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Design Languages >> Verilog-AMS >> idt() function in hspice simulator
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Message started by neoflash on Oct 23^rd, 2010, 11:37pm

Title: idt() function in hspice simulator
Post by neoflash on Oct 23^rd, 2010, 11:37pm

I used idt() function in hspice simulator for a VCO.

However, I got trouble that sometimes the idt() output result may jump erroneously.

Is there any option that I can help with this issue?

Title: Re: idt() function in hspice simulator
Post by Marq Kole on Nov 17^th, 2010, 6:36am

You will need to provide a little more information if you want us to help you.

Anyway, when you mentino VCO I would suggest you have a look at the idtmod() operator instead of the idt() operator.

Cheers,
Marq

Title: Re: idt() function in hspice simulator
Post by neoflash on Nov 17^th, 2010, 11:58am

Marq Kole wrote on Nov 17^th, 2010, 6:36am:

idtmod() works much better and solves the problem. Thanks.

Title: Re: idt() function in hspice simulator
Post by neoflash on Nov 20^th, 2010, 3:28pm

finesim doesn't support this special idtmod() function. sucks.

Title: Re: idt() function in hspice simulator
Post by Marq Kole on Dec 8^th, 2010, 8:12am

Hi,

That's weird - I'm using finesim 2010.08.00 and the code below runs just fine:

Code:

`include "disciplines.vams"
`include "constants.vams"

module va_vco2 (out, ctrl, ref);

parameter real amp = 1;
parameter real minfreq = 1M;
parameter real gain = 1.2M;

inout ctrl, out, ref;
voltage ctrl, out, ref;

real phase, freq;

analog begin
freq = minfreq + gain * V(ctrl, ref);
phase = `M_TWO_PI * idtmod(freq, 0, 1);

$bound_step(0.1 / freq);

V(out, ref) <+ 0.5 * amp * (cos(phase) + 1);
end

endmodule

Are you using a recent version? We have no trouble with the Verilog-A support of finesim.

Cheers,
Marq

Title: Re: idt() function in hspice simulator
Post by neoflash on Dec 8^th, 2010, 12:11pm

We are using the most recent version.