Running the worst case Monte-Carlo Run ( in ADE-XL)

You can do this with Create Statistical Corner. On the Detail view, go to the points that you want to re-run, and use the Right Mouse Button menu over an output for that point and pick Create Statistical Corner:

This will add a new entry into your Corners. You can do the same again for the other point. Alternatively you can use a similar right mouse button  menu over an output in the yield view to pick the worst point, or a percentile point (e.g. the 95th percentile).

Then switch to Single Run Sweeps and Corners and run the simulation and it will just run those monte carlo points.

Now, one thing to be aware of is that this just runs a monte carlo running those individual points in the sequence by default. If you are using mismatch or all (i.e. process+mismatch) then the results will be consistent unless you change the topology of the circuit (parameter value changes are OK, but adding or subtracting instances will cause it to be different). That's because the mismatch parameters are computed in the simulator by rolling the dice for each instance - if the sequence of instances is different (i.e. there are more or less), then the point in the distribution you'll get will be different too. For process it's OK, because the dice is rolled to same number of times regardless of changes in the circuit.

To solve this, a new option was added in IC616 ISR6 (so the one before you're using). You can set this .cdsenv variable:

adexl.monte createStatisticalCornerType cyclic "sequence"

where the value can be set to "sequence", "prompt", "values" or "promptValues". You can also set this using SKILL in your .cdsinit :

envSetVal("adexl.monte" "createStatisticalCornerType" 'cyclic "promptValues")

The meanings are that sequence is where it just picks the point in the sequence of runs (i.e. the default behaviour), and values will cause it to save the mismatch and process parameters and re-use those (for any instance that is still in the design). If there's a "prompt" in the name it will ask you to confirm that choice when creating a statistical corner.

Note that for the "values" mode to work, you have to enable the Save Process Data and Save Mismatch Data on the Monte Carlo options form. This isn't done by default because there is a small (usually it's small, anyway) performance penalty to pay for doing that.

Regards,

Andrew.

You can do this with Create Statistical Corner. On the Detail view, go to the points that you want to re-run, and use the Right Mouse Button menu over an output for that point and pick Create Statistical Corner:

This will add a new entry into your Corners. You can do the same again for the other point. Alternatively you can use a similar right mouse button  menu over an output in the yield view to pick the worst point, or a percentile point (e.g. the 95th percentile).

Then switch to Single Run Sweeps and Corners and run the simulation and it will just run those monte carlo points.

Now, one thing to be aware of is that this just runs a monte carlo running those individual points in the sequence by default. If you are using mismatch or all (i.e. process+mismatch) then the results will be consistent unless you change the topology of the circuit (parameter value changes are OK, but adding or subtracting instances will cause it to be different). That's because the mismatch parameters are computed in the simulator by rolling the dice for each instance - if the sequence of instances is different (i.e. there are more or less), then the point in the distribution you'll get will be different too. For process it's OK, because the dice is rolled to same number of times regardless of changes in the circuit.

To solve this, a new option was added in IC616 ISR6 (so the one before you're using). You can set this .cdsenv variable:

adexl.monte createStatisticalCornerType cyclic "sequence"

where the value can be set to "sequence", "prompt", "values" or "promptValues". You can also set this using SKILL in your .cdsinit :

envSetVal("adexl.monte" "createStatisticalCornerType" 'cyclic "promptValues")

The meanings are that sequence is where it just picks the point in the sequence of runs (i.e. the default behaviour), and values will cause it to save the mismatch and process parameters and re-use those (for any instance that is still in the design). If there's a "prompt" in the name it will ask you to confirm that choice when creating a statistical corner.

Note that for the "values" mode to work, you have to enable the Save Process Data and Save Mismatch Data on the Monte Carlo options form. This isn't done by default because there is a small (usually it's small, anyway) performance penalty to pay for doing that.

Regards,

Andrew.