eldo_user

Working with S, Y, Z Parameters
Instantiating a Block Defined by S, Y, Z Parameters
solution is fixed. The decision about pole reduction is made from considering the solution
step (pole is too “fast”), or the duration of the simulation interval (pole is too “slow”).
Therefore, the set of actually used poles is defined “dynamically” from considering the
parameters of the .TRAN command. The generated list of poles/residues (*.pls) file remains
unaffected. Pole reduction does not considerably affect the solution accuracy. However, if
the precise simulation is needed, the option can be disabled by setting
POLE_REDUCTION=0.
• HIGH_PRECISION=val
Set to 1 to increase the fitting accuracy by enabling more poles than in regular mode (with
default value 0). This option can be useful for verification purposes, for example if a
“reference solution” is required. However, it is not recommended if the input data itself is
not very accurate. Also, since high-precision fitting produces more poles, it makes
simulation slower.
• MAXROW=val
Sets the limit (val/2) to the frequency points of the original dependence used in fitting. The
default value is 40000, corresponding to 20,000 points.
• MAXCOL=val
Sets the limit (val/2) to the maximal order of complexity for fitting in CPF. The default
value is 1500, corresponding to an order of complexity of 750. For very complicated (sharp,
irregular) dependencies it is sometimes reasonable to reduce the order of complexity,
especially if we have reasons not to entirely trust the input data at higher frequencies. As a
rule, reducing the order of complexity is a better strategy than reducing the number of points
to consider (MAXROW).
• IDX_F=val
Defines the index (integer number) VAL associated with the S parameter file (IDX_F=VAL
implies that the input parameter file is named sbVAL.par). Alternative way of defining the
input data file; see also the STRING: keyword.
• SINGLE_REFERENCE_NODE=val
Set to 1 to support a single reference node. When the number of pins of the FBLOCK model
is even, Eldo considers that each port has two pins. When the number of pins is odd, Eldo
considers the reference pin is the same for all ports (and it is the last pin). Specify
SINGLE_REFERENCE_NODE=1 to enable the FBLOCK model to consider the last pin as
the common reference pin for all ports if the number of ports is the number of pins−1.
• STRING:
Used to define the name of the touchstone file, CITIfile, or poles/residues file (.pls),
containing the input data. Path definition is allowed. Another way of defining the data file is
using the IDX_F parameter under the keyword PARAM: together with all the other
parameters, not under the STRING: keyword. If not specified, sbVAL.par is used by
default, where VAL is defined by IDX_F, or the number of ports otherwise.
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Eldo® User's Manual, 15.3