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Speed and Accuracy
Simulation of Large Circuits
Related Topics
Speed and Accuracy in Eldo
Global Tuning of the Accuracy—EPS
Simulation of Large Circuits
The Eldo circuit simulator is capable of handling very large circuits. To handle such circuits,
containing several hundreds of thousands of components, memory usage becomes an important
consideration.
Tip
For more information on memory requirements and dimensioning, please refer to the AMS
Installation Guide.
For the simulation of large circuits, the following suggestions may help:
• Explore the manual.
There are many options and features that can significantly improve speed, and help with
the simulation of large circuits. Some of them are extremely specific and relevant only
in the presence of specific elements. A good place to start is the Simulator and Control
Options chapter in the Eldo Reference Manual, which lists all available .OPTION
statements. Of particular importance are those listed in the Simulation Speed, Accuracy,
and Efficiency Options table.
• Use a workstation with sufficient RAM and SWAP.
As with any software, an attempt to run a simulation with real memory far lower than
that required to contain the circuit can result in a phenomena known as “thrashing.”
When this occurs, CPU time is almost totally taken up in swapping data in and out of
main memory, with little or no useful computation being made. Any tool that monitors
process activity will report CPU usage, real memory usage, and swap usage. When
running large simulations, it is highly recommended to use of these tools to monitor the
simulation processes.
• Use the 64-bit version of Eldo.
If more than 2 GB of real memory is needed, consider using the 64-bit version of Eldo.
See “Running Eldo in 32-bit and 64-bit Modes” on page 42.
• Specify node number via MAXNODES and MAXTRAN options.
If you have an idea of the number of nodes and components (grounded capacitors not
included) your circuit has, it is wise to specify these options:
.OPTION MAXNODES=VALUE MAXTRAN=VALUE
1256
Eldo® User's Manual, 15.3