Do you think an LED is a resistor?

[MK14]

Just for anyone who is interested, the OP seemed to be talking about the topic of this thread, around a couple of years ago.

You can call it generalized Ohm's law.

There is a vicious rumor that diodes are not resistors, but they are resistors. They are nonlinear resistors (if we neglect the dynamic parasitics, of course and assume the exponential curve in the VI plane is what characterize them).
If you need to invoke the principle of authority to defend this assertion, you can always quote Chua, Desoer, Kuh, "Linear and Nonlinear Circuits". This is what I call "THE bible of circuit theory". It's not some high school or vocational school textbook for courses limited to the easiest circuits.

[fourfathom]

Is a dog a cat?

[Gyro]

Well, up to a few posts ago, "nonlinear resistor" was an oxymoron, so it's progress.

Try this. Go here: https://automobiles.honda.com/ (or any other car manufacturer) and try to find a Formula1 race car for sale.
If you can't find it then Formula 1 race cars are not cars.

Helen is a woman, even if you don't find it in the list of women whose name starts with K, like Kate.

After 8 pages, why are you folks continuing to feed this guy? 

Just for entertainment value?

[fourfathom]

Just for entertainment value?

Yes.

[MK14]

To the OP.
Are you sure you are talking about a 'normal' diode, and not a 'special' type of (apparently chaotic) diode?

You seem to have given too little information for me to be sure.

But, are you thinking of Chua's diode?

https://en.wikipedia.org/wiki/Chua%27s_diode

https://en.wikipedia.org/wiki/Leon_O._Chua

https://en.wikipedia.org/wiki/Chua%27s_circuit

[Gyro]

Just for entertainment value?

Yes.

Just checking, knock yourselves out then.

[Zero999]

I suppose a noisy reverse biased zener or BJT junction is a special type of resistor with a random element to it.

[Someone]

non linear system has linear approximation around a small operating point....

STOP THE PRESSES!

... oh wait, that's the underlying principle of how spice AC analysis works.

Small signal analysis has nothing to do with what we are discussing here.
The resistance I talk about is the static resistance, not the dynamic or incremental resistance of small signal analysis.

Try again.

That was your long winded and dithering proof:

So, we are now seeing the diode as a voltage dependent resistor. Let's see... what is the resistance 400mV? Let's zoom in:

[MASSIVE IMAGE]

I'd say it's about 23.2 kohm.
Let's see what is the resistance at, I don't know, 660 mV (about 5mA of diode current). We can compute it by hand of course, but on the graph we see it is 132 ohm.

[MASSIVE IMAGE]

Now, let's see if we can make something with these values...
[snipping conversational fluff]
Ok, exact same results, if we neglect a bit of rounding error in reading and setting the values.
Now, take your black boxes out of the fridge. Put the diodes D1 and D2, and the resistors R1 and R2 inside a black box each. Shuffle them around. And tell me: without looking inside the black boxes and without resorting to second order effects (like temperature dependence, or changing the other circuital parameters to change the operating points) can you tell me which are the diodes and which are the resistors, by simply measuring voltages, currents and powers?

So to try and claim you're not relying on the well known small signal AC parameters is plainly incorrect.

If you dont like relying on small signal characteristics, perhaps "try again" with your explanation/justification.

Again, small signal analysis has nothing to do with anything I have written in that post.
Nothing.
I zoomed in on the V-R characteristic to find an accurate value of the static resistance. Not the dynamic, or incremental, or small signal resistance.
Then I used the static resistance at a chosen voltage or current to choose the limiting resistor that would have set the chosen operating point.
Then I showed that using a resistor with the correct static resistance value would give the same variables in the circuit..
If you want to waste a bit of time you can create in LTspice a voltage controlled resistor that has the same R=R(V) dependence of a 1N4148. You will then see that it will behave (secondary effects apart) as a diode, confirming that it's the variable resistance. that gives a diode its behavior.

Go ahead and try.

Oh new words and definitions to play with. How about we take the IEEE dictionary as the authoritative reference:

static resistance (semiconductor rectifier device) (forward or reverse) The quotient of the voltage by the current at a stated point on the static characteristic curve.

small-signal resistance The resistive part of the quotient of incremental voltage by incremental current under stated operating conditions.

small-signal A signal which when doubled in magnitude does not produce a change in the parameter being measured that is greater than the required accuracy of the measurement.

