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What's Good About PCB SI Adaptive Mesh Generation? 16.5 Has Many New Enhancements!

Comments(2)Filed under: PCB Signal and power integrity, PCB design, SPB, High-Density Interconnect, HDI, PDN, Allegro, field solver, SI, Signal Intregrity, PCB, SigXP UI, PCB SI, SI analysis and modeling, "PCB SI", "PCB PI", full wave, PCB PI, High Speed, PI, SPB16.5, Allegro 16.5, OrCAD PCB SI, Allegro PCB SI, signal integrity, full-wave, PDN Analysis, SI bus analysis, Grzenia, meshing, adaptive mesh generation

The 16.5 PCB SI product’s rectangular mesh scheme is used for shapes, cutouts, slots, anti-pads and voids within shapes. The mesh cell size you pre-specify is the maximum cell size ,and the system will automatically adjust/reduce the cell size if necessary. You can ignore the meshing for anti-pads and small shapes/voids through the Preferences settings.

Read on for more details …

Analyze Menu

All analysis functionality is available on the main PDN Analysis GUI:


In the mesh dialog, there is a brief description for meshing and all functions:



Selecting the Preferences button brings up the Preferences form:


The General tab sets many of the default values. The Simulation tab sets the frequency range and maximum number of points for frequency-domain analysis, duration time, and time step for time-domain analysis. The top section of the Field Solver tab contains the settings for mesh generation:


The Mesh settings are one area of settings where a tradeoff between accuracy and performance is set. The default settings are for a Regular mesh with all voids in shapes included in the mesh. If you select the Ignore option from the following drop-down list, then all anti-pads of vias/pins will be ignored during the meshing. If you select the Include option, then all anti-pads of vias/pins will be meshed exactly:


You can ignore small island shapes or small voids by specifying a value for Ignore all shapes/voids less than:


This value is a scale factor of the maximum mesh cell size you specified (fine, regular or coarse or custom size).
Start the mesh by selecting the Mesh button on the Power/Ground Plane Meshing form:


Once the meshing is started, you will see a progress dialog appear and then the PDN Audit Results:


Mesh Results

Depending on your layer settings or specific design configuration, you may not see any mesh displayed in your design:

To aid in reviewing any PDN results including mesh generation, it is recommended that you pin the Options and Visibility fold out window panes in the PCB SI canvas:


The Options panel displays the type of analysis run and allows you to cross probe to the canvas and select the layer to review. Use the Review pull-down in the Options panel to review a specific layer of interest in the design. Select the mesh in the canvas to see the net name appear in the Options panel:


Please share your experiences using this new 16.5 capability.

Jerry "GenPart" Grzenia


By DCX PCB on August 28, 2012

By jack on September 3, 2012
OMG great tutorial…very simple but outstanding Very helpful in designing very nice tut..

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