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Monte-Carlo
This is only available in SUMO-EXPERT .
The Monte-Carlo system of testing whether a circuit is OK when the components are varied within their tolerances. It is called Monte-Carlo after the famous Casino in Monaco, due to its use of chance. The SUMO system uses a time-based seeding of the random-number generator to ensure a truly random set each time.
Both sweeping and Monte-Carlo use the same simulation-setup menu. For each pass of either type, a circuit netlist is output that contains the component values for that pass, and the simulation details. The sweep will sweep the whole simulation, so if AC and TR are both specified, both will be swept.
Monte-Carlo simulations
The Monte-Carlo option should be selected in the sweeper menu, and the number of passes-1 should be set as the number of slices. This means if you want 10 passes you select 9 slices.
The Monte-Carlo requires at least one component to be set with a tolerance greater than zero. At netlist time the random variance is computed and the circuits are written out. The variance is linked to the system clock and randomly seeded each time.
Components tolerances can optionally be shown on the circuit diagram.
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The OPTIONS menu controls this with TOLS.
Press ALT-F for the FILE menu and click-on OPTIONS .
Simulation and viewing
Simulation is a two stage process. First as many netlists as there are passes are written out, under the filename SWP_<pass>.CIR. Then a .SWP file is constructed, containing a record of all the relevant component values..
Once the simulations are running, do not interrupt them as the consequences may not be predictable. If a simulation error occurs (usually as a result of a transient simulation not converging or values exceeding legal bounds) the simulation should stop and the output file is displayed, which should allow the fault to be identified.
After every simulation, the results of that pass are concatenated onto the results file. Sweeps and Monte-Carlo runs are all run in batch mode . This is for speed and simplicity. The data is then read into the viewer after all passes are complete.
After simulation, the viewer recognises the traces as repeats and displays them correctly. Each trace has the number of the simulation run associated with it. For instance, a trace called out now becomes out:0, out:1 ... out:n in the Create menu and for cursor values.
Clicking-on SWP in the viewer menu puts up a list of all component values for all sweeps.
By using the cursors and the list, the circumstances that produced that particular trace can be identified.
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