Analysis Box

Sonnet's analysis engine, em, analyzes planar structures inside a six-sided metal shielding box; therefore, the box needs to be specified. Port connections are usually made at the box sidewalls. The substrate is on the metal bottom of the box and represents the ground plane. Above the substrate are stacked the dielectric layers and metal levels. The side walls of the box are modeled as lossless metal. The top and bottom of the box may be assigned any metal type defined in the geometry project. This section of the main interface window controls the box size.

Cell Size: This entry row defines the size of a single cell of the box area. The Sonnet electromagnetic analysis starts by automatically subdividing your circuit into small rectangular subsections. The analysis engine uses variable size subsections. Small subsections are used where needed and larger subsections are used where the analysis does not need small subsections.

A Sonnet “cell” is the basic building block of all subsections, and each subsection is “built” from one or more cells. Thus the “dimensions” of a cell determine the minimum subsection size. You enter an X dimension (width) and a Y dimension (height). Note that the X and Y dimension can be different values and are not required to be integers.

Selecting cell size is important. The analysis engine automatically subsections the circuit based on the cell size. Small cells result in slower but more accurate analyses. For a detailed discussion of subsectioning, see Chapter 2 "Subsectioning" in the Sonnet User’s Guide.

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.

Options: Click on this button to open the Analysis Box Options dialog box which allows you to control the cell size and additional options for the analysis box.