8 em simulation
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Introduction to EM SimulationIntroduction to EM SimulationIntroduction to EM SimulationIntroduction to EM Simulation
Microwave Office Training
2 EM Simulation
EM Simulation
EM simulation setup has changed in 7.5.
EM uses drawing layers.
Case 1: Draw and Simulate a Structure in the EMEnvironment.
Case 2: Using a Layout Created in the EM Environment innormal layout.
Case 3: Importing DXF and GDSII Layouts Into EM.
Case 4: Extracting layout from the Schematic Layout.
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3 EM Simulation
The EM Environment
Step 1: Open up the project 4Layer_PCB_Start.emp.
This is the EM Socket. Projects go in here.
To create a project - RC on EM Structures.
The various EMsimulators - we are
using EMSight.
4 EM Simulation
EM Enclosure Settings
The Enclosure menu controls many of the important features of EM:
X and Y box dimensions, and grid size.
Bulk material properties.
Dielectric Layer Setup.
The conducting line properties - layer, conductivity, and thickness.
EM Layer Mapping (Used when working with schematic layout andartwork cells.
Note: Later we will
be seeing theStackup Element for
extraction.
It is almost the same
as the Enclosure
(with some extra
features).
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5 EM Simulation
EM Enclosure Settings - 2
Sets the x and y dimensions of the enclosing box. The height (z) weset later.
Sets the grid in the x and y directions. You want the box size a wholenumber of cells.
Enclosure
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Grid Size Tips
Lines should be 3 to 5 cells wide.
Edge couplers might require more.
Box size - Dont have the wall too close to nearestmetal ... two substrate heights away is good.
Make sure gaps / spacing in filters is an integernumber of cells.
If possible - start on a simple problem you know theanswer to - simple bend, open line, 2 coupled lines,...
Gives you an idea how many cells to use.
Double your number of cells and see if your answerchanges a lot.
Note: 1000 unknowns - runs in 30 seconds/frequency.
Solution time grows as N3...10,000 unknowns - 30,000 seconds/frequency.
Number of Unknowns.
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EM Enclosure Settings - 3Material Definitions
Adding Dielectrics
Conductor Properties
Used for Surface Impedances
New in 7.5 - Preset values remember materials you added before.
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EM Enclosure Settings - 4
Dielectric Layers
Materials can be picked from
the list of Dielectrics.
Draw scaleused for 3D
visibility.
New in 7.5 - Place the mouse
on a layer to see its properties.
Can set the top and bottom Boundary Conditions.
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EM Enclosure Settings - 5
Materials
Sets the conducting lines properties:
The thickness of the line.
What its made of (from list of Conductors in Material Definitions).
Note: Etch Angle and Roughness are reserved for future use.
New in 7.5: Perfect Conductor will always exist -
made out of material definition - PerfectConductor.
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EM Enclosure Settings - 2
EM Layer Mapping
This controls how drawing layers are mapped to EM layers. Wellworry about it later.
New in 7.5: This mapping is in the Enclosure Options.
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11 EM Simulation
Drawing in the EM Environment
To draw in EM:
Select an EM Layer.
Select Material.
Select Conductor or Via.
Extent is how many
layers down the via
extends.
New in 7.5: The stackup display shows you
the layer you are on.
12 EM Simulation
Drawing in the EM Environment - 2
Step 2: Draw a line -60 mils wide - layer
3 to layer 4
connected by a via(50X60mils).
Use material - c - as
the conductor.
Draw Tools
New in 7.5: There isnot any separate
button for vias.
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Drawing in the EM Environment - 3
3D View
The 3D view shows the
structure to be simulated.
New in 7.5: Always check the
3D view - it will only showwhat is being included in the
simulation.
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Drawing in the EM Environment - 4
Adding Edge Ports
Step 3: Add an edge port to each of the lines.
Select the line.
Select the edge port icon, and click at the end of the line.
Double click the edge port and use the drag handles to
select the deembedding length.
EM StructureLayout
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15 EM Simulation
Ports
You can double click
on a port and changeits impedance. Also
can change how much
power goes into it.
Note: This only affects current and antenna pattern viewing. S
parameters are not changed.
There are 3 kinds of ports:
Edge Ports - Like networkanalyzer hooking up at edges
of structure.
Via Port - One port to top orbottom of box (ground). Like 1point probe.
Internal Port - Across gap -like 2 point probe.
Tip: Be careful! Where
is ground for an internal
port?
There are 3 Webinars in KB on
this - EM Simulation: A LookUnder the Hood: 1, 2, 3.
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Drawing in the EM Environment - 5
Properties of an EM Shape
RC on any shape- Properties.
You can change a shapes material and EM layer.
