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Design Languages >> Verilog-AMS >> cannot recognize Spectre primitive "diode"
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Message started by Pavel on Jan 2^nd, 2007, 6:06am

Title: cannot recognize Spectre primitive "diode"
Post by Pavel on Jan 2^nd, 2007, 6:06am

Hello

ncelab cannot recognize diode instantination.

My instantiation looks like this

diode D1 (A, B);

After elaboration I see the following message in HE window:

ncelab: *E,CUCFUN: instance 'D1' of the unit 'diode' is unresolved in 'PROJ.SCH:verilogams'.

but diode is Spectre primitive like resistor or capacitor.

Why the last two primitives are recognized, but diode - not.

Regards.

Pavel.

Title: Re: cannot recognize Spectre primitive "diode"
Post by Geoffrey_Coram on Jan 2^nd, 2007, 8:09am

Per theVerilog-AMS LRM, diode (as well as jfet, mosfet, bjt) require the use of a .model card in most Spice simulators, and thus you can't instantiate them directly. Resistor and capacitor are allowed, not because they are Spectre primitives, but because the LRM says that these Spice primitives shall be recognized by the Verilog-AMS simulator.

I don't know how you get a model card into your circuit. It's outside the LRM, in terms of how you direct your particular simulator to read spice/spectre library files.

Title: Re: cannot recognize Spectre primitive "diode"
Post by Pavel on Jan 3^rd, 2007, 1:16am

Geoffrey,

Thank you for hint. I found it. In Cadence-AMS design flow one can include models
using AMS plug-in of Hierarchy Editor (HE->AMS->Analog Models...).
But I found only our technology specific models (with names that differ from ones from Spectre device manual).
I don't know where are situated generic models.

Regards.

Pavel.

Title: Re: cannot recognize Spectre primitive "diode"
Post by Geoffrey_Coram on Jan 4^th, 2007, 5:39am

Can you make up your own models? Eg, look at how the technology-specific models are added in and add a pointer to a local file that defines your own model.

In Spectre format, something like:
model mydio diode
is probably sufficient; you can add is, cjo, etc. when you're ready.

Title: Re: cannot recognize Spectre primitive "diode"
Post by Pavel on Jan 9^th, 2007, 6:33am

I found only models based on diode or bsim3v3 (for semiconductors).
But if we see Spectre manual, we could find about 15 different mos models.
My question is just for curiosity: if exist somewhere in Cadence installation some directory with all generic models,
enumerated in Spectre manual.

Regards.

Pavel.

Title: Re: cannot recognize Spectre primitive "diode"
Post by ACWWong on Jan 9^th, 2007, 9:38am

Doing spectre -h components will give you all the list of available built in models.
Doing say spectre -h diode will give you all the default parmaters for a diode. you can do the same on the other components.

In spectre you can just add a blank model file, and it'll pick up the default values.
so you could create mydiodemodels.scs which is uses default values with:

model modelName diode

cheers
aw

Title: Re: cannot recognize Spectre primitive "diode"
Post by Andrew Beckett on Jan 17^th, 2007, 10:34pm

There are a bunch of sample model files in:

<ICinstDir>/tools/dfII/samples/artist/models/spectre

but none for diodes.

Also, look in:

<ICinstDir>/tools/dfII/samples/artist/spectreExamples

there are some diode models in some of the underlying examples (look in the files in the detector subdirectory).

Regards,

Andrew.