Getting Started with HFSS 3D Layout: Low Pass Filter

Getting Started with HFSS 3D Layout: Low Pass Filter Release 2020 R1 January 2020
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Conventions Used in this Guide
Please take amoment to review how instructions and other useful information are presented in this guide.
l Procedures are presented as numbered lists. A single bullet indicates that the procedure has only one step.
l Bold type is used for the following: o Keyboard entries that should be typed in their entirety exactly as shown. For example, “copy file1” means the word copymust be typed, then a spacemust be typed, and then file1must be typed.
o On-screen prompts andmessages, names of options and text boxes, andmenu commands. Menu commands are often separated by carats. For example, “click HFSS>Excitations>Assign>Wave Port.”
o Labeled keys on the computer keyboard. For example, “PressEnter” means to press the key labeledEnter.
l Italic type is used for the following: o Emphasis. o The titles of publications. o Keyboard entries when a name or a variablemust be typed in place of the words in ital- ics. For example, “copy file name” the word copymust be typed, then a spacemust be typed, and then name of the file must be typed.
l The plus sign (+) is used between keyboard keys to indicate that you should press the keys at the same time. For example, “Press Shift+F1” means to press the Shift key and the F1 key at the same time.
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"On theDraw ribbon tab, click theBox primitive" means you can click theBox icon on the Draw tab and execute theBox command to draw a box.
l Themenu bar (located above the ribbon) is a group of themain commands of an application arranged by category such File, Edit, View, Project, etc. An example of a typical user interaction is as follows:
"On the Filemenu, click theOpen Examples command"means you can click the Filemenu and then clickOpen Examples to launch the dialog box.
l Another alternative is to use the short-cut menu that appears when you click the right-mouse button. An example of a typical user interaction is as follows:
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Getting Started with HFSS 3D Layout: Low Pass Filter
“Right-click and selectAssign Excitation> Wave Port” meanswhen you click the right- mouse button with an object face selected, you can execute the excitation commands from the short-cut menu (and the corresponding sub-menus).
Getting Help: ANSYS Technical Support
For information about ANSYS Technical Support, go to the ANSYS corporate Support website, https://www.ansys.com/Support. You can also contact your ANSYS account manager in order to obtain this information.
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Help Menu
To access help from themenu bar, clickHelp and select from themenu:
l HFSS Contents - click here to open the contents of the help. l HFSS Search - click here to open the search function of the online help.
Context-Sensitive Help
To access help from the user interface, do one of the following:
l To open a help topic about a specificmenu command, pressShift+F1, and then click the command or toolbar icon.
l To open a help topic about a specific dialog box, open the dialog box, and then pressF1.
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1 - Introduction 1-1
HFSS 3D Layout in ANSYS Electronics Desktop 1-1
Set Up an HFSS 3D Layout Design 1-3
2 - Create the Model 2-1
Insert Layers 2-1
Draw theModel 2-6
Set Up a Planar EMAnalysis 3-1
Set Up Frequency Sweeps 3-3
Explore Disabling Sweeps and Setups 3-6
View theMesh 3-8
View SMatrix Data 4-1
Plot Return Loss 4-3
Revise p2 Excitation and Animate Current Results 4-6
Frequency Animated Far Field Plot 4-13
Contents-1
Contents-2
1 - Introduction This chapter contains the following topics:
l Sample Project – Low Pass Filter l HFSS 3D Layout in ANSYS Electronics Desktop l Set up an HFSS 3D Layout Design
Sample Project – Low Pass Filter The figure below is a low pass filter that you will create as an HFSS 3D Layout design and analyze as a planar EM solution. Themodel consists of three layers, one signal layer, a dielectric layer, and a ground layer. You will define the layers, assign a custommaterial to the dielectric, draw the model, define the ports, and set up the solution.
After solving themodel, you will review the S Matrix results and plot the return loss and a Smith chart. You will also create a current density overlay, a far field display, and animate both of these results.
Figure 1-1: Low Pass Filter Model
HFSS 3D Layout in ANSYS Electronics Desktop HFSS 3D Layout offers several design simulators for HFSS, Planar EM, SIwave, EMI, and Nexxim.Within the scope of this guide, we will discuss thePlanarEMSolution Setup only.
Introduction 1-1
Figure 1-2: ANSYS Electronics Desktop – Analysis Setups for HFSS 3D Layout Designs
EMDesign simulators are the ideal tools for projects that involve full-wave or radiative effects for multilayered structures. For example, you can draw the physical layout of a patch antenna or amil- limeter-wave integrated circuit and then simulate the electromagnetic properties to display the following:
l Radiated electric fields l Basic electromagnetic field quantities l Characteristic port impedances and propagation constants l Basic far-field parameters for electromagnetic fields and antennas l GeneralizedS-parameters, andS-parameters renormalized to specific port impedances
For more information see the HFSS 3D Layout Simulator in themain help.
Introduction 1-2
The following sectionswill guide you through the physical design and EManalysis of a low-pass filter. As you work through this sequence of HFSS 3D Layout topics, you will learn the following:
l How to start ANSYS Electronics Desktop and explore the HFSS 3D Layout tools l How to use the HFSS 3D Layout ribbon, menubar, and shortcut menu l Terms and concepts essential to the simulation of an HFSS 3D Layout design l How to add a custom-defined dielectricmaterial to a design l How to create a report to display simulation results
Set Up an HFSS 3D Layout Design Before inserting an HFSS 3D Layout Design into your project, ensure that the ANSYS Electronics Desktop options are set appropriately for this exercise.
