Getting Started with HFSS: Silicon Spiral

Inductor

Release 18.1
ANSYS, Inc. April 2017
Southpointe
2600 ANSYS Drive ANSYS, Inc. and
Canonsburg, PA 15317 ANSYS Europe,
ansysinfo@ansys.com Ltd. are UL
http://www.ansys.com registered ISO
9001:2008 com-
(T) 724-746-3304 panies.
(F) 724-514-9494
Getting Started with HFSS: Silicon Spiral Inductor

Copyright and Trademark Information

2017 ANSYS, Inc. Unauthorized use, distribution or duplication is prohibited.
ANSYS, ANSYS Workbench, Ansoft, AUTODYN, EKM, Engineering Knowledge Manager,
CFX, FLUENT, HFSS and any and all ANSYS, Inc. brand, product, service and feature names,
logos and slogans are registered trademarks or trademarks of ANSYS, Inc. or its subsidiaries in
the United States or other countries. ICEM CFD is a trademark used by ANSYS, Inc. under
license. CFX is a trademark of Sony Corporation in Japan. All other brand, product, service and
feature names or trademarks are the property of their respective owners.
Disclaimer Notice
THIS ANSYS SOFTWARE PRODUCT AND PROGRAM DOCUMENTATION INCLUDE
TRADE SECRETS AND ARE CONFIDENTIAL AND PROPRIETARY PRODUCTS OF
ANSYS, INC., ITS SUBSIDIARIES, OR LICENSORS. The software products and doc-
umentation are furnished by ANSYS, Inc., its subsidiaries, or affiliates under a software license
agreement that contains provisions concerning non-disclosure, copying, length and nature of use,
compliance with exporting laws, warranties, disclaimers, limitations of liability, and remedies, and
other provisions. The software products and documentation may be used, disclosed, transferred,
or copied only in accordance with the terms and conditions of that software license agreement.
ANSYS, Inc. is certified to ISO 9001:2008.
U.S. Government Rights
For U.S. Government users, except as specifically granted by the ANSYS, Inc. software license
agreement, the use, duplication, or disclosure by the United States Government is subject to
restrictions stated in the ANSYS, Inc. software license agreement and FAR 12.212 (for non-DOD
licenses).
Third-Party Software
See the legal information in the product help files for the complete Legal Notice for ANSYS pro-
prietary software and third-party software. If you are unable to access the Legal Notice, please
contact ANSYS, Inc.

2
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Conventions Used in this Guide

Please take a moment 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 copy must be typed, then a space must be typed, and then
file1 must be typed.
o On-screen prompts and messages, names of options and text boxes, and menu com-
mands. Menu commands are often separated by carats. For example, click HFSS>Ex-
citations>Assign>Wave Port.
o Labeled keys on the computer keyboard. For example, Press Enter means to press the
key labeled Enter.
l Italic type is used for the following:
o Emphasis.
o The titles of publications.
o Keyboard entries when a name or a variable must be typed in place of the words in italics.
For example, copy file name the word copy must be typed, then a space must 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.
l Toolbar buttons serve as shortcuts for executing commands. Toolbar buttons are displayed
after the command they execute. For example,

On the Draw menu, click Line means that you can click the Draw Line toolbar button
to execute the Line command.
Getting Help: ANSYS Technical Support
For information about ANSYS Technical Support, go to the ANSYS corporate Support website,
http://www.ansys.com/Support. You can also contact your ANSYS account manager in order to
obtain this information.
All ANSYS software files are ASCII text and can be sent conveniently by e-mail. When reporting
difficulties, it is extremely helpful to include very specific information about what steps were taken
or what stages the simulation reached, including software files as applicable. This allows more
rapid and effective debugging.
Help Menu
To access online help from the menu bar, click Help and select from the menu:
l HFSS Contents - click here to open the contents of the online help.
l HFSS Search - click here to open the search function of the online help.

3
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Context-Sensitive Help
To access online help from the user interface, do one of the following:
l To open a help topic about a specific menu command, press Shift+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 press F1.