Note: The Mesh Options Tab controls how finely a shape is
meshed. You normally dont change this - unless you want tooverride default automesh settings.
You can see the shape properties in the Lower left corner of the UI.
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Drawing in the EM Environment - 6
Showing Only Active LayerNew in 7.5: There are various new viewing options for
understanding layers.
RC in the stackup display -
Hide Shapes on Non-active
Layers.
In this example - only layer 3conductors and vias will be
visible.
Tip: You can use the mouse wheel to go through the layers.
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EM Simulation Options
RC to set solver options.
RC on project to get individual project options.
Some global options under: Options > EM Options.
EM Options for an EM Structure
This tab is simulator specific.
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EM Simulation Options - 2
Frequency Control
Project frequencies can
be overridden locally.
You can set themeshing frequency if
you wish.
Tip: Often you wantfewer EM
frequencies
because of longsimulation times.
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EM Simulation Options - 3
Advanced Frequency Sweep
AFS - simulates over frequency band with (hopefully) fewer frequencies
and (hopefully) more accuracy than just set, discrete frequencies.
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EM Simulation Options - 4
AFS adds frequency points up to the maximum - until
convergence is reached.
You can specify a band besides the default if you want.
Note: When AFS is finished, the frequency points
displayed in graphing will be the original points in thefrequency tab... So - you might want to set at a high
number.
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EM and Normal Layout
Schematic Layout and Artwork Cells use Drawing layers that havealready been named.
The EM Mapping file is used to give drawing layers material
properties (conductivity and thickness) and layer position.
There are a number of scenarios where this is needed:
Importing Artwork cells to EM for simulation.
Using an EM layout in schematic layout.
Extracting a circuits schematic layout to EM layout.
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Using an EM Layout in SchematicLayout
When we created our EM project - what drawing layers did it use?
Remember - If you can see it, its a drawing layer!
Answer - it autogenerated these drawing layers.
Note: All autogenerated EM layers begin in +.
So long as we are only in EM - this is fine.
But - what happens if we use this layout in the schematic
layout?
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Using an EM Layout in SchematicLayout - 2
Step 4: Create a new schematic - EM_as_Sub-circuit.
- Add the EM Structure as a sub-circuit.
Schematic View
Layout View
It draws on the error layer.
The problem is the schematic layout has no idea where to put the auto-generated layers.
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Using an EM Layout in SchematicLayout - 3
The secret is to understand the EM mapping file. It lives in the LPF file.All layouts - schematic layout, artwork cells, EM projects ... have an
LPF file. All LPF files have an EM mapping file - it tells the materialsand line position in the stackup for each drawing layer.
EM Mapping file for
EM project - start.
These 3 layers have
material and EM layer
position. Note: Layer
number is top of
dielectric layer.
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Using an EM Layout in SchematicLayout - 4
Default LPF forproject.
The schematic layout uses the default project LPF, and
its EM Mapping.
This is why it doesnt know what to do with the autogenerated layers...
They arent even defined in the schematic layout LPF.
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Using an EM Layout in SchematicLayout - 5
To fix the problem - The EM projects LPF was generated from the project LPF - then the
autogenerated layers were added.
We fix the project LPF - so that any EM project we create will have
the right mapping.
Step 5: Modify 4LayerPCB.lpf.
Modified default LPF. Note: A commonmistake is to
misspell the
material name.
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Using an EM Layout in SchematicLayout - 6
Step 6: Update the dependent LPFs (i.e. the EM projects created).
RC on the LPF in Layer Setup -
and Update.
You can select the Dependent LPFs to update.
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Using an EM Layout in SchematicLayout - 7
Schematic Layout
The EM auto
generated layers
have disappeared.
They arent needed. For example, itknows if you want a conductor on em
layer 3, you are on drawing layer
met2.
Note: Any new EM projects will alsohave this mapping - as they are
generated from the default project LPF.
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Options for Viewing Layers
There are a variety of viewing options.
RC in the drawing layers pane.
Options for viewing:
Shapes on unmapped layers.
Shapes on mapped layers.
Shapes on missing layers.
Ive uncloaked all unmapped
layers. An X indicates unmapped.
Tip: The 3D EM view only showsmapped layers. Good way to see
what is really simulating.
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Multiple EM Mapping Files
You can have multiple EM Mapping Files. You can create these forthe project LPF, or for EM Mapping File for a given project.
Different EM
Mappings
Examples:
Switch between
lossy lines and
perfectconductors.
In MMIC - mightnot want to map
to EM all metallayers.
Different LPF files.
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Importing DXF and GDSII into EM
External World
GDSII Libraries
DXF Libraries
Artwork Cell Layout
EM Layout
Looks for Model
Layers by same
name - or
creates them.Step 7: Import mypad.dxf.