As I said in my opening statement, you're just playing with small signal analysis a well known and entirely un-novel method. There is nothing interesting here as most anything can be described as a small signal resistor (with bounds on some other dimension). So you're still wrong and trying to twist definitions to your liking while ignoring the consensus and the established science.

[Sredni]

To the OP.
Are you sure you are talking about a 'normal' diode, and not a 'special' type of (apparently chaotic) diode?

I am talking about ordinary signal diode, power diodes, zener diodes, tunnel diodes.
Have any of you even opened the Science Direct link I gave before?

From here (a page that is apparently invisible to many browsers)
https://www.sciencedirect.com/topics/engineering/nonlinear-resistor

Nonlinear Resistor
Nonlinear resistors have a common characteristic that their constitutive relationships are described by nonlinear algebraic equations.
From: The Electrical Engineering Handbook, 2005
 

From: A.C. Fischer-Cripps, in Newnes Interfacing Companion, 2002
3.3.7 Log amplifier
A non-linear resistor is connected into the feedback circuit. In practice, this can be a diode, but a transistor connected as a diode is used since the forward biased transfer function is more accurately exponential. The exponential nature of the forward biased diode leads to a logarithmic decrease in gain of the circuit as the input signal is increased.



From: A Gavrilović OBE, in Electrical Engineer's Reference Book (Sixteenth Edition), 2003
32.6.3 Surge arresters
The zinc-oxide non-linear resistor material used in modern surge arresters exhibits a very high impedance at normal applied voltage whilst at a voltage only some 50% higher a very low impedance is provided. The extremely non-linear relationship between voltage and current shown in Figure 32.20, has rendered obsolete the spark gaps which were a feature of previous arresters based on silicon carbide.
 

From: I.D. Mayergoyz, W. Lawson, in Basic Electric Circuit Theory, 1997
EXAMPLE 5.5 A Voltage Regulator Circuit
Consider the circuit shown in Figure 5.31, where a load resistor RL is connected in parallel with a nonlinear resistor characterized by the v1(i) curve shown in Figure 5.32. This curve exhibits “voltage saturation.” In other words, it has an almost horizontal (flat) portion which starts from small current values. We would like to find all currents and voltages in this circuit.



[note1: you know what is that curious component represented by a resistor symbol with two lines? It's a zener diode. A special kind of nonlinear resistor]

[note2: the above book as a section titled "Non-linear resistive circuits" where nonlinear resistors are introduced and diode and zener diode are used as examples of nonlinear resistors]

From YIN Jijun, ... LI Peng, in Unified Power Flow Controller Technology and Application, 2017
6.1.1.2.4 Metal oxide surge arresters
Gapless metal oxide surge arresters are used in a UPFC. In the simulation model, they can be replaced by nonlinear resistors. The nonlinear volt-ampere characteristics of valves are shown in Fig. 6.5.



From: Nasser Tleis BSc (Hons), MSc, PhD, CEng, FIET, M-CIGRE, in Power Systems Modelling and Fault Analysis (Second Edition), 2019
10.4.8 Passive damped resonant limiter
Fig. 10.10 illustrates one phase of a three-phase damped resonant limiter circuit that uses only passive components.



The limiter consists of an isolation transformer whose primary winding is connected in series with the ac system and a capacitor is connected across its secondary winding. A nonlinear resistor, for example, a varistor, or a fast-closing triggered switch, is connected in parallel with the capacitor, and a damped tuned filter is connected in parallel with the capacitor/varistor. Under normal unfaulted system condition, the secondary circuit appears as a capacitor at 50 Hz that, when transferred to the primary of the transformer, is equal to and hence cancels out the transformer’s leakage reactance. Therefore, at 50 Hz, the limiter appears as a short circuit except for the resistance of the transformer.
 

So, I hope there will be no more discussion about the usage of the term "nonlinear resistor". It is not a novel invention by Chua alone. It is a well known and estabilished term that encompasses, among others, diodes, transistors connected as diodes, zener diodes, varistors, incandescent lamps, neon lamps, etc. etc. etc.

I think we are left with the doubt if nonlinear resistors are... resistors. No kidding.

[Sredni]

Oh new words and definitions to play with. How about we take the IEEE dictionary as the authoritative reference:

static resistance (semiconductor rectifier device) (forward or reverse) The quotient of the voltage by the current at a stated point on the static characteristic curve.

