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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	idt() function in hspice simulator 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?
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Marq Kole Senior Member Offline Hmmm. That's weird... Posts: 122 Eindhoven, The Netherlands	Re: idt() function in hspice simulator Reply #1 - 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
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neoflash

Community Fellow

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Mixed-Signal
Designer

Posts: 397

Re: idt() function in hspice simulator
Reply #2 - Nov 17^th, 2010, 11:58am

Marq Kole wrote 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

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

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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: idt() function in hspice simulator Reply #3 - Nov 20^th, 2010, 3:28pm finesim doesn't support this special idtmod() function. sucks.
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Marq Kole

Senior Member

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Hmmm. That's
weird...

Posts: 122
Eindhoven, The Netherlands

Re: idt() function in hspice simulator
Reply #4 - 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

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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: idt() function in hspice simulator Reply #5 - Dec 8^th, 2010, 12:11pm We are using the most recent version.
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