4
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Table of Contents
Table of Contents Contents-1
1 - Introduction 1-1
Sample Project - Silicon Spiral Inductor 1-1
2 - Set Up the Project 2-1
Launch Electronics Desktop 2-1
Set Tool Options 2-2
Insert HFSS design 2-3
Set Model Units 2-4
Set Solution Type 2-4
3 - Set Up Si Spiral Inductor 3-1
Create 3D Model for Dielectrics 3-1
Create Substrate 3-2
Create Oxide 3-4
Create Passivation 3-6
Create Air Body 3-8
Assign Radiation Boundary 3-9
Create Ground 3-11
Assign Perfect E Boundary to the Ground 3-12
Hide Dielectrics 3-13
Create Spiral Inductor Geometry 3-13
Create Offset Coordinate System 3-15
Create Spiral Path 3-15
Create Polyline Freehand 3-15
Create Polyline from the Status Bar 3-18
Assign Thickness to the Spiral 3-20
Create Underpass 3-21
Create Via1 3-22
Create Via2 3-23

Contents-1
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Create Feed 3-24

Unite Spiral Objects 3-25
Seed Mesh Conductors 3-26
Create Ground Ring 3-28
Create Inner Ring 3-29
Complete the Ring 3-30
Create Extension 1 3-31
Create Extension 2 3-32
Create Source 1 3-33
Create Source 2 3-33
Group the Conductors 3-34
Assign Excitation for Source1 3-34
Assign Excitation for Source2 3-35
Show All 3-36
Boundary Display (Optional) 3-36
4 - Analyze Spiral Conductor 4-1
Create Analysis Setup 4-1
Add a Frequency Sweep 4-3
Model Validation 4-5
Analyze the Model 4-6
Review Solution Data 4-6
Review the Profile Panel 4-6
Review the Convergence Panel 4-8
Review the Matrix Data Panel 4-8
Review the Mesh Statistics Panel 4-9
Generate Reports 4-9
Create S-parameter vs. Frequency Plot 4-9
Custom Equations Output Variables 4-11
Use Output Variables for Next Report 4-14
Simulate with Solve Inside Conductors 4-16

Contents-2
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Results with Solve Inside 4-17

Contents-3
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Contents-4
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

1 - Introduction
This document is intended as supplementary material to HFSS for beginners and advanced users.
It includes instructions to create, simulate, and analyze a silicon spiral inductor model.
This chapter contains the following topic:
l Sample Project - Silicon Spiral Inductor

Sample Project - Silicon Spiral Inductor

In this project, we will use HFSS to create, simulate, and analyze a 2.5 turn spiral inductor.

Figure 1-1 Spiral Inductor

This nominal design consists of the following components with their corresponding dimensions:
l Spiral: 2.5T, W=15um, S=1.5um, Rad=60um.
M6, 2um, = 2.8e7 S/m.
l Underpass: M5, 0.5um, = 2.8e7 S/m.
l Stackup: Passivation: 0.7um, r = 7.9.
l Oxide: 9.8um, r = 4.0.
l Substrate: 300um.
r = 11.9, = 10 S/m.

Introduction 1-1
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 1-2 Passivation, Oxide and Substrate

Introduction 1-2
ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

2 - Set Up the Project

This chapter contains the following topics:
l Launch HFSS
l Set Tool Options
l Insert HFSS design
l Set Model Units(cm)
l Set Solution Type(Terminal)

Launch Electronics Desktop

Store a shortcut of the ANSYS Electronics Desktop application on your desktop.
1. Double-click the ANSYS Electronics Desktopicon to launch the application.

Set Up the Project 2-1

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 2-1 Electronics Desktop launched

Note If the application does not list the folder, go to File and click New. If the Project Man-
ager window does not appear, go to View and enable it.

Set Tool Options

Verify the options under the Tools menu as follows:
1. Go to Tools>Options>General Options.
The Options dialog box appears.

Figure 2-2 Assignment Options

2. Click Boundary Assignment to ensure all Assignment Options are checked.
3. Click 3D Modeler Options.
The Modeler Options dialog box appears.
4. Click Drawing and ensure the Automatically cover closed polylines option is selected.

Set Up the Project 2-2

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 2-3 The option on the Operation tab

5. Again, on the Drawing tab check Edit properties of new primitives and click OK.

Figure 2-4 option on the Drawing tab

Note This option causes a Properties dialog box to appear automatically whenever you cre-
ate a new object.

Insert HFSS design

The icon represents the Insert HFSS design (IHd) option.
1. Expand the project tree.
2. If IHd is present, proceed to rename and save the project and if it is absent click the IHd icon
to include it.
Note Inclusion of IHd modifies the project and hence the asterisk appears on Projectn.

Set Up the Project 2-3

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 2-5 IHd included

3. Click Project_n*, hit F2, rename the project as si_spiral_inductor, and save it.

Set Model Units

Set the units for the geometric model as follows:
1. On the HFSS toolbar, click Modeler> Units.
The Set Model Units dialog box appears.
2. Select the unit as um and click OK.

Figure 2-6 Set Model Units dialog

Set Solution Type

To set the solution type:
1. On the toolbar, click HFSS> Solution Type
The Solution Type dialog box appears.