Yes, this is the only one I have used. Did you not realize it?

small-signal resistance The resistive part of the quotient of incremental voltage by incremental current under stated operating conditions.

small-signal A signal which when doubled in magnitude does not produce a change in the parameter being measured that is greater than the required accuracy of the measurement.

As I said in my opening statement, you're just playing with small signal analysis a well known and entirely un-novel method. There is nothing interesting here as most anything can be described as a small signal resistor (with bounds on some other dimension). So you're still wrong and trying to twist definitions to your liking while ignoring the consensus and the established science.

No, I have not used small signal analysis. Where did you study small signal analysis? You are mistaken. Please seek tutoring from someone you trust to straighten this out.

[Kim Christensen]

From: A.C. Fischer-Cripps, in Newnes Interfacing Companion, 2002
3.3.7 Log amplifier
A non-linear resistor is connected into the feedback circuit. In practice, this can be a diode, but a transistor connected as a diode is used since the forward biased transfer function is more accurately exponential. The exponential nature of the forward biased diode leads to a logarithmic decrease in gain of the circuit as the input signal is increased.

Notice that they didn't write this:

A non-linear resistor is connected into the feedback circuit. In practice, this can be a resistor, but a resistor connected as a resistor is used since the forward biased transfer function is more accurately exponential. The exponential nature of the forward biased resistor leads to a logarithmic decrease in gain of the circuit as the input signal is increased.

 

[Someone]

Oh new words and definitions to play with. How about we take the IEEE dictionary as the authoritative reference:

static resistance (semiconductor rectifier device) (forward or reverse) The quotient of the voltage by the current at a stated point on the static characteristic curve.

Yes, this is the only one I have used. Did you not realize it?

small-signal resistance The resistive part of the quotient of incremental voltage by incremental current under stated operating conditions.

small-signal A signal which when doubled in magnitude does not produce a change in the parameter being measured that is greater than the required accuracy of the measurement.

As I said in my opening statement, you're just playing with small signal analysis a well known and entirely un-novel method. There is nothing interesting here as most anything can be described as a small signal resistor (with bounds on some other dimension). So you're still wrong and trying to twist definitions to your liking while ignoring the consensus and the established science.

No, I have not used small signal analysis. Where did you study small signal analysis? You are mistaken. Please seek tutoring from someone you trust to straighten this out.

You live in a continuous world with no quantisation or noise? Perhaps in your world there is some difference between those. For those of us in the world I inhabit they are the same thing, an exact derivative of infinitely narrow width does not exist physically or in spice (which you chose to introduce). Both static resistance and small-signal analysis are a delta V on delta I.

[Sredni]

Notice that they didn't write this:

A non-linear resistor is connected into the feedback circuit. In practice, this can be a resistor, but a resistor connected as a resistor is used since the forward biased transfer function is more accurately exponential. The exponential nature of the forward biased resistor leads to a logarithmic decrease in gain of the circuit as the input signal is increased.

 

I don't know. Maybe they are used to specific names, like calling their wifes Helen and Kate, and not just "woman".
They are in good company, tho. For example Bharathwaj Muthuswamy and Santo Banerjee, in their "Introduction to Nonlinear Circuits and Networks", Springer (2019) say:

In order to be able to use nonlinear resistors effectively in a practical design, it is necessary to understand some basic properties.We will illustrate these properties by considering a prototypical example of a nonlinear resistor, the pn-junction diode (henceforth referred to as diode). Although we model diodes as nonlinear resistors, they are so important in circuit theory that they have their own symbol[...]

But, hey, what could they possibly know about circuits and nonlinear elements? They only wrote a book about them.
How many books have you written for Springer?

[bdunham7]

In order to be able to use nonlinear resistors effectively in a practical design, it is necessary to understand some basic properties.We will illustrate these properties by considering a prototypical example of a nonlinear resistor, the pn-junction diode (henceforth referred to as diode). Although we model diodes as nonlinear resistors, they are so important in circuit theory that they have their own symbol[...]

Um, yeah....I think they're right about that....hey, I think we have these things called linear resistors, also known as 'ohmic', and don't they have their own symbol and all that?  We call them, um, er, it's at the tip of my tongue....

[Sredni]

Ok, it really is basic comprehension of inclusion.
Watch this first
https://youtu.be/5_oCRtEN2pI

Then consider the set of the following elements:

Diodes (has its own name and symbol)
Zener diodes (has its own name and symbol)
Tunnel diodes (has its own name and symbol)
Metal Oxide Varistor (has its own name and symbol)
Neon NE2 lamp (has its own name and symbol)
Incandescent lamp (has its own name and symbol)

This is a set of...
of...