Launch ANSYS Electronics Desktop (EDT):
1. Launch EDT using the desktop shortcut ( ) or theWindowsStart menu.
There should be an empty project at the top of the Project Manager. However, if you already had EDT open and closed a previousmodel, you will have to create a new project (by completing optional step 2).
2. Optionally (if needed), on theDesktop ribbon tab, click New to create a new project. 3. Right-clickProjectx at the top of the Project manager and selectRename. Then, type
LowPassFilter as the new name and pressEnter.
Verify EDT General Options:
4. On theDesktop ribbon tab, click General Options. 5. In the tree on the left side of theOptions dialog box, expand theGeneral group and select
theDefault Options subgroup. 6. Ensure thatmm is selected from the Length drop-downmenu to usemillimeters as the
default length unit. 7. From theOptions tree, select the Layout Editor> Snapping subgroup. 8. Click Snapping tab, deselectSnap to grid, and ensure that your selected optionsmatch the
following settings:
Introduction 1-3
Figure 1-3: Layout Editor Snapping Options
9. From theOptions tree, select the Layout Editor> Display subgroup. 10. In theGrid panel, enter 10 mm forMajor and 1 mm forMinor, making sure that the unit
used for each ismillimeter (mm), the default setting.
Introduction 1-4
Figure 1-4: Layout Editor Display Options
11. ClickOK to close theOptions dialog box.
Insert an HFSS 3D Layout Design into Your Project:
12. On theDesktop ribbon tab, choose HFSS 3D Layout from the HFSS drop-down menu.
Alternatively, you can insert an HFSS 3D Layout using either of the following two options:
l Using themenu bar, clickProject> Insert HFSS 3D Layout Design. l Right-click the project name at the top of the Project Manager and choose Insert> Insert HFSS 3D Lay-out Design from the shortcut menu.
Introduction 1-5
13. If theChoose Technology dialog box appears, clickNone.
Figure 1-5: Choose Technology Dialog Box
The Layout Editorwindow appears.
l All EM designsmust define a process topology (also called a stackup). l Layout technology files provide a quick way to store frequently used process topo- logies. For example, an engineer who frequently uses a specific substrate can pre- specify the correct materials and stackupswith a single click.
l In this example, you will not use a layout technology file but will define the topology or stackupmanually.
14. Hide theMessageManager andProgresswindows if either is currently displayed. l On theViewmenu, you can deselect the check-boxes forMessage Manager and Progress.
l Alternatively, you can clickHide Messages andHide Progress along the bottom of the programwindow.
Introduction 1-6
2 - Create the Model The low pass filter model consists of a ground layer, a dielectric layer, and a signal layer. You will only draw objects on the signal layer, which you will name t1. In this section, you will define the stackup layers (topology) of themodel, draw the geometry of the filter, and assign the excitation ports.
This chapter contains the following topics:
l Insert Layers l Draw theModel Geometry l Assign the Ports
Insert Layers 1. Access theEdit Layers dialog box by doing either of the following:
l On the Layout ribbon tab, click Layout dialog. l From themenu bar, select Layout> Layers.
2. Under Stackup, in theEdit Layers dialog box, deselect the Laminate mode option. 3. Under Layer, click Insert below to begin inserting an infinite ground layer, Then, in theAdd
Stackup Layer dialog box, do the following:
Note:
When adding the first layer to the table, the actions of Insert above and Insert below are identical.
a. Enter g1 in theName text box. b. Choose signal from the Type drop-downmenu.
Figure 2-1: Inserting Ground Layer (g1)
c. ClickOK to add the layer.
Notice that thematerial copper is automatically assigned to signal layers.
Create theModel 2-1
4. Tomake theNegative column visible, right-click any one of the column header at the top of the layer table (such asMaterial, Type, orName) and select theNegative option, which is off by default:
Figure 2-2: Showing the Negative Column
5. Set the new g1 layer to be negative by selecting the check-box in theNegative column.
Note:
Activating this option tells the program that this is a ground plane layer. Any object you draw on a negative layer becomes a cutout in the ground layer (conductor removed). However, you will not be drawing any objects on the g1 layer for this model.
6. Deselect theRough option for this layer if it is currently selected.
Note:
If theRough option is selected, the surface roughness of the conductors is taken into account when approximating the impedance of the signal traces. However, surface roughness is ignored for ground layers. Deselecting this option prevents a warning to that effect from being encountered when validating themodel and solution setup.
Create theModel 2-2
7. Insert and define a dielectric layer as follows: a. Right-click the g1 layer and select Insert dielectric above from the short-cut menu.
Figure 2-3: Inserting the Dielectric Layer above Layer g1
b. In the new dielectric row that appears in the layers table, click theName text box and change the name to d1.
c. In the Thickness text box, specify 1.6mm.
Notice that thematerial FR4_epoxy, which is a common printed circuit boardmaterial, is automatically assigned to dielectric layers. In the next step, you will change this specification to a user-definedmaterial.
8. SelectEdit from theMaterials drop-downmenu in the d1 row.
Figure 2-4: Edit Material Command
In theSelect Definition dialog box that appears, do the following:
a. ClickAdd Material.
TheEdit Materials dialog box appears.
b. In theMaterial Name text box, entermy_d1. c. In theRelative Permittivity text box, enter 2.2.