Set Up the Project 2-4

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 2-7 Solution Type dialog

2. Select Driven Terminal and click OK.
Note Driven Terminal calculates the terminal-based S-parameters of multi-conductor trans-
mission line ports. The S-matrix solutions will be expressed in terms of terminal voltages and
currents.

Set Up the Project 2-5

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

PDF layout 2-6

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

3 - Set Up Si Spiral Inductor

This chapter describes how to build the 3D spiral inductor model in HFSS.
This chapter contains the following topics:
l Create 3D Model for Dielectrics
l Create Substrate
l Create Oxide
l Create Passivation
l Create Air Body
l Assign Radiation Boundary
l Create Ground
l Assign Perfect E Boundary to the Ground
l Create Spiral Inductor Geometry
l Assign Thickness to the Spiral
l Create Underpass
l Create Via1
l Create Via2
l Create Feed
l Unite Spiral Objects
l Solve Inside Conductors
l Seed Mesh Conductors Set for Solve Inside
l Create Ground Ring
l Create Inner Ring
l Complete The Ring
l Create Extension1
l Create Extension2
l Create Source1
l Create Source2
l Group the Conductors
l Assign Excitation for Source1
l Assign Excitation for Source2

Create 3D Model for Dielectrics

To create the 3D model, you must draw a number of objects. The following sections contain the
steps to create the geometry.

Set Up Si Spiral Inductor 3-1

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Create Substrate
To create the substrate, first draw a box freehand as follows:
1. Click Draw>Box.
The cursor is accompanied by a black square box.
2. Click inside the Modeler window to establish the x,y axes and drag the mouse to draw a rect-
angle
3. Click the mouse to establish the z axis and drag the mouse along the z-axis to draw the
height.
4. Click the mouse again, to complete the box.
The Properties dialog box appears.

Figure 3-1 Properties dialog

5. Edit the fields in the Command dialog box as in "View/Edit Material dialog " on the facing
page.
6. On the Attribute, enter Sub in the Name field and from the Materials drop-down menu,
select Edit.
The Select Definition dialog box appears.

7. Click Add Material and edit the fields in the dialog box as shown in the following figure.

Note:Mainly change relative permittivity to 11.9 and bulk conductivity to 10 siemens/m.

Set Up Si Spiral Inductor 3-2

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-2 View/Edit Material dialog

8. Click OK to close the View/Edit Material dialog box and repeat the same on the other dialog
boxes to exit.
9. Do Ctrl+D to fit the view.
.

Set Up Si Spiral Inductor 3-3

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-3 Substrate created

Create Oxide
To create the oxide, first draw a box and specify its size and location as follows:
1. Draw the box freehand.
The Properties dialog box appears.

Figure 3-4 Command dialog for Oxide

2. On the Command tab, edit the fields as in "Command dialog for Oxide" above and click
Attribute and rename box to: Oxide
3. From the Materials drop-down menu, select Edit.
The Select Definition dialog box appears.
4. Click Add Material and edit the fields as in "View/Edit Material dialog" on the facing page.
Note The View/Edit Material dialog box appears.

Set Up Si Spiral Inductor 3-4

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-5 View/Edit Material dialog

5. Click OK to close the View/Edit Material dialog box and repeat the same on the other dialog
boxes to exit.

Set Up Si Spiral Inductor 3-5

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-6 Oxide Substrate

Create Passivation
To create passivation, draw a box and specify its size and location as follows:
1. Draw the box freehand.

Figure 3-7 Command tab for passivation

2. On the Command tab edit the fields as shown in "Command tab for passivation" above and
on the Attribute tab rewrite the Name field to Pass.
3. Select Edit from the Materials drop down menu.
4. Click Add Material and edit the fields as in the following figure.

Set Up Si Spiral Inductor 3-6

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-8 View/Edit Material dialog

5. Click OK to close the View/Edit Material dialog box and repeat the same on the other dialog
boxes to exit.

Set Up Si Spiral Inductor 3-7

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-9 Passivation applied

Create Air Body

To create an air body, draw a box and specify its size and location as follows:
1. Draw a box freehand.
2. Set the Command dialog box as in the following figure.

Figure 3-10 Properties dialog for Air

3. On the Attribute tab, rename object to Air.
4. Ensure that the Material selected is vacuum and click OK.
The box gets updated with the new dimensions and properties that you set.

Set Up Si Spiral Inductor 3-8

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-11 Air Enclosure drawn

Assign Radiation Boundary

Now assign the radiation boundary to the air box.
1. Select Air from the History Tree dialog box.
The air body gets highlighted.
2. Right click Air and select Assign Boundary>Radiation from the short-cut menu.
The Radiation Boundary dialog box appears.
3. Edit the fields as shown in the figure below and click OK.