...nonlinear resistors!
Yeahhhhh!

Now take this big huge set of nonlinear resistors, and put it near the set of linear resistors (they also have their own symbol).
What have you got now? What is the set formed by the set of linear and nonlinear resistors?
It's a set of...
...


Resistors!
Yeahhhh!

Since linear resistors are so to speak the default, we give them the short name of resistors (after all they have been introduced with this name in high school). I hope this won't confuse you.
But apparently it does. Big time.

We call ordinary cars just "cars" even if the set of cars includes formula1 race cars. So, in the same vein the set of cars contains the cars you can drive on public road  (which are called just "cars") and the F1 racing cars, which you can't drive on public roads. The F1 cars have their own name, their own circuit, their own regulations but are still part of the greater set "cars", but are disjoint from the set of public road homologated cars (or "cars" in short).

[Kim Christensen]

Ok, it really is basic comprehension of inclusion.

Yea, and you fail it badly! 

And now, I'm going to "unsubscribe" to this thread, and leave you to your "own devices".

[MK14]

This is a set of...
of...



...nonlinear resistors!
Yeahhhhh!

Now take this big huge set of nonlinear resistors, and put it near the set of linear resistors (they also have their own symbol).
What have you got now? What is the set formed by the set of linear and nonlinear resistors?
It's a set of...
...


Resistors!
Yeahhhh!

I hoped (it was somewhat intentional on my part), that my recent post(s) in this thread, would elisit, more information from you (the OP), as to what you thought was going on, and it seems to have worked, as you seemed to have done that.

In summary and as a sort of analogy, this is how I seem to understand, the point(s)/concept(s) you seem to be trying to portray.

(Hypothetically speaking, i.e. I have NOT just done this).
I create an interesting and long new thread on here, describing my new $50,000 electric car, which happens to have (very approximately), a 100 volt battery set up, along with a 100kW motor (engine if you like).  I have then described the technical details, of all its (interesting to some) systems and functionalities.

You have now jumped into my (hypothetical) thread, and said ...
"no no NO NOOOOOOO!!!!, what nonsense MK14 is talking ......"

This is all really a 1 milliohm resistor (non-linear resistor), with a supplied link to a set theory YouTube video, for very young people.

So, although there is a little bit of technical merit (correctness), and the $50,000 new car, is a bit like (sort of, at a stretch of the imagination), a 1 milliohm resistor (non-linear).

The vast bulk of the time, and to almost everyone, it is NOT a useful, interesting or good way of expressing, what it is.

E.g. Which thread title would people be more likely to click on?

"I just bought my great new, $50,000 super fast electric car, technical details of all its electronic systems included, with advanced AI self-driving to level 3"

Or

"Today I bought a 1 milliohm, (non-linear) resistor"?
The start of the thread then says...
100V 100kW (max)


I hope my analogy is accurate?

[TopQuark]

The terms resistor or diode are just words we humans coined to describe certain electrical devices with a specific electrical property, to help us engineers abstractly express how our circuit design works and it's expected behavior.

There's no reason why you couldn't call every 2-leaded device as a resistor:

- A diode is a non-linear resistor that conducts current exponentially with applied voltage, and only in one way
- A capacitor is a giga-ohm resistor with two electrodes that conducts through dielectric materials, it also happen to store charge too. 
- An inductor is a low-value resistor made with coils of copper wire wrapped around something, that also happens to store energy in the magnetic field.

Go ahead, replace all your schematic symbols with resistors.

If a p-n junction can be described as an resistor, they why not draw your pnp junction transistor as a few resistors too?

Go ahead, when your boss or client asks you to design a circuit, send them a page of resistors. Next time you buy a CPU for a PC, ask for a package of 1 billion integrated non-linear resistors too! See what you get.

The fundamental reason a resistor is a resistor, and a diode is not a resistor, is because we engineers decided it is just easier for everyone to agree on using terms to abstractly describe devices with different classes of expected behavior.

It is non productive to call everything "resistor, but non-linear", "resistor, but stores charge", "resistor, but inductive". We decided there's a line in the sand where we split all these "resistors" into different abstract things, giving them different names "diode", "capacitor", "inductor" while reserving "resistor" for the linear device we already understand it to be.