Create theModel 2-3
d. Leave all other settings unchanged and clickOK to close theEdit Material dialog box. e. ClickOK to close theSelect Definition dialog box.
9. Insert a trace (signal) layer as follows: a. Right-click the dielectric (d1) layer and choose Insert signal above. b. In theName column of the new signal row, type t1. c. Select theRough option for this layer.
10. Ensure that theSolver option is deselected for all layers. You will not be overriding any of the default solver options.
11. ChooseSelect all from the drop-downmenu in the Layer section at the bottom-left corner of theEdit Layers dialog box to simultaneously select all three rows in the table.
Note:
Even if Select all is already showing in this drop-downmenu, choose it again to actually select all the layers.
12. Ensure that the second checkbox in theAttributes section of the dialog box is selected to ensure that all objects will be shaded, as opposed to a wire frame view (outline only):
Figure 2-5: Enable Shading for Drawn Objects
Create theModel 2-4
13. Verify that theEdit Layers dialog boxmatches the following figure:
Figure 2-6: Edit Layers Dialog Box
Note:
If you did not create the stackup in the correct order, rearrange the layers by clicking and dragging the selection handles in the leftmost column. Drag layer t1 to the top of the list, d1 to themiddle, and g1 to the bottom.
14. ClickApply and Close to apply the layer definitions and close theEdit Layers dialog box.
Create theModel 2-5
Draw the Model 1. On the Layout ribbon tab, select t1 from theActive Layer drop-downmenu:
Figure 2-7: Setting t1 as the Active Layer
2. Draw a rectangle: a. Do either of the following:
l On the Layout ribbon tab, click Draw rectangle. l Using themenu bar, clickDraw> Primitive> Rectangle.
b. Then in the Layoutwindow, click, move themouse, and click again to draw a rectangle of any location and size.
c. In the dockedPropertieswindow, ensure that 2Pt Description is selected, type 0,0 for thePt A value, type 20, 4.6 for thePt B value, and pressEnter.
Alternative Method of creating the rectangle (using the coordinate text boxes to specify the precise location and size of the rectangle while drawing it):
a. After initiating theDraw rectangle command, double-click in theX coordinate text box on theStatus Bar (located at the bottom of the ANSYS Electronics Desktop screen) and enter 0.
b. PressTab to move to theY coordinate text box, enter 0 here too, and pressEnter.
Note:
The Tab key switches between text boxes, while pressingEnter commits the data to the design. Also note that the first corner of the rectangle has been placed at the center of the grid per the 0, 0 values for theX andY coordinates.
Create theModel 2-6
Figure 2-8: Coordinates of First Corner of Rectangle
c. Complete the rectangle by entering the values of 20 forDelta X and 4.6 forDelta Y. Then, pressEnter.
Warning:
Be careful not to move themouse while inputting values in the coordinate text boxes, or the valueswill revert to the cursor location.
3. Fit the drawing to the Layoutwindow by doing one of the following: l PressCtrl+D.
l On the Layout ribbon tab, click Fit All. l Using themenu bar, clickView> Fit Drawing.
4. On the Layout ribbon tab, click Draw rectangle, then define the second rectangle as follows:
a. Click the lower-right corner of the first rectangle to snap the first corner of the second rectangle to that point. The cursor changes to a square shape when the snap point is found.
b. Double-click theDelta X text box and type 2.1. c. Tab to theDelta Y text box, type -10.5, and pressEnter.
5. On the Layout ribbon tab, click Draw rectangle, then define the third rectangle as follows:
a. In the coordinate text boxes, type 21.05 for X, 0 for Y, and pressEnter. b. In the coordinate text boxes, type 21.7 forDelta X, 0.7 forDelta Y, and pressEnter.
6. On the Layout ribbon tab, select Zoom Area from the Zoom drop-downmenu. Then, click and drag themouse to define a zoom area that tightly encloses only the right edge of the first rectangle, the top edge of the second one, and the left edge of the third one. The display should resemble the following figure:
Create theModel 2-7
Figure 2-9: Zooming into Polygon Area
7. On the Layout ribbon tab, click Draw polygon, then define the polygon as follows: a. Click the upper-right corner of the first rectangle. If you let themouse hover briefly
over the target point, the cursor becomes a square and jumps to the snap point. (The coordinates in the status bar should display 20.0, 4.6.)
b. Click the upper-left corner of the third rectangle (when the displayed coordinates are 21.05, 0.7).
c. Click the lower-left corner of the third rectangle (when the displayed coordinates are 21.05, 0.0). Note that the cursor may become a triangle in this case, since the snapping point corresponds to themidpoint of the second rectangle's top edge aswell as the end point of two of the third rectangle's edges.
d. Double-click the lower-right corner of the first rectangle ((when the displayed coordinates are 20.0, 0.0).
8. PressCtrl+D to fit the drawing within the Layoutwindow and click in the background area to clear the current selection.
