Talk:Diode modelling

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This article really needs to follow the Wikipedia:Manual of Style - JustinWick 03:00, 21 February 2006 (UTC)[reply]

I think it does a good job of explaining the modelling of a diode. I'm not sure what sort of style changes are being called for, but I think the explanatory nature of the article is helpful and is generally used in textbooks. Accountable Government 03:59, 2 March 2006 (UTC)[reply]

The integrity of the article seems fine, however I added subsections and a contents box to improve the formatting. If it's okay, could someone remove the "formatting and style" box. Cheers Dom 17:42, 5 January 2007 (UTC)[reply]

Article todo

Glad to see this article is coming along. Here are a few issues that I think may need addressing:

The article sounds a bit too informal. Some parts may need to be re-written to sound more "encyclopedic".
~~I_D >> I_s seems like a better condition than V_d >> nkT/q for neglecting the - 1 term in the Shockley model.~~
~~Also nkT/q is usually written as just V_T.~~
The plots should be redone as .png's to avoid artifacts
The schematics could probably be redrawn as well.

-Roger 21:04, 8 November 2007 (UTC)[reply]

plots and schematics are even better drawn as .svg so they can be viewed at any resolution. Em3rgent0rdr (talk) 18:09, 6 July 2023 (UTC)[reply]

Lambert W

Good addition, but Maple did it first. --165.21.155.92 (talk) 08:55, 13 January 2008 (UTC)[reply]

Threshold Voltage

This article continues the myth that there is a Threshold Voltage in the forward V/I curve, however as the curve is essentially an Exponential, there can be no threshold, ie the rate of change is smooth and continuous, there is no elbow. Draw it on a Log scale and the "elbow" disappears. The idea of an Offset Voltage comes from a simple piece-wise approximation that is taught to students and technicians, but is then taken as gospel. The Threshold Voltage does not in fact exist. Gutta Percha (talk) 06:59, 17 September 2013 (UTC)[reply]

For a power supply, low impedance is the paradigm. With low impedance blinders on maybe the threshold voltage myth has little impact. For small signal applications, the notion that a diode has a threshold voltage is a critical misunderstanding. Would someone with technical understanding of diodes and writing skills please start a new section that addresses this. 65.209.92.126 (talk) 16:28, 23 September 2013 (UTC)[reply]

Indeed the "knee" or "elbow" is simply an illusion when plotted in a particular linear scale. If the vertical range is changed, then the "knee" shifts...a good animation of this is: https://www.abarry.org/knee.htm

On the other hand, in practice, a particular circuit may have some "typical" current range. If some arbitrary number of milliamps can be treated as the point of "significant-enough" conduction, then a diode will have a particular voltage drop that doesn't change by much when the current changes a little. That makes for a simplified infinite step model of a diode's I/V curve. And using such a simplified model can greatly facilitate quickly analyzing circuits. So in practice the concept of a diode having a "threshold voltage" is useful even though in theory and in truth a diode doesn't have a threshold voltage.

Em3rgent0rdr (talk) 18:04, 6 July 2023 (UTC)[reply]

Let's not use the word "ideal" to describe diode approximations other than the "Shockley ideal diode equation"

The word "ideal" to describe a diode can be very ambiguous. For one, we have the exponential Shockley diode equation which is sometimes called the "Shockley ideal diode equation" with its ideality factor n equals 1. But however this article currently describes a "Mathematically idealized diode" as to be something *very* different:

Mathematically idealized diode
[edit]

I-V characteristic of an ideal diode.

Firstly, consider a mathematically idealized diode. In such an ideal diode, if the diode is reverse biased, the current flowing through it is zero. This ideal diode starts conducting at 0 V and for any positive voltage an infinite current flows and the diode acts like a short circuit. The I-V characteristics of an ideal diode are shown below:

And then later in this same article it describes a couple variants that use this "ideal" diode as a starting point.

I would suggest that this article refrain from using the word "ideal" unless it specifically is talking about the "Shockley ideal diode equation", to avoid confusion.

So this section "Mathematically idealized diode" should instead be called "infinite step response diode approximation"? Because what it really looks like is the Heaviside step function multiplied by infinity. Em3rgent0rdr (talk) 17:34, 6 July 2023 (UTC)[reply]

Doubtful assertion

QUOTE: "For large x, $W(x)$ can be approximated by $W(x)=\ln x-\ln \ln x+o(1)$ . For common physical parameters and resistances, ${\frac {I_{S}R}{nV_{\text{T}}}}e^{\frac {V_{s}}{nV_{\text{T}}}}$ will be on the order of 10⁴⁰."

No it won't be, on the contrary. By quick calculation, with $I_{S}=$ 1nA, $R=$ 10 ohm, $V_{S}=$ 0.7V, $n=$ 2, $V_{T}=$ 25.3mV</math> we get $x\approx$ 0.2

Please either remove the assertion, or find a better example that works. Apparently, the logarithmic approximation of $W(x)$ cannot be used to calculate diode current with series resistance at a practical value, such as a few ohms. Morycm (talk) 22:08, 18 September 2024 (UTC)[reply]