You can invent your own method of describing a circuit. You can invent your own mathematical system. You can invent your new language. We simply agreed on what we commonly use to get everyone on the same page, and not having to explain everything from scratch every single time.

[Berni]

They are not. The resistor is the industry standard term for a device that is designed to create the effect of resistance in a well defined manner. While electrical resistance is a physics phenomenon where something opposes the flow of current in a electrical circuit.

What is the point you are trying to make with this thread? That a diode has electrical resistance? Or that everything that exhibits electrical resistance should be called a resistor?

I am trying to uncover the roots of this cognitive dissonance. First you say that varistors are resistors that... And then you say no, they are not resistors, because resistors are only linear.

Go on that Vishay page that shows how to simulate nonlinear resistors (a term that up to a few messages ago you people thought I had invented, LOL) and simulated your resistor with an exponential characteristic. There you have your diode. It is a nonlinear resistor.

Yes a resistor that is designed to exhibit high nolinearity is called a varistor, this is to not confuse it with a regular resistor that is meant to have just a well defined resistance as the primary characteristic.

So this thread is indeed just about you not agreeing with how things are named.

I don't decide what the industry decides to call things. I just follow the already established naming conventions so that there is no confusion about what we are talking about to the majority of people in the field. The purpose of giving things names is to facilitate communication. Sure not all names for things are the best choice and sometimes they are obsolete historical reasons for the origin of a name, but it is what it is.

The laws of physics don't change if you change the name of a device. This thread shows that the vast majority of forum members agree upon what a resistor is and it also agrees with what Wikipedia defines as a resistor. So i am going to continue using that definition of a resistor as it clearly is the more prevalent industry standard.

Nothing really to gain from arguing about already established naming conventions.
So i am leaving this thread. See ya 

[ebastler]

Sheesh... how long do you guys plan to continue this?

"Resistor", without any qualifier, is used in practice to designate a component which exhibits ohmic resistance. Strictly speaking, one should use the term "ohmic resistor" for that type of component, and reserve the unqualified "resistor" as the generic term for ohmic and non-linear resistors. But in practice, nobody does that.

We also use special terms for non-linear resistors with specific properties -- diode, varistor, NTC, PTC etc. -- and don't refer to them as "resistors". Otherwise, confusion would ensue since "resistor" is so commonly used to refer specifically to ohmic resistors.

So Sredni is right, in a fundamentalist, "how many angels on a pinhead?" kind of way -- which seems to give him great satisfaction. But in practical terms, everybody else is right.

[magic]

From: A.C. Fischer-Cripps, in Newnes Interfacing Companion, 2002
3.3.7 Log amplifier
A non-linear resistor is connected into the feedback circuit. In practice, this can be a diode, but a transistor connected as a diode is used since the forward biased transfer function is more accurately exponential. The exponential nature of the forward biased diode leads to a logarithmic decrease in gain of the circuit as the input signal is increased.

Nonsense.

This circuit has almost linear decrease in gain as the input signal increases. Consider for example R1 = 1kΩ:

Vin = 1V, I = 1mA, Vout = -600mV, gain = -0.6
Vin = 2V, I = 2mA, Vout = -618mV, gain = -0.31
Vin = 5V, I = 5mA, Vout = -642mV, gain = -0.13
Vin = 10V, I = 10mA, Vout = -660mV, gain = -0.066

[DenzilPenberthy]

This thread is a truly dumb premise.  So what OP is saying is that literally every single electrical/electronic component that exists is a 'resistor' and that's somehow a useful or interesting observation?

Presumably OP would even pedantically call a superconductor a 'resistor' just 0 Ohms?

This is the same sort of person who spends the whole evening in the pub with friends strenuously arguing that breakfast cereal is a type of soup.

[Sredni]

There's no reason why you couldn't call every 2-leaded device as a resistor:

- A diode is a non-linear resistor that conducts current exponentially with applied voltage, and only in one way
- A capacitor is a giga-ohm resistor with two electrodes that conducts through dielectric materials, it also happen to store charge too. 
- An inductor is a low-value resistor made with coils of copper wire wrapped around something, that also happens to store energy in the magnetic field.

 

No.
Capacitors and inductors are FUNDAMENTALLY different from resistors. How many times do I have to repeat it? There are only four (three in practice) fundamental circuit elements: resistors, capacitors, inductors,(and memristors, but let's forget about them).