At this point, your layout should look similar to the following figure:
Create theModel 2-8
Figure 2-10: Partially Completed Model Layout
9. Copy and paste a duplicate of all objects except for the third rectangle drawn, as follows: a. PressCtrl+A to select all objects. b. While holding downCtrl, click the third rectangle drawn to deselect it. The first and
second rectangle and the polygon should now be selected. c. PressCtrl+C to copy the selected objects to theWindows clipboard. d. PressCtrl+V to paste a duplicate set of objects into the Layout window. The location
of the pasted objects will move as youmove themouse, but do not click yet. e. Click a point within the Layout window to drop the objects anywhere that theywon't
overlap the original objects, but keep them selected afterward:
Figure 2-11: Copy & Paste Operation
Create theModel 2-9
10. On the Layout ribbon tab, click Flip> About Y (or, using themenu bar, clickDraw> Flip Horizontal).
11. Click on one of the selected objects and drag them so that the bottom left corner of the second polygon snaps to the bottom right corner of the third rectangle:
Figure 2-12: Positioning the Mirrored Objects
The result is a set of objects that are symmetrical about the vertical centerline of the assembly.
12. Clear the current selection and pressCtrl+D to fit themodel within the Layout window. The model should look like the following figure:
Figure 2-13: Model with Mirrored Objects Properly Positioned
13. On the Layout ribbon tab, click Draw rectangle, then define the final rectangle as follows:
a. In the coordinate text boxes, enter 29.3 for X, 0 for Y, and pressEnter. b. In the coordinate text boxes, enter 5.3 forDelta X, -10.5 forDelta Y, and pressEnter.
14. PressCtrl+A to select all objects in themodel.
Create theModel 2-10
15. On the Layout ribbon tab, click Unite.
The rectangles and polygons are united into a single object, and your layout should look similar to the following figure:
Figure 2-14: United Model Geometry
Note:
It is not mandatory to unite the individual shapes.Where they exactlymeet each other, the solver will treat them as a contiguous object. However, uniting them pro- duces a simpler model and eliminates the possibility of accidentally dragging one shape out of its proper position.
16. Click the united object to select it. Then, in the dockedPropertieswindow, change theName to Filter and pressEnter.
17. Click Save, which is located on all ribbon tabs.
Assign the Ports 1. CreatePort1:
a. PressE to begin theSelect Edgesmode.
l Alternatively, on the Layout ribbon, choose Select Edges from the selec- tionmode drop-downmenu (immediately below the Layers dialog command):
Figure 2-15: Choosing Selection Mode Via the Layout Ribbon Tab
l Or, from themenu bar, clickEdit> Select Edges. b. Click the left edge of the first (leftmost) rectangle to select it.
Figure 2-16: Selecting Edge for Port 1
c. On the Layout ribbon tab, click Create edge port.
Note that Port1 appears in the layout editor and is also listed in the Project Manager under Excitations.
Alternativemethods of adding a port. After selecting the edge:
l In the Project Manager, right-clickExcitations and chooseAdd Port. l Using themenu bar, clickDraw> Port> Create. l Or, right-click in the Layout window and choosePort> Create from the shortcut menu.
2. CreatePort 2: a. Click the right edge of the rightmost rectangle to select it.
Figure 2-17: Selecting Edge for Port 2
b. On the Layout ribbon tab, click Create edge port. 3. RenamePort 1:
a. In the Project Manager, under Excitations, right-clickPort1 and chooseRename. b. Type p1 and pressEnter.
4. RenamePort 2 (this time you will use an alternativemethod): a. In the Project Manager, under Excitations, clickPort2 to select it. b. In the dockedPropertieswindow, change thePort value (row 1, column 2) to p2 and
pressEnter.
3 - Set Up Solution and Analyze This chapter contains the following topics:
l Set Up a Planar EMAnalysis l Set Up Frequency Sweeps l Explore Disabling Sweeps and Setups l View theMesh l Explore DynamicMesh Updates l Run the Analysis
Set Up a Planar EM Analysis Each set of solution parameters to be solved by ANSYS Electronics Desktop is listed as a setup underAnalysis in the Project Manager. To add a new solution setup to this project using basic, ini- tial meshing tools, do the following:
1. On theSimulation ribbon tab, click PlanarEM (Add Planar EMSolution Setup).
Alternatively, complete this action in one of the following two ways:
l Right-clickAnalysis in the Project Manager and clickAdd Planar EM Solution Setupfrom the shortcut menu.
l Using themenu bar, selectHFSS 3D Layout> Solution Setup> Add Planar EM Solution Setup.
2. When thePlanarEMSetup dialog box appears, select Fixed Mesh, underMesh Selection in theGeneral tab.
Set Up Solution and Analyze 3-1
3. Enter 5GHz in theSolution Frequency text box.
Figure 3-1: PlanarEM Setup Dialog Box
4. ClickOK to accept the setup.
The Planar EMSetup dialog box closes and theEdit Frequency Sweep dialog box appears. You will define the frequency sweep in the next topic.
Note:
For more information on setting up an HFSS simulation, seeAdd HFSS Solution Setup in the product Help.
Set Up Frequency Sweeps To set up sweeps, you can choose to add either an interpolating sweep or a discrete sweep. You will define both types of sweeps. The procedural steps for setting up each sweep type are described below:
Add an Interpolating Sweep:
1. An interpolating sweep can be added in any of the following ways: l The sweep appears automatically after you create a solution setup. l Select the analysis setup in the Project Manager (in this case,PlanarEMSetup 1).
Then, on theSimulation ribbon tab, click Sweep (Set Up Frequency Sweeps). l Select the analysis setup in the Project Manager. Then, using themenu bar, click HFSS 3D Layout> Solution Setup> Add Frequency Sweep.
l In the Project Manager, expand theAnalysis folder, right-clickPlanar EM Setup 1, and clickAdd Frequency Sweep from the shortcut menu.
