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 abrup jump in step response of analog LPF  

Last post Thu, Apr 26 2012 1:49 AM by nzborsti. 0 replies.
Started by nzborsti 26 Apr 2012 01:49 AM. Topic has 0 replies and 460 views
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  • Thu, Apr 26 2012 1:49 AM

    • nzborsti
    • Not Ranked
    • Joined on Thu, Mar 29 2012
    • Posts 6
    • Points 30
    abrup jump in step response of analog LPF Reply
     

    Hello there,

    I wrote a Verilog AMS Modle for a simple analog LPF:

    //Verilog-AMS HDL for "test", "filter2" "verilogams"

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

    module filter2 ( in, out);
    input in;
    output out;
    electrical in,out;

    parameter real tau1= 0.66 from (0:inf);
    parameter real tau2= 0.074 from (0:inf);
    real Kn;  


    // passive filter lead lag

    analog begin

    Kn=tau2/(tau1+tau2);

    V(out)<+Kn*laplace_nd(V(in), {1/tau2,1},{1/(tau1+tau2),1 });

    $bound_step(1n);

    end

    endmodule

    When I looked closer at the step response of the filter I saw that there is a abrupt jump in the output signal at the time where the step is applied to the input. That is a bit strange since the output should be continious. Does anyone know what's going wrong here? I am using AMS  solver in ADE XL.

    Thanks for your help.

     

    • Post Points: 5
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Started by nzborsti at 26 Apr 2012 01:49 AM. Topic has 0 replies.