I mean, this is the basis of circuit theory.
It's all about what are the state variables that describe their behavior. All you need to describe the state of a circuit at any time are the values of charge q, magnetic flux phi and their derivatives, the current i=dq/dt and the voltage v=dphi/dt.

(Pure) Resistors are components described by a relationship in the V-I plane. If this relationship is a straight line they are linear resistors (but we call them just "resistors" for simplicity). If this relationship is not a straight line they are nonlinear resistors and depending on the particular shape of the characteristic they take many names such as incandescent lamp, varistor, diode, zener diode, tunnel diode, and so on.

(Pure) Capacitors are components described by a relationship in the q-V plane. If this relationship is a straight line they are linear capacitors (we call them "capacitors" for brevity). If the relationship is not a straight line they are nonlinear capacitors. You cannot describe the state of a capacitor by using the values V and I; you need v and the integral of I, that is charge.

(Pure) Inductors are components described by a relationship in the phi-I plane. If this relationship is a straight line they are linear inductors (and in introdoctury courses we call them "inductors" for brevity). If the relationship is not a straight line (because of saturation and hysterisis) they are nonlinear inductors (and we still call them "inductors" because they are very widespread, like the I in SEPIC).
You cannot describe the state of an inductor by just using the values of V and I; you need I and the derivative of V, that is the magnetic flux phi.

And before you say, if I give you the v(t) and I(t) functions I can still find the value of C and L, Think again: you need a function to extract information on the integral or derivative.

What is the value of a (linear) capacitor that has a voltage of 1 volt and a current of 1 mA? You can't find it. But if I tell you that when it has 1 volt across it, it's charge is 1 uC you will immediately tell me it's a 1uF capacitor.

So, no. You CAN'T call a (pure) capacitor a resistor because it is NOT a resistor.
This is the absolute bare minimum of circuit theory.

But you can call a (pure)diode a resistor because it IS a (nonlinear) resistor. Offering a voltage dependent resistance is what it FUNDAMENTALLY does. It's not a matter of naming, it's about it's findamental nature.

You can invent your own method of describing a circuit. You can invent your own mathematical system. You can invent your new language. We simply agreed on what we commonly use to get everyone on the same page, and not having to explain everything from scratch every single time.

You people should start read some books. This is NOT "my" method of describing circuits. This is not "my" language. This is how circuits are described in universities all over the world. It's just that not all textbooks join the dots for you.

[TopQuark]

This is stupid.

https://article.murata.com/en-global/article/insulation-resistance-and-leakage-current-of-capacitor

Capacitors can leak, dielectrics can conduct, it has a I-V curve at DC, so it could be resistive. Your pure, ideal capacitor in your head does not leak, but I look at all the capacitors in my parts storage, and all of them has a leakage current (I) when high enough voltage is applied to it (V). Should I relable it as all resistors?

(Pure) Resistors, (Pure) Capacitors, (Pure) Inductors

Resistance, capacitance, inductance are the words you are looking for. Those are the the theoretical physical properties that are well defined. Resistor, capacitor and inductors are the devices that does mostly what it says in the name, but we all know it isn't perfect. When I put a capacitor symbol in my schematics, I don't mean to spec in two magically floating metal plates separated by a perfect vacuum, I am placing a tube containing a couple strips of foil separated by paper soaked in electrolyte, a.k.a. an electrolytic capacitor on a PCB.

You can say a diode has resistance, which I am sure you can wrangle your math to proudly show it is so, fine, but that does not mean "an LED is a resistor". The ability to use maths and quote books to make pointless arguments proves you have linguistic intelligence, but it does mean not you are an intelligent person.

If you walk up to a straight dude, say he is gay, get punched in the face. You can argue "dude you are dumb, I saw you laughing, and according to the dictionary gay could mean happy, so I was correct. Did you even study English?". Who's the dumb one in this story? 

[Sredni]

I believe this is the sixth time I have to repeat it: in all this discussion I am neglecting parasitic effects. Because I am discussing the FUNDAMENTAL nature of the diode.

A silicon diode described by the exponential Shockley relation, with negligible junction capacitance and negligible inductance of its terminals is FUNDAMENTALLY just a nonlinear resistor, that is: a resistor whose resistance is a function of its voltage.
I also showed the R = R(V) curve in LTSpice.

It does nothing more than that. The nonlinear resistance is its primary and intended function. It is what it makes it a diode.
Unlike the ESR of capacitors and inductors, which is only an undesirable parasitics.