Set Up Si Spiral Inductor 3-9

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-12 Radiation Boundary

Set Up Si Spiral Inductor 3-10

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-13

Create Ground
To create the ground, draw a rectangle as described below.
1. Click Draw> Rectangle.
2. Draw a rectangle freehand.
The Properties dialog box appears.
3. Click OK to accept the values in the Properties dialog box.
4. Double-click CreateRectangle from the history tree.
The Command dialog box appears.

Set Up Si Spiral Inductor 3-11

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-14 Properties for Rectangle

5. Edit the fields as shown in "Properties for Rectangle" above.
The rectangle updates itself with the new settings.
6. Double-click Rectangle1 in the history tree and on the Attribute dialog box enter Ground in
the Name field and click OK.

Figure 3-15 The structure with rectangle drawn

Assign Perfect E Boundary to the Ground

1. Click outside the structure to deselect all 2D and 3D objects.
2. Select Ground from the history tree to highlight it.
3. Right-click Ground and select Assign Boundary>Perfect E from the short-cut menu.
The Perfect E Boundary dialog box appears.
4. Enter PerfE_Ground in the Name field.

Set Up Si Spiral Inductor 3-12

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-16 Perfect E boundary dialog

5. Leave the Infinite Ground Plane unchecked and click OK.
The Perfect E boundary is applied and the Message Manager gives the following warning:
l Boundary Rad1 and Boundary PerfE_Ground overlap.
This is because you applied the PerfE boundary on a face that already has the Radiation
boundary. However, PerfE_Ground overrides the Radiation boundary on that face owing to
a higher priority.
Note By default priority is assigned according to the order in which the boundaries are
applied. Since PerfE_Ground was assigned after Rad1, it has a higher priority. HFSS lets
you re-prioritize the boundaries, but it is not needed for this project.

Hide Dielectrics
1. Click Edit>Select All Visible
2. Click View>Visibility>Hide Selection>All Views
All the objects are now hidden.

Create Spiral Inductor Geometry

Before you create the spiral inductor, set the default material.

Set Up Si Spiral Inductor 3-13

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

1. From the Modeler Materials toolbar, choose Select.

The Select Definition dialog box appears.
2. Click Add Material.
The View/Edit Material dialog box appears.
Edit the fields as shown in the following figure.

Figure 3-17 View/Edit Material dialog

3. Click OK to close the View/Edit Material dialog box and repeat the same on the other dialog
box to exit.

Set Up Si Spiral Inductor 3-14

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Create Offset Coordinate System

1. Click Modeler>Coordinate System>Create>Relative CS>Offset
2. In the coordinate fields, enter the origin as follows:
X:0.0, Y: 0.0, Z:304.8.
Note The co-ordinate fields appear on the status bar at the bottom and are titled Select the
origin.
3. Press Enter.

Create Spiral Path

To create the spiral draw a Polyline using one of the following methods:
l Create Polyline Freehand
l Create Polyline From the Status Bar

Create Polyline Freehand

This section shows how to create the spiral by drawing it free hand and then, editing its coordin-
ates.
1. Click Draw>Line.
2. Click anywhere in the modeler to establish the first point and drag the cursor to draw a line
and click again, to establish the second point as shown in the figure below.

Figure 3-18
3. Continue to drag and click the mouse to establish 13 such points as shown in the figure
below where we have labeled all the 13 points.
4. Right click and select Done from the short cut menu.

Set Up Si Spiral Inductor 3-15

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-19 Polyline with 13 points

5. Double-click CreateLine from the history tree and edit the coordinates for the vertices in its
Segment tab as shown below.

Figure 3-20 Coordinates for Line1

6. Edit the fields for each of the 12 CreateLine options on their corresponding Segment tabs
as shown below.

Set Up Si Spiral Inductor 3-16

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-21 Coordinates for Line 2 through Line 7

Set Up Si Spiral Inductor 3-17

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-22 Coordinates for Line 8 through Line 12

Create Polyline from the Status Bar

In this method, enter the coordinates of the points in the status bar as described below.
1. Click Draw>Line.
2. Edit the coordinate entry fields as follows:
Enter the vertex field for point 1:

Set Up Si Spiral Inductor 3-18

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

X: -67.5, Y: 7.5, Z: 1.0 Press the Enter key.

