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I am trying to model diode characteristic curve, But cannot simmulate the knee voltage, or the breakdown voltage.

Is it possible to do so?

I am using the Student version.

regards waqar shahid

Here is the link to my circuit

https://www.circuitlab.com/circuit/kb843s/diode-characteristics/

I'm not the best with diodes. For starters I don't think CL dose break down voltage, which I can understand because it may have different unpredictable characteristics after being in that region. But I could get a 'Knee voltage' when I simulated your circuit from -1V to 3V with a step size of 0.01V.

Yes, knee voltage is OK

Thanks

Garrett is right; CL does not model reverse breakdown voltage.

Most vendor-supplied spice models for simple diodes include a reverse breakdown voltage parameter (BV) but CL is not a spice simulator and, as already mentioned, does not support the BV parameter so reverse breakdown cannot be modelled directly in a CL diode.

For a bit more background to CL's diode models ...

https://www.circuitlab.com/browse/by-tag/parameter-sweep/

https://www.circuitlab.com/forums/analog-design/topic/t4v8kpa2/diode-characteristic-curve/

and ...

About datasheet, device and simulation model parameters

SPICE parameters for devices have little to do with datasheet specifications. They are much more to do with semiconductor physics and the particular process under which a given device is manufactured at the foundry. Consequently it is not always a simple task to map datasheet information onto the model parameters.

So ... what you can do is trawl manufacturers websites for a diode spice model for your target diode

From there you pilfer the parameters that you can use in the CL model and set up the CL model using them (Edit parameters > Edit individual parameters).

In the background, build a diode test jig like the one in this lively little thread:

https://www.circuitlab.com/forums/analog-design/topic/t4v8kpa2/diode-characteristic-curve/

to sanity check your CL diode against its original datasheet.

If you want to try to understand more about what the SPICE - and hence CL - parameters mean in diodes, bipolar transistors and MOSFETs, then you might like to have a look at:

http://www3.imperial.ac.uk/pls/portallive/docs/1/56133736.PDF

with individual slide sets:

http://www3.imperial.ac.uk/pls/portallive/docs/1/7292571.PDF

http://www3.imperial.ac.uk/pls/portallive/docs/1/7292572.PDF

http://www3.imperial.ac.uk/pls/portallive/docs/1/7292573.PDF

For more detailed information about bjt's in particular, have a look at this book:

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01480193

available from:

http://www.lulu.com/spotlight/iangetreu

and

http://www.amazon.com/Modeling-Bipolar-Transistor-Ian-Getreu/dp/B000EYPQLU

Another excellent (and free) book about transistor modelling, go to:

http://www.aeng.com/spice_modeling.htm

and register to get a copy of:

Definitive Handbook of Transistor Modeling

However, if you can find a spice model for your target device, then you can edit the relevant parameters of one of the built-in CL models and use that in your circuit.

For more information please see this thread:

https://www.circuitlab.com/forums/basic-electronics/topic/9dg62j8d/help-for-beginners-hobbyists/

Note that there are some unanswered questions about editing CL model parameters (which may not affect you anyway):

https://www.circuitlab.com/forums/feature-requests/topic/6k7v65fx/questions-about-editing-model-parameters/

This thread has several links to more about spice diode parameters:

https://www.circuitlab.com/forums/modeling-and-simulation/topic/4jex93sw/importing-transistor-from-datasheet/#comment_2309