Any one of these actions opens theEdit Frequency Sweep dialog box associated with a Planar EM solution setup.
In the case of this exercise, theEdit Frequency Sweep dialog box should already be open as a result of completing the addition of a Planar EM solution setup in the previous topic.
2. Select Interpolating from theSweep Type drop-downmenu. 3. Select Linear Count from theDistribution pull-downmenu. 4. Enter the following sweep parameters:
l Start = 1.5 GHz l Stop = 5GHz l Points = 201.
TheEdit Frequency Sweep dialog box should now look like the following figure:
Figure 3-2: Edit Frequency Sweep Dialog Box – Interpolating Sweep
5. ClickPreview to display theSweep Pointswindow:
Figure 3-3: Sweep PointsWindow – Interpolating Sweep
6. Close theSweep Pointswindow. 7. ClickOK to add the interpolating sweep and close theEdit Frequency Sweep dialog box.
Add a Discrete sweep:
8. In the Project Manager (under Analysis), right-clickPlanar EM Setup 1, and clickAdd Fre- quency Sweep
9. ChooseDiscretefrom theSweep Type drop-downmenu. 10. Select Linear Count in the pull-downmenu of theDistribution column. 11. Enter the sweep parameters:
l Start = 1.6GHz l Stop = 2.6GHz l Count = 11.
12. Click thePreview button to display the Sweepwindow:
Figure 3-4: Sweep PointsWindow – Discrete Sweep
13. Close theSweep Pointswindow. 14. SelectGenerate surface current, underOptions in theEdit Frequency Sweep dialog box.
Note:
For discrete sweeps, optionally generating surface currents enables you to view currents and calculate far field effects at multiple frequencies in later post-pre- cessing steps. For interpolating sweeps you can optionally save surface current data for only the last adaptive pass of the solution frequency. For fixedmesh ana- lyses, you cannot save surface current data.
15. ClickOK to add the discrete sweep and close theEdit Frequency Sweep dialog box.
Explore Disabling Sweeps and Setups ANSYS Electronics Desktop lets you to disable/enable sweep and setup definitions independently.
Disable or Enable a Sweep Definition:
To enable/disable a frequency sweep definition, right-click the sweep in the Project Manager and chooseEnable Sweep Analysis orDisable Sweep Analysis, whichever option is present:
Figure 3-5: Disable Sweep Analysis Option
Note:
You can also disable a sweep by double-clicking it in the Project Manager (or right-clicking and selectingProperties from the shortcut menu) to open theEdit Frequency Sweep dialog box. In the upper-right corner of this dialog box, deselect theEnabled option and clickOK to apply the change. (To reactivate the sweep, simply re-open theEdit Fre- quency Sweep dialog box, select theEnabled option, and clickOK.)
Disable or Enable a Setup Definition: To enable/disable a setup definition, right click the setup in the Project Manager and choose Enable Setup Analysis orDisable Setup Analysis, whichever option is available:
Figure 3-6: Disable Setup
Note:
You can also disable an analysis setup by double-clicking it in the Project Manager (or right-clicking and selectingProperties from the shortcut menu) to open thePlanarEM Setup dialog box. Below theSetup Name text box, deselect theEnabled option and click OK to apply the change. (To reactivate the setup, simply re-open thePlanarEMSetup dialog box, select theEnabled option, and clickOK.)
When you disable an analysis setup, any sweep associated with it has no effect, even though the sweep is still enabled.
View the Mesh You can view the layout of the design within the Layoutwindow in a number of planar or 3D views. If you've closed the Layoutwindow or opened other windows in front of it, such as a 2D report plot, you can quickly return to the Layoutwindow as follows:
l From themenu bar, clickHFSS 3D Layout> Layout Editor. This commandwill reopen the window if it has been closed or bring it to the front if it's already open.
l Or, when the Layoutwindow is still open but hidden by other windows, select it from theWin- dowmenu to bring it to the front.
In the Layoutwindow, you can view themesh in either of two ways:
l In the Project Manager, click to select the setup (such asPlanarEMSetup 1). Then, from the menu bar, clickHFSS 3D Layout> Solution Setup> Pre-Process Geometry> Display.
l In the Project Manager, right-click the setup and selectPre-Process Geometry> Display from the shortcut menu.
Either of the preceding two options displays a 3D mesh on themodel in the Layout window. The mesh display honors layer visibility; that is, themesh will not be displayed on a layer that is not visible. If there are self-intersectingmesh edges, these are highlighted in bold yellow.
To hide themesh, repeat the command from either access point and toggle off theDisplay option. However, for now, leave themesh visible and proceed to the next topic. You can hide themesh later.
Explore Dynamic Mesh Updates In the previous topic, you learned how to display themesh. The Layout editor allows you to change the shape of the objects you've drawn by select them and then clicking and dragging grips on the edges (such asmidpoint and endpoint grips). This feature enables you to freelymove, stretch, com- press, or skew object shapes. Additionally, you can add or remove objects from themodel. By default, themesh is not dynamically updated when you change the geometry in any of these ways. Therefore, after adding, deleting, or altering any geometry, you would have to refresh the displayed meshmanually using one of the follow methods:
l In the Project Manager, right-click the analysis setup (such asPlanarEMSetup 1) and choosePre-Process Geometry> Refresh from the shortcut menu.
l Select the analysis setup in the Project Manager. Then, from themenu bar, clickHFSS 3D Layout> Solution Setup> Pre-Process Geometry> Refresh.
