eldo_user

Monte Carlo Analysis
Specifying Statistical Variations
Statistical Configuration on Devices and Subcircuits
The device model argument, STATISTICAL=0|1, can be specified on X instances, device
declarations, or on .SUBCKT definitions, to specify whether any statistical variation due to .MC
can be applied to the specified entities.
If STATISTICAL is 0, the selected devices will keep their nominal values. If STATISTICAL is
1, the selected devices have statistical variation applied. The global default value can be
specified using the option STATISTICAL= 0|1. Default is 1. See the Statistical Configuration
Usage Example.
Note
When a Monte Carlo analysis is specified, merging devices or subcircuits in parallel (with
or without device multiplier M=val specified) is disabled.
Example of Process Variations on a Capacitor Model
The following example demonstrates the statements for a subcircuit to model a simple capacitor
device, and the effects of process variations upon this device. Typically, process experts create
libraries of subcircuits containing much more complex equations and interactions representing
the process effect. Here we have modeled the fact that large geometry devices tend to exhibit
better matching characteristics than small geometry devices.
In the subcircuit CAPA, a capacitor is connected across the two ports PLUS and MINUS. The
value of the capacitor is a function of the subcircuit parameters and the process parameters. The
subcircuit input parameters include the default values of the capacitor area CAREA and
perimeter CPERI (assuming a rectangular shape).
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Eldo® User's Manual, 15.3