User`s guide

6
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44 Analo
g
Behavioral Modelin
g
TMAX is not specified it is assigned a value, or if it is specified,
it may be reduced.
For low pass and band pass filters, TMAX is set to (0.5/FS),
where FS is the stop band cutoff in the case of a low pass filter,
or the upper stop band cutoff in the case of a band pass filter.
For high pass and band reject filters, there is no clear way to
apply the Nyquist criterion directly, so an additional factor of
two is thrown in as a safety margin. Thus, TMAX is set to (0.25/
FP), where FP is the pass band cutoff for the high pass case or
the upper pass band cutoff for the band reject case. It may be
necessary to set TMAX to something smaller if the filter input
has significant frequency content above these limits.
Frequenc
y
tables
For frequency response tables, the maximum frequency is twice
the highest value. It will be reduced to 10/(RELTOL⋅TSTOP) or
8192 times the frequency resolution if either value is smaller.
The frequency resolution for frequency response tables is taken
to be either the smallest frequency increment in the table or the
fastest rate of phase change, whichever is least. PSpice A/D then
checks to see if it can be loosened without inducing sampling
errors.