Sonnet User's Guide - Sonnet Software

Chapter 5 Ports
This type of co-calibrated port is illustrated below. The positive terminal is attached
to a polygon edge of a feedline and the negative terminal is attached to a
via to ground which is removed during de-embedding.
+
Via to Ground
Via to Ground
+
Box wall
port on
page 46.
When the Sonnet box is selected as the ground node connection, the analysis engine
automatically determines the most efficient direction the ground via extends
taking into consideration both the distance and the loss of the box top or bottom.
When using this type of ground, you must make sure that there is a clear path with
no metal on other levels interfering with the path to the box top and bottom.
In addition, either the box top or bottom must have loss less than 50 ohms/sq. For
example, you should not use “Free Space” for both your box top and bottom definition.
If the loss is too high on both the box top and bottom for a ground via from
the Component to be attached, the analysis engine will issue an error message.
Floating: When the ground node connection is defined as Floating, all co-calibrated
ports in the group are connected to a common ground but not to the Sonnet
box. Instead, the ground node is left unconnected to the rest of your circuit. You
should choose this option if the element model or measurement data that will be
connected to these ports does not have a ground reference, or does not have shunt
elements. Examples of this are:
• A series RL equivalent circuit
• S-Parameter data that was measured without any pads
This type of co-calibrated port is illustrated below. Sonnet automatically adds extra
metal which connects the co-calibrated ports in a calibration group. This extra
metal is defined as Generalized Local Ground (GLG) metal since it acts as a local
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