Enter the vertex field for point 2:
X: -67.5, Y: -67.5, Z: 1.0 Press the Enter key.
Enter the vertex field for point 3:
X: 84.0, Y: - 67.5, Z: 1.0 Press the Enter key.
Enter the vertex field for point 4:
X: 84.0, Y: 84.0, Z: 1.0 Press the Enter key.
Enter the vertex field for point 5:
X: - 84.0, Y: 84.0, Z: 1.0 Press the Enter key.
Enter the vertex field for point 6:
X: - 84.0, Y: -84.0, Z: 1.0, Press the Enter key.
Enter the vertex field for point 7:
X: 100.5, Y: -84.0, Z: 1.0, Press the Enter key.
Enter the vertex field for point 8:
X: 100.5, Y: 100.5, Z: 1.0, Press the Enter key.
Enter the vertex field for point 9:
X: - 100.5, Y: 100.5, Z: 1.0, Press the Enter key.
Enter the vertex field for point 10:
X: - 100.5, Y: - 100.5, Z: 1.0, Press the Enter key.
Enter the vertex field for point 11:
X: 117.0, Y: -100.5, Z: 1.0, Press the Enter key.
Enter the vertex field for point 12:
X: 117.0, Y: 0.0, Z: 1.0, Press the Enter key.
Enter the vertex field for point 13:
X: 131.0, Y: 0.0, Z: 1.0, Press the Enter key.
3. Using the mouse, right-click and from the short-cut menu select Done.
4. Select Attribute and enter Spiral in the Name field and click OK.

Set Up Si Spiral Inductor 3-19

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-23 Spiral drawn

Assign Thickness to the Spiral

To assign trace width and thickness perform the following:
1. Right-click Create Polyline under Spiral from the History Tree.
2. Select Properties from the short-cut menu.
The Properties dialog box appears.

Figure 3-24 History Tree

Set Up Si Spiral Inductor 3-20

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-25 Command dialog box

3. Edit the fields as shown in "Command dialog box" above. and click OK to close the Prop-
erties dialog box.
The spiral is assigned the thickness that you set.

Figure 3-26 The updated spiral

Create Underpass
Before creating the underpass ensure the grid plane is XY as follows:
1. Click Modeler>Grid Plane>XY.

Set Up Si Spiral Inductor 3-21

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-27 Properties dialog (underpass)

2. Draw a box freehand and edit the fields on the Command tab as shown in "Properties dia-
log (underpass)" above. .
3. On the Attribute tab rename object as Underpass and click OK to close the Properties dia-
log box.

Figure 3-28 The Underpass

Create Via1
To create the Via, first draw a box.
1. Draw a box freehand and on the Command tab edit the fields as shown in "Properties dia-
log Via1" on the facing page. .
2. On the Attribute tab enter Via1 in the Name field and click OK.

Set Up Si Spiral Inductor 3-22

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-29 Properties dialog Via1

Figure 3-30 Via1 applied

Create Via2
To create another via, again, draw a box.
1. Draw a box freehand and edit the fields on the Command tab as shown in "Via2
Properties" below. .

Figure 3-31 Via2 Properties

Set Up Si Spiral Inductor 3-23

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

2. On the Attribute tab enter Via2 in the Name field and click OK.

Figure 3-32 Via2 applied

Create Feed
1. Draw a box freehand.
The Properties dialog box appears.

Figure 3-33 Feed Properties

2. Edit the fields as shown in "Feed Properties" above. and on the Attribute tab enter Feed in
the Name field and click OK to close the Properties dialog box.
3. Do Ctrl+D to fit the view.

Set Up Si Spiral Inductor 3-24

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-34 Feed applied

Unite Spiral Objects

You will now unite the spiral objects.
1. Click Spiral, press the Ctrl key and select Via1, Via2, Feed, and Underpass.

Figure 3-35 The pieces united

Set Up Si Spiral Inductor 3-25

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Note The order in which you select the objects determines the name of the united structure.
For example if you select spiral first followed by the rest, the united structure will be named
spiral. If you select Feed first, then, the united structure will be named as Feed.
2. Click Modeler>Boolean>Unite

Figure 3-36 The united object names itself as spiral

3. Do Ctrl+D to fit the view.
4. Double-click spiral from the history tree and make sure Solve Inside is unchecked
on the Attribute tab.
Note The conductive material is represented by a boundary condition that removes the need
to solve inside metal.

Seed Mesh Conductors

In this section you will set HFSS to refine the length of the tetrahedral elements for the spiral until
they are below the specified value.
1. Click Edit>Select All Visible and select Spiral.
2. Click HFSS> Mesh Operations>Assign>Inside Selection>Length Based
The Element Length Based Refinement dialog box appears.
3. Edit the fields as shown in the figure below and click OK.

