User`s guide

Control System Parts 6
-15
FTABLE
The FTABLE part is described by a table of frequency responses
in either the magnitude/phase domain (R_I= ) or complex
number domain (R_I=YES). The entire table is read in and
converted to magnitude in dB and phase in degrees.
Interpolation is performed between entries. Magnitude is
interpolated logarithmically; phase is interpolated linearly. For
frequencies outside the table’s range, 0 (zero) magnitude is
used. This characteristic can be used to impose an upper and
lower limit on the output.
The DELAY attribute increases the group delay of the
frequency table by the specified amount. The delay term is
particularly useful when a frequency table device generates a
non-causality warning message during a transient analysis. The
warning message issues a delay value that can be assigned to the
symbol’s DELAY attribute for subsequent runs, without
otherwise altering the table.
The output of the part depends on the analysis being done. For
DC and bias point, the output is the zero frequency magnitude
times the input voltage. For AC analysis, the input voltage is
linearized around the bias point (similar to EVALUE and
ROWn either an (input frequency, magnitude, phase)
triplet, or an (input frequency, real part,
imaginary part) triplet describing a complex
value; by default, up to five triplets are
allowed where n=1, 2, 3, 4, or 5
DELAY group delay increment; defaults to 0 if left
blank
R_I table type; if left blank, the frequency table is
interpreted in the (input frequency,
magnitude, phase) format; if defined with any
value (such as YES), the table is interpreted in
the (input frequency, real part, imaginary
part) format
MAGUNITS units for magnitude where the value can be
DB (decibels) or MAG (raw magnitude);
defaults to DB if left blank
PHASEUNITS units for phase where the value can be DEG
(degrees) or RAD (radians); defaults to DEG
if left blank
If more than five values are
required, the symbol can be
customized throu
g
h the symbol
editor. Insert additional row
variables into the template usin
g
the same form as the first five,
and add ROW
n attributes as
needed to the list of attributes.