eldo_user

Eldo Netlist Setup
Merging Instances in Parallel
• Subcircuit instances
The ASCII .chi output file lists the number of devices and subcircuit instances merged. For
example:
Number of X instances merged 3
Number of devices merged 5
To report all of the merged elements specify option CATMX_REPORT. In this case, the ASCII
.chi output file contains the instances that have been merged. For example:
X4 merged with X1
X3 merged with X1
X2 merged with X1
R6 merged with R1
R5 merged with R1
R4 merged with R1
R3 merged with R1
R2 merged with R1
The merging is done to speed-up simulations. However, this may also result in unexpected
warnings in the following situations:
• If an instance name is specified in a .PRINT/.PLOT/.EXTRACT, and if this instance is
merged with another, Eldo issues a warning that the instance is not found. For example,
with .PRINT dc ix(x2.1) Eldo issues a warning that instance x2 is not found.
• The output may take into account the M factor. For example, .PRINT IX(X1.1) will
return twice the number values obtained compared with if the instances had not been
merged. For MOS instances, if the M factor specification is not equal to 1 (default) the
merging of devices is not performed.
• If option MINRAVL is specified, and if there are resistors inside some X instances
which are merged, the working resistance of the device is R/M, where M is the number
of items in parallel. R/M can become < MINRVAL when R was > MINRVAL. This
should have limited impact on the results.
• When using high impedance (Hi-Z) checking commands, impedance is not computed on
the internal nodes of merged instances. Eldo issues a warning in this case to disable
merging instances in parallel so it can compute the impedance of those nodes.
To disable merging instances in parallel, specify option NOCATMX or invoke Eldo with the
-nocatmx argument.
Eldo® User's Manual, 15.3 159