Monte Carlo Specific Tolerance

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Modified by Admin on Sep 13, 2017

The Monte Carlo Specific Tolerance Dialog.

Summary

This dialog allows the designer to setup specific tolerances for components in Monte Carlo analysis.

Access

In Analysis Setup dialog, choose Monte Carlo Analysis, in Monte Carlo Analysis Setup grid area, click ... button in Specific Tolerances row.

Options/Controls

Each component can have two tolerances set: a Device tolerance and a Lot tolerance. Both device and lot tolerances are allowed, but only one is required. For a specific component, device and lot tolerances are calculated independently (using different random numbers) and then added together.

Designator - Choose the component that the specific tolerance is to apply to, from the drop-down list. Include a parameter in the Parameter field if the device requires it. Supported parameters include: the propagation delay of a digital component, the Beta forward of a transistor and the resistance of a potentiometer.
Parameter - Include a parameter if the device requires it. Supported parameters include; the propagation delay of a digital component, the Beta forward of a transistor, and the resistance of a potentiometer.
Tolerance - Set the Tolerance field to give the percentage tolerance for the component.
Tracking No - Assign a common tracking number to devices when you require the variation in their tolerance to be correlated.
Distribution - The Distribution field is used to specify the distribution type used for random number generation (Uniform, Gaussian or Worst Case).

If you give two devices the same Device Tracking Number and Device Distribution, then the same random number is used for both devices when the device values for a simulation run are calculated.

Combined device and lot tolerances are useful where values are not completely correlated, but are not completely independent either. An example would be two different resistor packs. Here, the lot tolerance can be large (that is, the variation from wafer to wafer), while the device tolerance (the variation from resistor to resistor in the same package), is small. In this case the device tolerance should not be ignored because it may limit the overall performance of a circuit.