Important:
The consolidation of surfaces into a conformal mesh is skipped for dynamic and tolerant meshing, including for light weight geometries. This can lead to overlapping surfaces in SBR+ simulations. The user should carefully avoid overlapping surfaces or objects as SBR+ can produce unexpected results.
Dynamic Updates: By enabling theDynamic Updates feature, themesh will automatically refresh whenever you alter the geometry in anyway. You can enable this feature in either of two ways:
l In the Project Manager, right-click the analysis setup (such asPlanarEMSetup 1) and choosePre-Process Geometry> Dynamic Updates from the shortcut menu.
l Select the analysis setup in the Project Manager. Then, from themenu bar, clickHFSS 3D Layout> Solution Setup> Pre-Process Geometry> Dynamic Updates.
Either of these actions toggles the state of theDynamic Updates option. That is, the feature is enabled if currently disabled, and the feature is disabled if currently enabled.
Feel free to experiment by displaying themesh, enablingDynamic Updates, and then adding new geometry or distorting existing geometry to see themesh refresh itself. Afterward, use the Undo command, which is available onmultiple ribbon tabs, to revert to the correct model configuration. Be careful not to undo tomany operations, or your sweeps, analysis setup, or port definitionswill be undone. If you do go too far, click Redo to restore the desiredmodeling and setup steps.
Important:
It is a good idea to save themodel first and avoid saving it during the experiment. In this way, you can close the alteredmodel (without saving it) and reopen the saved version if necessary.
When finished, deactivate thePre-Process Geometry> Display option to hide themesh.
Run the Analysis 1. To sequentially run all analysis setups and associated frequency sweeps that exist in the
design, take one of the following actions:
l On theSimulation ribbon tab, click Analyze. l From themenu bar, clickHFSS 3D Layout> Analyze. l In the Project Manager, right-clickAnalysis and chooseAnalyze from the shortcut menu.
Alternatively, you can run a single sweep: In theAnalysis branch of the Project Manager, right-click the appropriate sweep and chooseAnalyze from the shortcut menu.
Figure 3-7: Analyzing a Single Sweep
2. ClickShow Progress in the status bar at the bottom of the programwindow to display the solution progress (if the window is not already displayed).
3. Check the status while the analysis is running.
The following additional actions are possible:
l While the simulation is running, you canPause orAbort it through the shortcut menu that appears when you right-clicking in theProgresswindow.
l TheClean Stop command completes the computation of the current frequency point before stopping the analysis.
l To alter the priority of a particular simulation, right-click theProgresswindow, click Change Priority, and then select the appropriate setting (Highest, Above Normal, Normal, Below Normal, or Lowest Priority).
Figure 3-8: Changing the Priority of the Analysis Solution
Note:
Altering the priority of a solution can be useful when you aremultitasking on the computer. It can help to free up resources from a computationally intensive application so that other programs perform adequately. Conversely, it can prevent less important programs from excessively slowing down the more intensive application.
4 - Evaluate the Results (Post-Pro- cessing)
Use the post-processing capabilities of ANSYS Electronics Desktop to display the results of a simulation. You can also use the export features to save the analysis data (and an equivalent circuit) in various industry-standard file formats.
The topics for this section include:
l View SMatrix Data l Plot Return Loss l Plot a User DefinedGraph l Revise p2 Excitation and Animate Current Results l Frequency Animated Far Field Plot
View S Matrix Data You can review the scatter matrix (S Matrix) data at all sweep frequencies or at a selected frequency as the solution progresses. You can also review Y and ZMatrix data andmore. Here, you will look at the S Matrix data for all frequencies in Sweep 1, as follows:
1. In the Project Manager, right-clickSweep1, and selectResults> Matrix data.
TheSolutions dialog box appears.
2. Ensure that only theS Matrix option is selected under theProfile tab.
Evaluate the Results (Post-Processing) 4-1
3. Select theDisplay All Freqs. option. Your results should be similar to the following figure:
Figure 4-1: Solutions Dialog Box – Sweep 1 S Matrix Data
4. Select the Format tab and then choose the desired data format from the drop-downmenu (for example,Magnitude/Phase(deg), dB/Phase(deg), Real, or Imaginary).
5. Select theExport tab and clickExport Matrix Data.
TheExport Network Data Solution dialog box appears.
a. Select the preferred file format (Save as type) – for example, Touchstone(*.sNp) or Neutral Model Format (*.nmf).
b. Optionally, customize the File name, if desired. c. The default save location is the same folder where themodel resides. However, you
can navigate to an alternative folder is desired. d. ClickSave or clickCancel to abort the operation.
6. To export the circuit as an equivalent SPICE model, clickEquivalent Circuit Export.
Note:
SPICEmodels require solution data at DC (0Hz) conditions, so a warningmessage is encountered for this sweep.
a. Select the desired location, format, and other equivalent circuit options. b. ClickOK to save the exportedmodel orCancel to abort the operation.
7. To see run time data pertaining to the analysis, click theProfile tab. 8. Close theSolutions dialog box.
Plot Return Loss To create a report:
1. First, open theReport dialog box by using one of the following threemethods:
l On theResults ribbon tab, click Standard Report> 2D. l Using themenu bar, clickHFSS 3D Layout> Results> Create Standard Report> Rectangular Plot.
l In theProject Manager, right-clickResults and chooseCreate Standard Report> Rectangular Plot from the shortcut menu.