Method 1:
Copy and paste the drawing layers.
Select the shapes and change the
layers.
Method 2:
Change the EM Mapping file - so canrepeatedly use the mapping in the future.
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Method 1: Import and Change theLayers
Step 8: Copy the EM project - start. Rename the copy to Via_Sim.
- Delete the structures.
Tip: One way to make many EM
projects with same settings - is
to copy an empty EM project.
Step 9: Copy and paste the artwork cell - New_DXF_Cell
into the EM Project.
- You can use Ctrl - C, Ctrl - V.
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Method 1: Import and Change theLayers - 2
Its placed on the Error layer.
You can fix it by selecting the properties of each element ...
and moving it to the right drawing layer.
Step 10: Set the shapes on
TopMetal to met1... the
shape on Pad to EMLayer
2, Via.
Settings for TopMetal Settings for Pad
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Method 1: Import and Change theLayers - 3
To finish it up - you would change the box size, and extend the
line and add a port.
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Method 2: Update the EM Mapping inthe LPF File
Step 11: Create a
new EM Mapping -call it PadMap.
Step 12: Setup the mapping or Pad and TopMetal.
Note: We could have just modified the Default Mapping - but this
gives us practice with multiple EM Mappings.
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Method 2: Update the EM Mapping inthe LPF File - 2
Step 13: Copy the EM Project - start - rename it to Pad_with_Mapping.
- Delete the shapes.
Step 14: Update Dependent LPFs - select only+Pad_with_Mapping.
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Method 2: Update the EM Mapping inthe LPF File - 3
You have the EM Mappings from the LPF in the EM project.Select PadMap - and you can now import the shapes.
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EM Extraction
Extraction sends selected PCells and other shapes to the EM Socket.
Advantages
Drawing carried out by the PCells.
As schematic layout changes - can keep sending new layout to EM
simulator easily.
Ports, and deembedding lines are automatically included.
S parameter results are automatically brought back into the
schematic and re-simulated.
Disadvantages Almost too easy! Never see the EM layout.
Box can be too small, wrong layers, boundary conditions...
Can get off mesh.
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EM Extraction - 2
Step 15: Open up the project double_stub.emp.
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EM Extraction - 3
Make sure the layout is connected. Simulation Results.
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EM Extraction -4
To extract the circuit to EM we need two elements.
The Extraction Element
Elements > Simulation Control
Elements > Substrates
The Stackup Element
Controls
Size of enclosure and mesh
Simulator Type
What elements are extracted.
Controls
Layers, Materials, ...
Its essentially the same as Enclosure withextra feature of Line Type extractions.
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EM Extraction - 5
Step 16: Add the Extraction block to the schematic and configure it.
EM_Doc - The EM Project created.
Name - The extraction group name.
Extension - The box will be thismuch bigger than nearest
conductor.
Note: Put in .
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EM Extraction - 6
Step 17: Configure the Stackup block.
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EM Extraction - 7
Note: When you
change the mappingfile - you will get a
warning ... nextslide.
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EM Extraction - 8
Line Type Mapping - This can be used as an alternative to EM
mapping - when you setting up what EM Layer and Material for aLine Type to use.
Note: It is normally used with iNets.
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EM Extraction - 8
The project LPF - will be changed to the new EM Mapping file. Be
careful before you do this.
Tip: Make a new EM mapping file - before you do this - so you
dont overwrite the original.
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EM Extraction - 9
Step 18: Select all the elements.
- RC on properties - enable all of them for extraction under
Model Options.
Dont use quotes!
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EM Extraction - 10
Selecting the Extract block shows the elements are enabled
for extraction.
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EM Extraction - 11
Step 19: RC on the schematic icon and Add Extraction.
The EM project is created.
Tip: Its always agood idea to checkthings over the first
time you extract.Look at the 3D, etc.
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EM Extraction - 12
Step 20: Enable AFS for the EM Project.
Simulate - and look at the results in the graph. Note the Sparameters are automatically updated.
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EM Extraction - 13
Note: After simulating the EM:
I froze the traces: Ctrl - F.
Went to the schematic and disabled the Extraction Block.
Resimulated. There is a large difference in filter response.
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53 EM Simulation
Viewing the Mesh
The mesh is viewed in the 3D view as an annotation.
Note: It doesnt need to simulate to see the mesh.
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Viewing Currents
Currents can be viewed as a 3D annotation.Note: You cannot
view currents withAFS turned on.
I disabled
AFS, and
simulated at 1
point - 20
GHz.
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Viewing Currents - 2
You can animate it - cycles throughphase.
EM 3D Layout Toolbar.