Set Up Si Spiral Inductor 3-26

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-37 Element Length Based Refinement settings

Set Up Si Spiral Inductor 3-27

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-38

Create Ground Ring

To create a ground ring, first draw a box freehand.
1. Click Draw>Box.
2. Draw a box freehand.
The Properties dialog box appears.

Set Up Si Spiral Inductor 3-28

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-39 Ring Properties

3. On the Command tab edit the fields as shown in "Ring Properties" above.
4. On the Attribute tab enter Ring in the Name field and select Edit from the Materials drop-
down menu.
The Select Definition window appears.
5. Type pec in the Search by Name field.
6. Click OK to close the View/Edit Material dialog box and repeat the same on the other dialog
boxes to exit.

Figure 3-40 Select Definition window

Figure 3-41 Ring applied

Create Inner Ring

To create the inner ring, again draw a box.

Set Up Si Spiral Inductor 3-29

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

1. Click Draw>Box.
2. Draw a box freehand.
The Properties dialog box appears.
3. On the Command tab, edit the fields as shown in "The Properties dialog box for Inner Ring"
below. .

Figure 3-42 The Properties dialog box for Inner Ring

4. On the Attribute tab enter Inner in the Name field and ensure that the Material assigned is
pec and click OK.

Figure 3-43 Inner ring drawn

Complete the Ring

1. Click Edit>Select>By Name
The Select Object dialog box appears.

Set Up Si Spiral Inductor 3-30

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-44 Select Object dialog box

2. Select Ring, press the Ctrl key and click Inner and click OK.
3. Click Modeler>Boolean>Subtract
The Subtract dialog box appears.
4. Verify Ring is in the Blank Parts and Inner in the Tool Parts and click OK.
Post subtraction, the structure should resemble the one in "The subtracted ring" below. .

Figure 3-45 Subtract dialog box

Figure 3-46 The subtracted ring

Create Extension 1
1. Draw a box freehand.
The Properties dialog box appears.
2. On the Command tab edit the fields as shown in "Extension1 properties" on the next page. .
3. On the Attribute tab enter the Name as Ring_Ext1, ensure that pec is selected from the
Material drop-down and click OK.

Set Up Si Spiral Inductor 3-31

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-47 Extension1 properties

Figure 3-48 The Ring_Ext1 applied

Create Extension 2
1. Draw a box freehand.
The Properties dialog box appears.
2. Edit the fields as shown in "Properties dialog box for Ring_Ext2" below. .

Figure 3-49 Properties dialog box for Ring_Ext2

3. On the Attribute tab enter the Name as Ring_Ext2 and click OK.

Set Up Si Spiral Inductor 3-32

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-50 Ring_Ext2 applied

Create Source 1
1. Draw the rectangle freehand.
The Properties dialog box appears.
2. Click OK to accept the current settings.
3. Double click CreateRectangle from the history tree.
4. Edit the fields in the Command dialog box as in the following figure.

Figure 3-51 Command dialog box for Source1

5. Click Attribute and enter Name type as Source1 and click OK.

Create Source 2
1. Draw the rectangle freehand.
The Properties dialog box appears.
2. Click OK to close the dialog box.
3. Under Rectangle1, double click CreateRectangle from the history tree.
4. Edit the fields as shown in the following figure.

Set Up Si Spiral Inductor 3-33

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-52 Command dialog box for Source2

5. Double-click Rectangle1 and enter Source2 in the Name field and click OK.

Group the Conductors

1. Click Edit>Select>By Name
2. In the Select Object dialog box, select the Ring, Ring_Ext1, Ring_Ext2
3. Click OK.
4. Click Modeler>Boolean>Unite
5. Do Ctrl+D to fit the view.

Assign Excitation for Source1

We will use wave ports to excite source1:
1. Click Source1 from the history tree.
Source1 gets highlighted in the structure.

Set Up Si Spiral Inductor 3-34

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-53 Reference Conductor Terminal dialog box

2. Right click Source1, and select Assign Excitation>Assign>Lumped Port
Reference Conductor for Terminals dialog box appears.
3. Set the options as shown in "Reference Conductor Terminal dialog box" above. and click
OK.

Assign Excitation for Source2

To select the object Source2:
1. In the History tree, expand the Unassigned objects tree.
2. Select Source2.

Set Up Si Spiral Inductor 3-35

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-54 History Tree

To assign lumped port excitation
1. Click HFSS>Excitations>Assign>Lumped Port
2. Enter 2 for the Port Name.
3. Set the rest of the options as in "Reference Conductor Terminal dialog box" on the previous
page. and click OK.