TheReport dialog box openswith the Trace tab selected.
2. Plot the return loss: a. From theSolution drop-downmenu, selectPlanar EM Setup 1 : Sweep 1. b. In theCategory, Quantity, and Function lists, selectS Parameters, S(p1, p1) and
dB, respectively. c. ClickNew Report and then clickClose.
Figure 4-2: S-Parameter Plot, dB(S(p1,p1)) - Return Loss
For additional details about formatting the plot (for example, labeling the axes and changing the trace color) see theGenerating Reports and Postprocessing section of the help.
Plot a Smith Chart Next, you will display a Smith chart for S(p1, p1). The Smith chart is a convenient means of simultaneously displayingmultiple parameters (such as impedance, reflection coefficients, scattering parameters, constant gain contours, andmore). It is a useful graphical aid for electronics engineers working in the radio frequency disciplines. The chart was invented by Phillip H. Smith
1. On theSimulation ribbon tab, click Standard Report> Smith Chart.
TheReportdialog box openswith the Trace tab selected.
Note:
Aswith the previous plot (Return Loss), this chart and other plot commands can also be accessed from other locations (HFSS 3D Layoutmenu andProject Man- ager: Results shortcut menu).
2. From theSolution drop-downmenu, selectPlanar EM Setup 1 : Sweep 1. 3. In theCategory, Quantity, and Function lists, selectS Parameters, S(p1, p1), and
<none>, respectively. 4. ClickNew Report andClose.
The Smith Chart appears:
Figure 4-3: Smith Chart
Revise p2 Excitation and Animate Current Results Before creating an overlay of the current results and animating it, you will alter the edge port definition for port p2. The default configuration applies an identical 1 volt magnitude excitation at 0 degrees phase angle to both of the ports that you added (p1 and p2). You will now set the p2 excitation to 0 volts, essentiallymaking p1 the input of the low pass filter and p2 the output for the pur- pose of the overlay.
To revise the p2 excitation:
1. In the Project Manager, under Excitations, double-clickp2.
TheEdge Port Definition dialog box appears:
2. InPost Processing Settings section, enter 0V and 0deg, respectively, for theMagnitude andPhase values.
Figure 4-4: Edge Port Definition Dialog Box – Port p2
The following controls are also available:
Port Definition settings:
l PortName specifies the port being defined l Terminal Name controls the name of the terminal l Reference specifies the reference used by the port l Calibration Zo equivalent to the Full Port Impedance of the port and expressed in Ohms
Planar EM settings:
l Type of port l Ignore Reference allows you to chooseUse Port Solver l Use Port Solver should be selected if you want the characteristic impedance and propagation constant for the port to be calculated. The gap source is automatically cal- ibrated for greater accuracy.
l Use Default should be selected if, instead of the Port Solver, you want the default setting to be used (expressed in Ohms).
HFSS section:
Post Processing settings:
l Magnitude expressed in Volts (V) l Phase expressed in degrees l Post Process Port allows you to specify theRenormalize Impedance andDeembed Distance settings
l Renormalize Impedance expressed in ohms l Deembed Distance expressed inmm l Deembed Gap Port Inductance specifies that the inductance of the port is calculated and cached as part of the solution data for subsequent use. During post processing a list of the ports to deembed is used to calibrate the network data.
Note:
For more information, seeDeembedding in the help.
3. When all settings are as desired, clickOK to close the dialog box.
Note:
Alternatively, the followingmethod is convenient for multi-port designs. You can right-clickExcitations in the Project Manager and selectPort Excitations from the shortcut menu. ThePort Excitations dialog box appears, in which you can modifymultiple port excitations.
Figure 4-5: Edit Port Excitations Dialog Box
Note:
Renormalization is ignored if it is set to zero, but de-embedding is still honored. The following warningmessage is produced for all ports with a zero post-processing renormalization impedance:
Zero impedance on port '<arg1>' is ignored; renormalization will by skipped for this port.
Display and Animate the Currents:
4. In the Project Manager, right-clickField Overlaysand selectPlot PEM Fields> Mag_Sru- faceJ.
TheCreate Field Plot dialog box appears.
Note:
The only Solution available for selection isPlanar EM Setup1:Sweep2, since only the discrete sweep type has the option to output currents.
5. In the Intrinsic Variables section, select 2.1GHz from the F (frequency) pull-downmenu. This is the frequency that most closely corresponds to the point of minimum return loss on the S Parameter plot.
6. Accept the remaining options and clickDone.
TheSelect Geometry dialog box appears, where you specify on which layers you wish to overlay the current results.
7. Select the t1 layer and clickOK.
The current overlay should resemble the following figure:
Figure 4-6: Surface Current Overlay @ 2.1 GHz – t1 Layer
8. In the Layoutwindow, double-click within the current overlay legend to access the J Surf plot settings.
9. In theColor map tab, choose Temperature from theSpectrum drop-downmenu:
Figure 4-7: J Surf Plot Settings – Color map Tab
10. Select theScale tab andmake the following changes: a. Specify 21 forNum. Divisions b. Select the Log option to produce a logarithmic scale. c. SelectUse Limits. d. ForMin, specify 0.05. e. ForMax, specify 26.
