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2 Tone VerilogA signal source does not work in Harmonic balance

ChristophHoehn

Hi all,

I have a problem to get a Verilog-A signal source with two output tones to work in harmonic balance. So far my code looks more or less like this (deleted some calculations):

// VerilogA for 

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

module emulator(out,gnd);

output out;
input gnd;

electrical out,gnd,internal1,internal2;


real freq1,freq2,amp1,amp2;

parameter real  centerFreq = 70G;
parameter string fundname1 = "rf1";
parameter string fundname2 = "rf2";

analog begin

freq1 = 10M;

freq2 = 100M;

amp1=1;

amp2=1;

$cds_set_rf_source_info ( fundname1, centerFreq + freq1);
V(out,internal1) <+ (amp1)*sin(2*`M_PI*(centerFreq+freq1)*$abstime));
if (twoTargets>0)
begin
$cds_set_rf_source_info ( fundname2, centerFreq + freq2);
V(internal1,internal2) <+ (amp2)*sin(2*`M_PI*(centerFreq+freq2)*$abstime);
end
else
V(internal1,internal2) <+ 0;
V(internal2,gnd) <+ 50*I(internal2,gnd);

$bound_step(0.01/(centerFreq+freq1));
end
endmodule

With the help of a blog post I am able to make a signle source run in transient and Harmonic Balance. However when I try to use 2 sources harmonic balance will not calculate the correct results!

What am I doning wrong here? How to use $cds_set_rf_spurce_info() correct in my case?

Thanks in advance!

Parents

  • It appears to be a limitation that it doesn't work with two tones in the same VerilogA module. I've not found anyone else reporting the issue, so most likely nobody has tried doing this.

    Please contact customer support - this will need a change request to R&D to resolve, I believe.

    Andrew

  • in reply to Andrew Beckett

    Hi Andrew,

    thanks for the fast reply. I think I can work around with 2 verilogA cells. So this should be OK. However with that approach I still see weird Harmonic Balance behavior. Can it be true that HB Analysis has problems in the case the verilogA cell is not the first tone? I am working with a big LO cell and want to use the verilogA cells as tone2 or 3 in the HB analysis!

    Best

    Christoph

Reply
  • in reply to Andrew Beckett

    Hi Andrew,

    thanks for the fast reply. I think I can work around with 2 verilogA cells. So this should be OK. However with that approach I still see weird Harmonic Balance behavior. Can it be true that HB Analysis has problems in the case the verilogA cell is not the first tone? I am working with a big LO cell and want to use the verilogA cells as tone2 or 3 in the HB analysis!

    Best

    Christoph

Children
  • in reply to ChristophHoehn

    Hi Christoph,

    It's quite possible that it simply doesn't work currently with any more than one such tone - I think you really will need to follow this up with customer support (sorry, didn't have time to check myself - I did try your code the other day before replying before though, and tried to workaround it to no avail).

    Andrew

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