noisefile in a vdc source modeled by Verilog-A

Aldo,

How about this code below. A simple command line testcase would be:

// noise_from_file.scs

I1 (n1) noise_from_file filename="noise.dat" //debug=1
r1 (n1 0) resistor r=1k isnoisy=no

ahdl_include "noise_from_file.va"

noise (n1 0) noise start=1 stop=1G dec=10

With this as the noise.dat:

1e3,1e-9
2e3,2e-9
10e3,1.8e-9
1e6,2.2e-9

`include "disciplines.vams"

module noise_from_file (op);

output op;
electrical op;
integer mcd,count,retval;
real frq,val;
parameter string filename="noise.dat";
parameter maxpoints=100;
parameter debug=0;
real noisetab[0:maxpoints-1];

analog begin

   @(initial_step) begin
      mcd=$fopen(filename,"r");
      retval=2;
      count=0;
      while(retval==2) begin
	  retval=$fscanf(mcd,"%f,%f",frq,val);
	  if (debug) $debug("Data is %d %g %g",retval,frq,val);
	  noisetab[count]=frq;
	  count=count+1;
	  noisetab[count]=val;
	  count=count+1;
      end
      $fclose(mcd);
    end

    V(op) <+ noise_table(noisetab);
end

endmodule

Regards,

Andrew.

 Many thanks, Andrew

Regards,

Aldo

Hi Andrew,

Starting from your suggestions I wrote the following code:

module TEST(VOUT,ADJ);
    inout      VOUT, ADJ;
    electrical VOUT, ADJ;

    integer    voutPar,file,i,retVal;
    real       vthr,noiseFrq,noiseVal,voutVal;
    string     filename,temp;
    real       noisetab[0:1000];

    analog begin
        vthr=0.1;
        if(V(ADJ)>vthr) voutPar=1;
        else voutPar=0;
        case (voutPar)
            0: begin
                   filename="TEST_1V.csv";
                   voutVal  =1;
               end
            1: begin
                   filename="TEST_2V.csv";
                   voutVal  =2;
               end
        endcase
        file=$fopen(filename,"r");
        $fscanf(file,"%s",temp);
        $display("%s",temp);
        i=0;
        retVal=$fscanf(file,"%f %f",noiseFrq,noiseVal);
        while(retVal==2) begin
            noisetab[i]=noiseFrq;
            i=i+1;
            noisetab[i]=noiseVal;
            i=i+1;
            retVal=$fscanf(file,"%f %f",noiseFrq,noiseVal);
        end
        $fclose(file);
        V(VOUT) <+ voutVal+noise_table(noisetab);
    end
endmodule

 If voutPar=1, I get the following error message:

Internal error found in spectre during DC analysis `dcOp'. 
Encountered a critical error during simulation. Submit a Service Request via Cadence Online Support, including the netlist, the Spectre log file, the behavioral model files, and any other information that can help identify the problem.
    FATAL (SPECTRE-18): Segmentation fault.

Whereas if voutPar=0 it works.

If I make load the same file in both cases:

case (voutPar)
                0: begin
                       filename="TEST_1V.csv";
                       voutVal  =1;
                   end
                1: begin
                       filename="TEST_1V.csv";
                       voutVal  =2;
                   end
            endcase

the code works

Thank you

Best regards

Aldo