Figure 4-8: J Surf Plot Settings – Scale Tab
11. In the Project Manager, under Field Overlays> J Surf, right-clickMag_SurfJ1 and click Animate.
TheCreate Animation Setup dialog box appears.
12. Specify the following animation settings: a. Ensure that Single Variable andPhase are selected from theSwept Variable(s)
pull-downmenus. b. In theStart, Stop, andSteps text boxes, enter 0deg, 360deg, and 37, respectively.
These settingswill result in an animation with 10 degree phase increments.
Figure 4-9: Setup Animation Dialog Box
13. ClickOK. A control panel opens, and the animation begins:
Figure 4-10: Animation Dialog Box
14. You can use the animation controls to pause, restart, reverse, or change the speed of the animation.
15. In the Layoutwindow, use the various tools to Zoom, Rotate, or Pan the animation.
The resulting animation should resemble the one shown below:
Figure 4-11: Resulting Current Animation
16. In theAnimation dialog box, clickClosewhen finished.
Frequency Animated Far Field Plot Far fields are not usually of interest when designing a filter, but the procedure is shown here for reference. Current outputs are required as the basis of far field computations. So that the currents are saved, and the currents and fields results are available for you to plot, one of the following two con- ditionsmust bemet:
l Run a discrete sweep with theGenerate surface current option selected in theSweep setup. In this case, you can specifymultiple discrete frequency points and will have the currents and fields available for all specified frequencies. Aswith the current animation, you can define the frequency at which you view the far field results. Additionally, you can animate far field results based on the available frequencies. That is, the video time line progresses from one frequency to the next (as opposed to progressing through the range of phase angles as the basis of the animation).
l Run an adaptivemesh or advanced adaptivemesh analysis with theSave currents for last adaptive pass option enabled in theAnalysis setup. In this case, the current and field results are only available for the last adaptive pass of the specified solution frequency.
In order to plot far field results, you have to define an Infinite Sphere far field setup underRadiation in the Project Manager.
Define an Infinite Sphere and Plot the Far Field Results:
1. In the Project Manager, right-clickRadiation and choose Insert Far Field Setup> Infinite Sphere.
The Infinite Sphere Setup dialog box appears:
.
Figure 4-12: Infinite Sphere Setup Dialog Box
2. Accept the default setup and clickOK to add the far field setup.
3. On the Results ribbon tab, click Far Fields Report> 3D Polar.
TheReportwindow appears. Notice that the Solution andGeometry parameters are already set with the only available choices that provide far field results:PlanarEMSetup 1 : Sweep 2 and Infinite Sphere 1, respectively. Also, theCategory, Quantity, and Function settings have defaulted to Far Field, Etotal, and <none>, respectively, which are the desired settings for this report.
4. Select the Families tab and then click the elipsis button ( ) in theEdit column of the Families table.
5. In the pop-up dialog box that appears, select the frequency, 2.1GHz, which corresponds most closely to the point of minimum return loss:
Figure 4-13: Choosing the Frequency for the Far Field Plot
6. ClickNew Report and then clickClose.
Note:
You can also access this command in the following alternative ways:
l Right-clickResults in the Project Manager and chooseCreate Far Fields Report> 3D Polar Plot from the shortcut menu.
l Using themenu bar, clickHFSS 3D Layout> Results> Create Far Fields Report> 3D Polar Plot.
The Far Field Plot 1window appears, and the far field pattern is displayed. Rotate, zoom, and/or pan for a good view point of themodel:
Figure 4-14: Far Field Plot (Etotal)
Overlay the Far Field Pattern on the Model Geometry: To better see how the far field pattern relates to the low pass filter geometry, overlay the pattern on themodel in the Layout window, as follows:
7. UnderResults in theProject Manager, right-clickFar Field Plot 1 and selectOverlay Vis- ibility.
8. Adjust themodel viewpoint as desired. Themodel layout and overlay should resemble the following figure:
Figure 4-15: Far Field Pattern Overlay
Note:
The plot legend and the color contours applied to the trace layer of themodel still correspond to the surface current plot created earlier. Optionally, to avoid con- fusion, you could right-clickMag_SurfaceJ1, under Field Overlays> J Surf in the Project Manager, and deselectPlot Visibility in the shortcut menu. This action hides the J Surf color contour and the associated legend.
Frequency Animate the Far Field Plot:
9. Use theWindowmenu to select the Far Field Plot 1window, bringing it to the foreground. 10. Right-click in the Far Field Plot 1window and chooseView> Animate.
TheCreate Animation Setup dialog box appears:
11. Ensure that the settings in the dialog boxmatch the following figure and then clickOK.
Figure 4-16: Setup Far Field Animation with Frequency as Sweep Variable
The Animation control panel appears and the far field plot animation begins to play:
Figure 4-17: Far Field Plot 1 Animation
12. Use the animation controls to pause, restart, reverse, or change the speed of the animation. 13. In theAnimation dialog box, clickClosewhen finished.
14. Save the project and exit ANSYS Electronics Desktop.
Congratulations, you've completed theHFSS 3D Layout: Low Pass Filter exercise.
Table of Contents
HFSS 3D Layout in ANSYS Electronics Desktop
Set Up an HFSS 3D Layout Design
2 - Create the Model
Set Up Frequency Sweeps
View the Mesh
View S Matrix Data
Frequency Animated Far Field Plot

Getting Started with HFSS 3D Layout: Low Pass Filter

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Transcript of Getting Started with HFSS 3D Layout: Low Pass Filter