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Design Languages >> Verilog-AMS >> error when adding 2 variables
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Message started by Pavel on Apr 17^th, 2007, 12:29am

Title: error when adding 2 variables
Post by Pavel on Apr 17^th, 2007, 12:29am

Hello,

When modelizing fully differential OTA I've met strange error from veriloga parser.

Here are 2 variables that modelize output small-signal behavior

Code:

V1P_AC = Gain_AC * laplace_nd(vin_dif, zeros, poles);
V1N_AC = Gain_AC * laplace_nd(-vin_dif, zeros, poles);

and here is common mode processing

Code:

V1_CM = Gain_CM * laplace_nd(V(Vbpfb), zeros, poles);

Then I add common-mode part with small signal part to form outputs:

Code:

V1P = V1P_AC + V1_CM;
V1N = V1N_AC + V1_CM;

When I compile this code, following error appears:
Error: dynamic quantities must be directly accessible to the outputs.

What does this error mean?

Regards

Pavel.

Title: Re: error when adding 2 variables
Post by Pavel on Apr 17^th, 2007, 12:40am

Sorry, the error message concerns portion of code that follows:

Code:

// Slew-Rate processing
@(above(SLEW_RATE - ddt(V1P))) slew_rate_P = 0;
@(above(SLEW_RATE - ddt(V1N))) slew_rate_N = 0;

@(above(-SLEW_RATE + ddt(V1P))) begin
slew_rate_P = 1;
i_max_P = I(OutP);
end

@(above(-SLEW_RATE + ddt(V1N))) begin
slew_rate_N = 1;
i_max_N = I(OutN);
end

Regards

Pavel

Title: Re: error when adding 2 variables
Post by Pavel on Apr 17^th, 2007, 1:04am

Resolved - for slew rate processing I employed slew function.

Regards

Pavel