Analysis Box Options dialog box
The Analysis Box Options dialog box is opened when you click on the Options button in the Analysis Box section of the Cadence Virtuoso Interface main window. This dialog box allows you to control the size and properties of the analysis box. See below for details about the controls.
The entries in this section define the area of the box, and include Cell Size and Num. Cells. In the Cadence Virtuoso Interface, the initial size of the box is determined by the size of the Virtuoso Sonnet em View you are translating to Sonnet and may only be changed by the addition of margins. Therefore the Box size may not be directly edited, but you may change either the Cell Size or the Number of Cells. Changing one of the entries will cause the other factor to be updated. These three values are related in the following manner:
Num. Cells * Cell Size = Box Size
where Num. Cells must be an integer.
Cell Size: This entry row defines the size of a single cell of the box area and is identical to the entries shown in the main interface window. See "Cell Size" in the Analysis Box Section for a detailed explanation of the cell size.
Num. Cells: This entry row defines the number of cells in the box area. You enter an X dimension (width) and a Y dimension (height). If you wish to change the number of cells, click on the Num. Cells radio button to the left of the text entry boxes. The number of cells must be an integer number in both dimensions.
Note that the cell size is updated to the closest allowed cell size which allows for an integer number of cells to fit in the box area.
Top Metal Cover, Bottom Metal Cover: These drop lists allow you to select the metal type for the box top and box bottom. You can choose either a predefined metal type or user defined Sonnet material. You may not use a material that is defined using the thick metal model for a box top or bottom. For details on defining a new material and their parameters, see the Material Setup dialog box.
There are three predefined metal types available in Sonnet:
WG Load is useful for modeling infinite arrays. The top or bottom cover is terminated with a perfectly matched waveguide load. Note this is not the same as an open environment. To model an open environment select Free Space, which sets the impedance of the cover to 377 ohms/sq, the impedance of free space. Note that the sidewalls are always modeled as perfect conductors.
This section of the dialog box may be used to increase the box size in Sonnet and to set the reference plane lengths. Sonnet’s analysis engine has an automatic de-embedding capability. When invoked, the solver removes the port discontinuity and a desired length of transmission line. The reference planes instruct the solver as to the desired length of the transmission line to be removed. One reference plane length per box side may be specified.
Adding a margin moves the box wall out that distance from the bounding box for the Virtuoso Sonnet em View being translated. A feedline from the Virtuoso pin (Sonnet port) is added to the circuit and a reference plane is set for the length of the feedline if reference planes are selected for that port. You may see the box in the Layout window while you are changing the margin by clicking on the Show Box button.
The box size is based on the physical size of the imported circuit. A bounding box is placed around the circuit polygons and the size of the bounding box is used as the base size of the box. If you wish to expand the box to be bigger than the size of the circuit you may add margins to the box size. You may add a margin to any of the four box walls: top, bottom, left or right. The margins do not have to be equal for different box walls. The default settings work for a majority of circuits, but in some cases you may wish to change the box size.
% Circuit Size: Select this radio button if you wish to define the margin as a percentage of the circuit size. Enter the desired percentage in the Top, Bottom, Left and Right text entry boxes. For example, if your circuit is 50 microns by 50 microns and you enter 10, then the box size will be increased by 10% (5 microns) in the direction of the selected box wall. The default for this setting is 100% for each box wall.
Microns: Select this radio button if you wish to directly enter the desired length of margin. Enter the desired length in microns in the Top, Bottom, Left and Right text entry boxes. The default for this setting is the length of that dimension of the bounding box for the circuit. For example, if your bounding box is 200 X 250 microns, then "200" would be entered in the Left and Right text entry boxes and "250" in the Top and Bottom text entry boxes.
Estimate Memory: Clicking on this button has the same effect as the Estimate Memory Button on the main interface window.
Show Box: Clicking on this button, displays an outline of the analysis box in your layout. The outline appears in yellow. To remove the box outline from your Sonnet EM view, click on the Hide Box button.