know basic calculus terms "differentiation", "integration" etc) then we are wasting our time. BTW, the ADC PCA8951 can config with 4 "differential" input channels, but the two "differential" term using in tunnel diode and ADC is completely different, so we need to point out the differences.

As I said from the very beginning, using a lab case study with real things 2BS4 and PCA8951, show them the I-V curve on the scope, also with measurements/readings with DAC and ADC should clarify many confusions and ambiguities etc.

Hi! They are different concepts. In a differential amplifier there is a difference between the voltages applied to two points (inverting and non-inverting input); in the differential resistance there is a difference between two values of the voltage applied across a dynamic resistance.

Why don't you ask a question in Physics about point 2 in the Khan chart? I will answer after that and explain that there is no such point ... It is possible that the situation there is more friendly ...

@Circuitfantasist Yes, The naming or terms in op amp and tunnel diode are confusing. Let me ask you some basic question to warm up. I will first ask questions about op amp, then later about negative resistances.

Question 1: What is the meaning of "Operation" in "Operation Amplifiers"? When I studied my EE diploma, I knew why "pre" amp, "power" amp are called their names, but what is hell is "operation"? Do all your students know the answer?

Ah, I hesitated to ask the "Point 2" in EE SE Q&A, because the so called elites and moderators there are very professional engineers. I have the feeling that look down upon EE diploma holders and gave me unfriendly comments such as (1) "@tlfong01, your question is not useful in our party, ... ", (2) "@tlfong01, you are not "knowledgeable in enough" (or a more harsh word or warning" I forgot) to contribute to answer for question, ... (so I immediately make apologies, ...).

I have never asked any questions in this EE SE Q&A forum, but I guess I made most apologies in this forum, and most down votes, and most closures on my answers (more about my bad experiences here later). So I need to take up courage to go to a new place like physics.se and ask a question, ...

As I said earlier, I need to read Prof Kahn's tutorial and understand thoroughly before I ask a question on "Point Two". I will try to ask that question perhaps tomorrow.

Now I am compiling a reading log of Prof Kahn's lecture: tunneldiode.blogspot.com/2020/11/….

Ah, jogging and supper time. See you late this evening or tomorrow. Cheers.

Hi TL Fong! In the past, op amps have been used to implement mathematical operations in analog computers; hence the name "operating". Today it is synonymous with "quality", "perfect", "almost perfect"... Hmm ... very precise observations on the nature of the "elite" in EE. I also have rich observations and practice in this field ... I can say that I have become almost a psychoanalyst ... and a psychotherapist :)

This morning, I published another paper in Codidact. It is about the philosophy behind current sources. I think it would be interesting for you.

@Circuitfantasist I have summarized another post on "Point 2": tunneldiode.blogspot.com/2020/11/…

I have no idea on how to ask the Point 2 Question. Should I ask something like this: "I have read the article by Poole and Darwazeh, I don't understand why Point 2 is unstable?" But this seems to be a silly question. Or you may like to comment on my second Point 2 post and let me know what goes wrong!

@Circuitfantasist Thank you for your answer. Your mentioning of the word "Mathematical" is most critical to me. All these years, I did not know what "operational" refers to. I never realized that it is mathematical operations (addition, subtraction, and most importantly differentiation and integration), because nowadays everybody used digital mathematical operation, no longer "analog mathematical calculation

Ah too late to go to bed. See you tomorrow or later. Cheers.

Hi, TL Fong! I have fabricated a question and written it in your blog. Of course, I can ask and answer it but the "elite" will be dissatisfied... and we should not irritate it... Also, try to imagine the trajectory of the operating point that it travels when it "jumps" from point 3 to point 1. Regarding current sources, I suggest to you to consider your specific circuit solution of a current source from the perspective of my philosophy...