Sonnet User's Guide - Sonnet Software

Sonnet User’s Guide
ing the dielectric layers (which includes the height of the box top), top and bottom
box metals, metal and dielectric brick materials, cell size and box size. This saves
the effort of having to enter these values in each of the subprojects.
Setting Up the Coarse Step Size Frequency Sweep
If you plan to use interpolation to obtain response data when analyzing the master
netlist project, you should input the coarse frequency sweep at which you wish to
analyze the geometry subprojects before subdividing the circuit. These frequencies
should cover the same frequency range as the analysis frequencies for the
whole circuit but use a coarser step size. The subprojects should be analyzed at the
same minimum and maximum frequency as the overall analysis and at enough
points in between to provide for reasonable interpolation of the response.
By inputting the coarse frequency sweep prior to subdivision, the master netlist
and geometry subprojects created by the subdivide command will all inherit the
analysis setup. After subdividing, you will need to enter the desired finer frequency
step size in the master netlist project before analyzing it. In addition, you will
need to turn off Hierarchy Sweep.
The figure below shows a Smith chart with a circuit analyzed at five frequency
points, next to the same circuit analyzed at only two points. As you can see, using
only two data points would result in more interpolating error than using five data
points. Whether or not two data points is acceptable depends upon the proximity
of points A and B. If A and B are very close, then two data points are sufficient.
If A and B are far away, then five or more data points should be used.
B
A
It is always a good idea to check the Smith chart for the response data of your subprojects
to ensure that you have chosen enough frequency points at which to calculate
data so that any interpolated data is reasonably accurate.
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