Show All
To show all objects do the following:
1. Click View>Visibility>Show All>All Views
2. Do Ctrl+D to fit the view.

Boundary Display (Optional)

Boundary display/solver view provides a snapshot of all boundaries in the model including ports
and surface residing on the surrounding background object. It can be very useful for diagnosing
problems with design setups.
1. Click HFSS>Boundary Display (Solver View)
The Solver View of Boundaries dialog box appears.
Note HFSS identifies all the unique boundary conditions and ports to display where the
boundaries are physically located in the model.
2. Select the boundaries you wish to view from the dialog box as shown in "Solver View of
Boundaries dialog box" on the facing page. .
The choices made here will show the boundaries in the Modeler field. See "Solver Bound-
aries selected" on the facing page. .

Set Up Si Spiral Inductor 3-36

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 3-55 Solver View of Boundaries dialog box

Figure 3-56 Solver Boundaries selected

Note If you double-click the fields under Color, you can change the color as you want from
the palette that appears. The background is displayed as the outer boundary and the perfect
conductors are displayed as the smetal boundary.

Set Up Si Spiral Inductor 3-37

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

PDF layout 3-38

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

4 - Analyze Spiral Conductor

This chapter describes how to run the simulation and generate reports.
This chapter contains the following topics:
l Create Analysis Setup
l Add Frequency Sweep
l Model Validation
l Analyze the Model
l Solution Data
l Profile
l Convergence
l Matrix Data
l Mesh Statistics
l Generate Reports
l Create S-Parameter vs Frequency Plot
l Custom Equations Output Variables
l Use Output Variables for Next Report

Create Analysis Setup

To create an analysis setup:
1. Click HFSS>Analysis Setup>Add Solution Setup
The Add Solution Set-up dialog box appears.

Analyze Spiral Conductor 4-1

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-1 Solution Set-up window

2. In the Solution Setup window: click the General tab.
3. Edit the fields as shown in "Solution Set-up window" above.
4. Click Options, edit the fields as in the figure below and click OK.

Analyze Spiral Conductor 4-2

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-2 Options tab

Add a Frequency Sweep

1. Click HFSS>Analysis Setup>Add Sweep
The Edit Frequency Sweep dialog box appears.
2. Enter the following fields in Edit Frequency Sweep dialog box as shown in the figure below.

Analyze Spiral Conductor 4-3

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-3 Edit Frequency Sweep

3. Click the Interpolationtab and edit the fields as in shown in the figure below and click OK.

Analyze Spiral Conductor 4-4

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-4 Interpolation

Model Validation
Before running the simulation your model must pass the Validation Check.
To validate the model:
1. Click HFSS>Validation Check

Analyze Spiral Conductor 4-5

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-5 Validation Check

2. Verify whether your dialog box is the same as Figure 5.
3. Click Close.
Note: For this project, ignore warnings as no action is required.

Analyze the Model

To start the solution process:
1. Click HFSS>Analyze All
Note Change the design name to No_Solve_Inside(Driven Terminal) and then, save the pro-
ject si_spiral_inductor.

Review Solution Data

To view the Solution Data:
1. Click HFSS>Results>Solution Data
2. Click Profile, Convergence, Matrix Data etc to see those panels and the results they con-
tain.

Review the Profile Panel

The Profile window lets you view a synopsis of the simulation results ranging from mesh creation
and refinement to information about the different adaptive passes, the matrix assembly and solve
along with extraction of electromagnetic field and SYZ parameter data. The more highly refined
the mesh, i.e. higher the number of tetrahedra, more accurate is HFSS solution of the design gen-
erating optimum results. However, there is a trade-off in the number of tetrahedra used and the
computational resources required. Higher the number of tetrahedra the more accurate the solu-
tions. Keep in mind that increased accuracy requires more computational resources and more
time.

Analyze Spiral Conductor 4-6

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-6 Profile

Analyze Spiral Conductor 4-7

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Review the Convergence Panel

To view the Convergence data click the Convergence tab.
Note: The default view is for convergence is Table. Select the Plot radio button to view a graph-
ical representations of the convergence data.

Figure 4-7 Convergence dialog box

Review the Matrix Data Panel

To view matrices computed for the S-parameters, impedances, and propagation constants during
each adaptive, non-adaptive, or sweep solution, click the Matrix Data tab.

Analyze Spiral Conductor 4-8

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-8 Matrix Data

Note: To view a real-time update of the Matrix Data, set the Simulation to Setup1, Last
Adaptive.

Review the Mesh Statistics Panel

As the title indicates this panel shows statistics of the mesh, more specifically, it gives break-ups of
the tetrahedra used to solve the different components of the model and their size and data.

