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VHDL AMS and LTF

Hi,

I'm trying to simulate a simple opamp model which is written in VHDL AMS. Unfortunatly the AMS Simulator does not simulate it and produces the following error:

Analog Kernel using -ANALOGCONTROL ./amsControlSpectre.scs.
Reading file:
        /.../netlist/amsControlSpectre.scs
ncsim: *E,EUNLTF: /.../vhdl.vhms:101: vin'LTF_101_15: The parameters of the LTF attribute must be aggregates of scalars.

Error found by spectre during circuit read-in.
    ERROR (SPECTRE-357): AMS Analog Elaboration has exited with error.
        Simulation will terminate.

The corresponding part of the model looks as follows (wP1, wP2 and gain are real generics):

constant num : real_vector := (0 => wP1 * wP2 * gain);
constant den : real_vector := (wP1 * wP2, wP1 + wP2, 1.0);
vout == vin'ltf(num, den);

Are their any ideas in how to resolve this error?

mschw over 7 years ago

Have you tried

vout == vin'ltf((0 => wP1 * wP2 * gain), (wP1 * wP2, wP1 + wP2, 1.0));

?

Kind regards,

Matthias
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mschw over 7 years ago in reply to mschw

I think that my upper suggestion will not work either. You might take a look in the Cadence VHDL-AMS Overview . There, the use of LTF Systax is explained exactly (Section Examples of Attribute Use: Q'ltf)

Kind regards,

Matthias
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LukiLeu over 7 years ago in reply to mschw

Hi mschw

Your suggestion without the constants is working. The question is just why? However I can live with that solution. Where can I find the Cadence VHDL-AMS Overview, I wasn't able to find it...

Thank you

Lukas
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mschw over 7 years ago in reply to LukiLeu

Dear Lukas,

you can find the Cadence VHDL-AMS Overview in the Cadence Installation directory /doc/vhdlamsov/vhdlamsov.pdf or here .

I suppose since the LTF syntax requires aggregates of scalars a array reference cannot be used.

Kind regards,

Matthias
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