• 1ns when the voltage rises from 0V to 10V
• 24.5us when the voltage sits at 10V
• 1ns when the voltage falls from 10V to 0V
• 50u-24.5u-1u-1u = 23.5us when the voltage sits at 0V

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You should search the group archives yourself first. Those are the files with 'z-xxx' names on the Files web page. Also, look in the Examples that come with the app, and the Wiki.

Are there any files, messages etc, that detail how to plot the IP3 of an rf amplifier using LTspice?? I would be interested in comments and examples on this subject.

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I am not sure whether some of my libs got corrupted, but with the latest LTspice release and its stronger syntax check ie. the Bordodynov lib shoots huge number of errors which must be corrected otherwise the simulation does not start.

Usually errors are with TABLE syntax, but with typos as well (well, quite huge amount).

Any experience with that here?

The devs would probably argue that your libraries haven't been corrupted, but always failed "correct" syntax previously. Anyhow, this has already been discussed here at length, and there has been a flurry of new updates to the 24.1 branch as a result.

If you don't want to go through "fixing" all your "broken" libraries in the meantime, you could downgrade to V24.0.12. This is not on ADI's website, but a verified "Wayback" link to it has been published on here recently.

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Inside each .model there will definitely be default values stored somewhere, which could be returned if one is not provided explicitly in the .model statement, so I don't see why this couldn't be done. LTSpice is great for how it handles arbitrary expressions and behavioural devices, so I'm sure it would be possible to do such a thing if the developers wanted to.

Many things are possible. Default parameter values for LTspice, at least, are listed in the Help, so you could create your own default intrinsic models if you wished - put them into the standard.xxx libraries. I think LTspice uses the last same-named model it encounters. In any event, I petty sure they cannot be accessed programmatically internally, although it would straightforward to do externally. Unfortunately, LTspice cannot invoke arbitrary external code. Many years ago, long before its acquisition by ADI, LTspice had features that were used internally by LTC, but not documented or even acknowledged. Some were completely removed after being "discovered", or at least hidden more deeply, similar to the binary format of proprietary models that are supplied, but cannot be read. You need to remember that LTspice is proprietary software. If you want a SPICE that you can customise, Ngspice is open source - you could add features of your own to your heart's content. Similarly, the original SPICE code from Berkeley is public domain and freely available - an "up to date" buildable version for Linux can be found here:

I've no doubt it could be done in LTspice, but unless it's facilitated by one of the other ongoing enhancements to V24.1.x, good luck wishing for it. AFAIK, no one has ever requested it.

At least for now, you're stuck with a workaround.

--
Regards,
Tony

Thank you so much for taking the time to help me. I truly appreciate it.?
Can you please tell the purpose of ADuM3190-chip . this circuit is quite complex for me to understand as I am undergraduate student . how did you give pulse to mosfet surely from UC3875 gate driver but how you put PULSE command i can't understand how did you manage the switching frequency? at 30kHZ? can transformer work without this ADuM3190-chip?. .
Also i want to make the PCB of this circuit in KICAD software if you have any idea how can i design this transformer do i have to place the ADuM3190-chip in my pcb??

Thanks in Advance?

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1. The ADuM3190-chip was used to regulate the DAB-Converter. Open the datasheet to see what is inside the chip. This chip is operating much more linear, compared to other regulator configurations, such as

the combination of "voltage reference, together with an OP-Amp + Optocoupler". The optocoupler is known for it's nonlinearities and therefore more complicated to stabilize the converter.

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?? ?I just used the ADuM3190-chip to show an alternative solution. Its use is not mandatory, you don't need it.

????????

It is assumed you want to use the Transformer for isolation purposes, right?

In that case the regulation feedback loop needs to have an isolation as well.

Another alternative, for which an isolated regulation loop can be omitted, is the use of an isolated transformer-coupled Driver. In that case you will have the freedom to put the regulation circuitry to any ground point

- output Ground for instance - without the need for an isolated feedback loop. The isolated Driver provides a floating Ground. So, the regulator inside the UC3875 could be directly used for regulation.?

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2. The UC3875 gate driver outputs A,B and C,D can drive a transformer coupled driver or a Low side/-High side driver instead. For simplicity, I used voltage-dependent-voltage sources, which LTspice offers in its library as "e-sources". The switching frequency is accomplished by the R12,C8, connected to the FREQSET-Pin of the UC3875. For more information, pls refer to the datasheet, in which you find a curve for Rt=f(CT, frequency).

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3. The transformer(s) have nothing to do with the ADuM3190-chip at all.

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4. I can't assist you regarding KICAD. As mentioned above, ADuM3190-chip is not mandatory.

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5. For transformer design, pls refer to the following articles

? ? ? ?

and

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best regards

Udo

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Thanks for the reply. I already know how to create a parameter and use this value in a .model statement of transistor / diode etc, which is what you have shown, but unfortunately this doesn't help with my question.

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Is there a way to access a value defined in the .model statement of a transistor etc, and then use that value elsewhere in an expression?

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Is there some syntax like: "getvalue(npnmodel, is)", or "npnmodel.is", or something similar to grab the already defined value out of a .model statement?

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I scoured the LTSpice docos / online resources but and can't find anything like this, so I am guessing the answer is no, but I thought I'd ask here for an more official "no". I can workaround it in other ways, but having this sort of access would be really useful to prevent a bunch of manual text editing every time I want to try out a different model and calculate derived expressions from it.

I think your guess is correct. This isn't an "official "no". But since the Gummel-Poon model, for example, is public domain, it would in principle be possible to derive it from the actual characteristics. There is another issue: in most models, some of the parameters are not stated, so remain at their default value, which is often zero, but not always. Therefore they couldn't be extracted from the .model. I don't know for sure, but it's also possible that not all simulators have the same default values. I would think this is enough to deter you from this route, and probably why such a reverse look-up doesn't exist.

--
Regards,
Tony

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I'm creating some subcircuits and would like to use some parameters of a model in further expressions, but only have to define the value once in the model itself. Is this possible in LTSpice? For example can I use the saturation current of a particular transistor model in a subsequent expression? eg:

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* define a model with some parameters

.model npnmodel npn(is=1e-16 n=1.02)

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* access one of the parameters in an expression somehow to calculate a derived value

* - the actual expression will be more complicated than just *2

.param val = {npnmodel(is)*2}

If I understand you correctly - yes, this is possible. But rather than try and describe it, I have uploaded one available solution - undoubtedly, there are others.

Param-to-subckt-to-model

BTW, it is not necessary to use braces when assigning a numeric value to a parameter.

• Position the cursor over one end of the resistor so that the probe turns red.
• Press and hold the left mouse button.
• Move the cursor to the other end of the resistor until the probe turns black.
• Release the mouse button.