Figure 4-9 Mesh Statistics

Generate Reports
The subsequent sections describe how to create different reports, customize the equations for the
Y axis and create output variables.

Create S-parameter vs. Frequency Plot

1. Click HFSS>Results>Create Terminal Solution Data Report>Rectangular Plot
The Report dialog box appears.

Analyze Spiral Conductor 4-9

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-10 Report dialog box

2. Edit the fields as shown in "Report dialog box" above. .
3. Click New Report and Click Close.

Analyze Spiral Conductor 4-10

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-11 The XY Plot

Custom Equations Output Variables

1. Click HFSS>Results>Create Terminal Solution Data Report>Rectangular Plot
The New Report dialog box appears.
2. Click Output Variables.

Figure 4-12 Output Variables dialog box

3. Enter Q11 in the Name field.
4. Select Terminal Y Parameters from Category.
5. Select Yt(Source1_T1, Source1_T1) as Quantity.
6. Select im from the Function list.
7. Click Insert Quantity into Expression.
8. Type the forward slash(/).

Analyze Spiral Conductor 4-11

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-13 Expression

Note Notice the expression is in red ink because it is incomplete. The slash causes HFSS to
expect another function. Red ink indicates inaccuracy or incompleteness.
9. Select Yt(Source1_T1, Source1_T1) in the Quantity field.
10. Select Function:re
11. Click Insert Quantity into Expression.
12. Click Add.
The output variable Q11 is added to the list.
13. Create Q22 with Yt(Source2_T1, Source2_T1) as quantity.
14. Click Add.
.

Figure 4-14 Output Variables set

15. Click Done.
The Output Variables dialog box closes.
16. Edit the fields in the Report dialog box as in "Report dialog box" on the facing page. .
17. Click New Reports and click Close.

Analyze Spiral Conductor 4-12

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-15 Report dialog box

Analyze Spiral Conductor 4-13

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-16 Y parameters versus Frequency

Use Output Variables for Next Report

To use Output Variables for another report:
1. Click HFSS>Results>Create Terminal Solution Data Report>Rectangular Plot
2. In the New Report window, Trace Tab click the Output Variables button
3. In the Output Variables dialog box enter these values:
l Name:L11
l Type -1/(2*pi*freq* in the Expression field.
l Select Terminal Y Parametersfrom Category.
l Select Yt(Source1_T1, Source1_T1) from Quantity.
l Clickim from the Function list.
4. Click Insert into Expression.
5. Type a bracket ) key and click Add.

Figure 4-17 New Report dialog box

Analyze Spiral Conductor 4-14

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-18 Output Variables dialog box

6. Click Done to close the Output Variables dialog box.
7. Edit the fields in Report dialog box as shown in the following figure.

Figure 4-19 Report dialog box

8. Click New Report and click Close.

Analyze Spiral Conductor 4-15

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-20 L11 versus Frequency

Simulate with Solve Inside Conductors

In this section, we will select simulate the design with Solve Inside selected for the spiral. By
default Solve Inside gets unchecked for metals or highly conductive materials. In such cases, the
conductive material is represented by a boundary condition that removes the need to solve inside
the metal. For most projects, we recommend that you use the default settings for Solve Inside.
When Solve Inside is selected it includes tetrahedra inside a conductor for simulation which may
require a large mesh. Solve Inside can be useful for low frequency analysis of electrically small
projects for enhanced accuracy of sensitivity design parameters such as the Q factor.
1. In the Project Manager window select the design and copy it.

2. Go the project folder and paste the design.

3. Rename the pasted design.

4. Double-click spiral from the history tree and select Solve Inside in the Attribute dialog
box.
The Message Manager displays the following message: Solving inside a solid with high con-
ductivity may require a large mesh.
Note For this project, ignore this message.
5. Right click the design and select Analyze All from the short-cut menu.

Analyze Spiral Conductor 4-16

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Results with Solve Inside

All the plots get updated real time as the simulation takes place. For this design it may take more
passes to converge than when Solve Inside was unchecked.

Figure 4-21 Convergence Plot

Analyze Spiral Conductor 4-17

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
Getting Started with HFSS: Silicon Spiral Inductor

Analyze Spiral Conductor 4-18

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.
 Getting Started with HFSS: Silicon Spiral Inductor

Figure 4-22 Plot with Solve Inside

Analyze Spiral Conductor 4-19

ANSYS Electromagnetics Suite 18.1 - ANSYS, Inc. All rights reserved. - Contains proprietary and confidential
information of ANSYS, Inc. and its subsidiaries and affiliates.