Spectre and Simulink cosimulation - Problem on defining cosimulation inputs

Hi Milad,

I don't think this is really possible. You could of course use some kind of voltage-controlled resistor or capacitor (a vccr can be a voltage-controlled resistor, for example) and do it that way.

If you only want to optimise the component values once for each simulation, you'd be better off having Matlab create some include file with parameter values that the main netlist could reference. Something like that.

Regards,

Andrew.

Dear Andrew,

    Thanks for your reply. It's really surprising for me. I hope the interface "SpectreRF Engine", with all these huge tasks, be able to consider any other inputs on the next versions.

    Fortunately, I've just done a successful optimization using a direct approach (not using the interface). I'd like to share the MATLAB script here to be useful for the other users with the same problem:

    It is a circuit with a dc voltage (1 volt) and two series resistor (R1=1k and R0=?). The optimization is going to find the value of R0 in order to have V0 = 0.5 volt.

function [P] = lsqspectre     % lsqspectre demonstrates using fminbnd with spectre.

Var = fminbnd(@tracklsq, 10, 2000);

P = Var;

function F = tracklsq(Var)

% Track the output of input.scs to a signal of 0.5

P = Var;

% Read input.scs into cell A
fid = fopen('input.scs','r');
i = 1;
tline = fgetl(fid);
A{i} = tline;
while ischar(tline)
i = i+1;
tline = fgetl(fid);
A{i} = tline;
end
fclose(fid);

% Change cell A
A{19} = sprintf('R0 (Vout 0) resistor r=%d',P);

% Write cell A into txt
fid = fopen('input.scs', 'w');
for i = 1:numel(A)
if A{i+1} == -1
fprintf(fid,'%s', A{i});
break
else
fprintf(fid,'%s\n', A{i});
end
end


% Run spectre and compute function value
!spectre input.scs;
signal = cds_srr('input.raw','tran-tran','Vout');
F1 = signal.V(end) - 0.5;
F = abs(F1);

end
end

    I will be pleased to explain more about this approach for any one who is interested.

Sincerely Yours,

Milad

Milad,

The simulink flow is primarily intended for simulating a system simulation with a mixed-signal implementation. It's not been designed with optimization by Matlab in mind (we have our own optimizer for circuit optimization). Consequently, passing information other than normal signals was not part of the design brief and there are no plans to change this as far as I know.

The Simulink-AMS or Simulink-Spectre interface is great for when you want to model your encoding scheme (e.g. OFDM modulation etc) through a receiver and then decode the received OFDM and so on and look at BER and similar metrics. All those communication blocks in Simulink become very useful.

Regards,

Andrew.

Dear Andrew,

    Many thanks for your explanation. You mentioned something about your own "optimizer". May I know more about it and the methodology you use for any kind of circuit optimization problems?

Sincerely Yours,

Milad

Milad,

Please read the Analog Design Environment GXL documentation. You can also look at the Rapid Adoption Kits page on the support site, and look at the "Statistical Analysis" rapid adoption kit, which I believe (if my memory is correct) covers some aspects of circuit optimization. Otherwise contact customer support as we should have another workshop example that takes you through global and local optimization.

Regards,

Andrew