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Pulse source in Verilog-A(MS) (Read 3150 times)

nvs117

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Posts: 2
Germany

Pulse source in Verilog-A(MS)
May 08^th, 2007, 7:09am

Hi there,

What are the possibilities to model a source which gives a rectangular voltage (or position) pulse at a certain time point?

I have tried this here, but this is doesn't give the right result - it always produces large outputs (either below or greater zero).

BTW: Don't hesitate, this is a signal-flow approach! Wink

// position pulse

module pos_pulse (out_pos);

parameter real startval = 10.0;
parameter real endval = 0.0;
parameter real period = 100.0;
parameter real starttime = 1.0;
parameter real endtime = 15.0;

output out_pos;
position out_pos;

analog begin

@(initial_step) begin
Pos(out_pos) <+ slew(startval, 1.0e-9, 1.0e-9); // also tried "transition" here
end

@(timer(endtime)) begin
Pos(out_pos) <+ slew(endval, 1.0e-9, 1.0e-9); // also tried "transition" here
end
end
endmodule

Any ideas?

Chris

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Geoffrey_Coram

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Posts: 1998
Massachusetts, USA

Re: Pulse source in Verilog-A(MS)
Reply #1 - May 8^th, 2007, 12:06pm

nvs117 wrote on May 8^th, 2007, 7:09am:

@(initial_step) begin
Pos(out_pos) <+ slew(startval, 1.0e-9, 1.0e-9); // also tried "transition" here
end

I don't think this is legal syntax ... you shouldn't have <+ nor slew inside an event. Instead, you should have a real value that gets set in the events, and the contribution should be performed always:

real outval;
@(initial_step) outval = startval;
@(timer(endtime)) outval = endval;

Pos(out_pos) <+ transition(outval, 1n, 1n);

If at first you do succeed, STOP, raise your standards, and stop wasting your time.

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nvs117 New Member Offline Posts: 2 Germany	Re: Pulse source in Verilog-A(MS) Reply #2 - May 9^th, 2007, 3:59am Hi Geoff, This works fine. Thanks from a VAMS newbie. ;-)
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