If I use QSpice to create a new symbol, How do I associate a schematic below that symbol?

QSPICE
1

If I use QSpice to create a new symbol, How do I associate a schematic below that symbol?

2

There are two types of custom symbols: subcircuit symbols and hierarchical symbols. What you are referring to is a hierarchical symbol that links to a schematic file (.qsch).

Refer to this post to see if it answers your question.
Subcircuit schematic designator - QSPICE - Qorvo Tech Forum

I have a complete study documented in Part 2 of this general guideline
General Reference Guide by KSKelvin.pdf - KSKelvin-Github

3

You mentioned the tunnel diode symbol in another thread. Here is an example using a subcircuit symbol to obtain a model from an external library file.

example.TunnelDiode.1N2927.qsch (41.8 KB)
Tunnel Diode Library - Bordodynov.txt (1.2 KB)

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image1106×527 41.5 KB

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Where do I find that external library file?

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How do I obtain this pdf Guide? Clicking on the reference above gives an error message about invalid file

6

Well… it’s interesting that the answer to your question is not that far away.

  • If you open the library file, I have marked where I found this netlist—in a discussion thread on the LTspice discussion forum. Bordodynov is one of the key members currently in this forum.

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    image960×126 10.5 KB

  • You can download the file from Github by clicking this icon, or you can clone the repository.

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    image1479×311 15.8 KB

7

Thank you…I think that I forgot to check the bottom of my screen.

8

I have not been able to download your General Reference Guide

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Please attempt once more. I have just tested it and did not encounter any issues downloading items from Github. Is it possible that an antivirus program is blocking your downloads from the internet?

10

Error rendering embedded code

Invalid PDF , above is the error message that I get when attempting to download your guide.

11

I had no issue downloading the tunnel diode ckt and model files above.

12

Verified with two laptops and confirm with another forum member, no issue can be observed in downloading this pdf from Github. Just hit this download icon in regardless the pdf can load in your browser or not. I waited several seconds and a download will initiate. OR, try other internet browser or computer? This is the first time I got a report that file cannot be download from Github. Or, install Github desktop and clone my repository.

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image1471×809 86.5 KB

Well… another method is that, change /blob/ to /raw/ in download link, this will kick a direct download. Here is changed link
https://github.com/KSKelvin-Github/Qspice/raw/main/Guideline/Qspice%20-%20General%20Reference%20Guide%20by%20KSKelvin.pdf

13

Thank you, I finally got the General Reference Guide from above.

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Also, thank you for the tunnel diode library file. I have learned a lot from studying those models some of which I am able to modify for my needs. I am trying to simulate the multi-tunnel diode trigger circuit in the 5T3 timing plugin for the Tektronix 661 sampling scope. Sometimes Qspice gets stuck with timestep too small indications. Does you guide offer any advice on that?

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I didn’t know about tunnel diode before this October in supporting this post (How to generate piece-wise linear multi-peak resonant tunneling diode model - QSPICE - Qorvo Tech Forum)

Well… I can understand why this I-V relationship can pose a challenge, as a single current value can result in multiple voltage solutions. If, in any case, the simulation attempts to determine the node voltage from the current value, the solving process may jump between different solutions and be unable to converge on a solution, resulting in a timestep that is too small.

Anyway, I believe it is very challenging to integrate this I-V relationship into a complex circuit. Having a single V-source to obtain its I-V is simple. However, anything more complex may become entangled in its characteristics. Just my thoughts on this topic.

16

Thanks for referencing the piece-wise linear tunnel diode above. I am not interested in multiple Tunnel diodes in series, but just one. The piece-wise linear Tunnel Diode lends itself to easily set the peak and valley points as well as both slopes…very handy and seems to simulate well even with multiple Tunnel Diodes in the simulation like in the trigger section of he Tektronix 5T3 timing unit in the trigger section of the Tekronix 661 equivalent time sampling scope.

17

It would be great if you could share an application example of a tunnel diode. I have no idea what applications would be interested in this I-V characteristic.

I upload the RTD piecewise linear symbol in here
Qspice/Symbols-KSKelvin/devices/others/RTD.qsym