【AWR中文】EM 仿真案例教程
EM仿真案例教程——Creating a Distributed Interdigital Filter
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1CREATING A DISTRIBUTED INTERDIGITAL FILTER (3)
1.1C REATING A N EW P ROJECT (3)
1.2C REATING AN EM S TRUCTURE (4)
1.3S ETTING U P THE E NCLOSURE (5)
1.4S IDEWALL B OUNDARY C ONDITIONS (7)
1.5A DDING C ONDUCTORS TO THE L AYOUT (8)
1.6A DDING V IAS (12)
1.7V IEWING THE S TRUCTURE IN 3D (15)
1.8A DDING P ORTS AND D E-EMBEDDING L INES (15)
1.9S PECIFYING THE S IMULATION F REQUENCIES (18)
1.10V IEWING S TRUCTURE M ESH (18)
1.11R UNNING THE EM S IMULATOR (20)
1.12D ISPLAYING R ESULTS ON A G RAPH (21)
1.13C HANGING F REQUENCY R ANGE AND S TEP S IZE (22)
1.14A NIMATING C URRENTS AND E-FIELDS (23)
1.15C OMPLETING THE F ILTER L AYOUT (26)
1.16A DDING A P ORT (30)
1.17A DVANCED F REQUENCY S WEEP (31)
1.18A DDING AN EM S TRUCTURE TO A S CHEMATIC AND S IMULATING (33)
2关于未尔 (35)
1 Creating a Distributed Interdigital Filter
This example demonstrates how to use Microwave Office to simulate a distributed microstrip interdigital filter using the EM simulator.
The basic procedures in this example include:
?Creating an EM structure
?Setting up an enclosure
?Creating a layout
?Modeling via holes
?Viewing a structure in 3D
?Defining ports and de-embedding lines
?Configuring structure mesh
?Viewing current density and electric fields
?Performing Advanced Frequency Sweep (AFS)
?Adding EM structure into schematic and simulating
1.1 Creating a New Project
The example you create in this chapter is available in its complete form as EM_example.emp in your C:\Program Files\AWR\AWR2008\Examples directory. To access this file from a list of Getting Started example projects, choose File > Open Example, Ctrl-click the Keywords column header and type "getting_started " in the text box at the bottom of the dialog box. You can use this example file as a reference.
To create a project:
1.Choose File > New Project.
2.Choose File > Save Project As. The Save As dialog box displays.
3.Navigate to the directory in which you want to save the project, type
"EM_example" as the project name, and then click Save.
To import a Layer Process File (LPF):
1.Choose Project > Process Library > Import LPF. The Import Process
Definition dialog box displays.
2.Navigate to the program directory (C:\Program Files\AWR\AWR2008 is
the default installation directory). If you have changed the default installation, then browse to that directory instead.
3.Choose the Blank.lpf file and click Open, then click Yes to the
prompt to replace the existing LPF.
1.2 Creating an EM Structure
To create an EM structure:
1.Choose Project > Add EM Structure > New EM Structure. The New EM
Structure dialog box displays.
2.Type "Interdigital Filter" and select the AWR EMSight Simulator from
the list of EM Simulators available on your computer, then click
Create. An EM structure window displays in the workspace.
NOTE: EMSight uses a rectilinear grid for defining structures. When
you set up designs, use the coarsest grid possible when defining
structures, as this provides faster simulation time (usually without any compromise in simulation accuracy.) Other third-party EM
simulators may only use the grid for drawing purposes and the density may not matter-- see the third-party simulator documentation for
further details.
1.3 Setting Up the Enclosure
The enclosure defines the material types, all the dielectric materials for each of the layers in an EM structure, sets the boundary conditions, and defines the overall physical size of the structure and minimum grid units used to specify conductor materials in the structure.
To set up the enclosure:
1.Choose Options > Project Options. The Project Options dialog box
displays.
2.Click the Global Units tab and select the Metric units check box,
then set the Length type to mm and click OK.
3.Choose Options > Layout Options. The Layout Options dialog box
displays.
4.Click the Layout tab, and under Grid Options set the Grid Spacing to
"1" mm and the Database unit size to "0.01"mm, then click OK. If a
warning message displays, click Yes.
5.In the Project Browser, under EM Structures and "Interdigital Filter",
double-click Enclosure. The Element Options - ENCLOSURE Properties
dialog box displays.
6.Click the Enclosure tab and type "12" in X_Dim, type "12" in Y_Dim,
type "0.2" as the Grid_X, and type "0.2" in Grid_Y.
To define the materials:
1.Click the Material Defs tab.
2.Click Add for Dielectric Definitions. The Add Dielectric dialog box
displays. Set the parameters as shown in the following figure and
then click OK.
3.Click Add for Conductor Definitions. The Add Conductor dialog box
displays. Choose Gold as Presets and then click OK. Your dialog box should display as shown in the following figure. Make sure to select the Color as shown
To define the dielectric layers of the enclosure:
box.
2.Select 1 under Layer #. Type "5" in the Thickness column, select Air
under Material Def., and type "1" in the Draw Scale column.
3.Select 2 under Layer #. Type "0.636" in the Thickness column, select
Alumina under Material Def., and type "4" in the Draw Scale column.
1.4 Sidewall Boundary Conditions
In EMSight, the boundary conditions for the sidewalls of the enclosure are always perfect conductors and cannot be modified. Third-party simulators may make other assumptions for the sidewall boundary conditions-- for details, see the vendor documentation for the solver used. The boundary conditions for the Top Boundary and Bottom Boundary of the enclosure have default perfect conductors, but they can be modified. Notice the stackup figure in the Enclosure Properties dialog box changes when you select a different boundary condition. You do not modify the default boundary conditions in this example.
To assign material types for the conductors and vias:
2.Click Insert. Under Name, replace Trace1 with "Gold Line", enter
"0.001" as Thickness , and select Gold as Material Def, for the 1um
thick gold line, and then click OK.
1.5 Adding Conductors to the Layout
You use the MWO EM Layout Editor to draw physical structures for simulation. You can also import structures directly from the AWR schematic layout tool, or import structures from AutoCAD DXF or GDSII. In this example you draw
the physical layout of a microstrip interdigital filter using the EM Layout Editor.
To draw the physical layout:
1.Click the Layout tab in the lower left window and select Conductor.
2.Select 2 as the EM Layer, and Gold Line as the Material.
3.Click theRectangle button on the Draw Tools toolbar to add a
rectangular conductor.
4.Move the cursor into the Interdigital Filter window, click the top of
the window to make it active, and press the Tab key. The Enter
Coordinates dialog box displays.
5.Type "0" as the value of x and "7.8" as the value of y, and then
click OK.
6.Press the Tab key again to display the Enter Coordinates dialog box.
Ensure that the Re (relative) check box is selected, type "2.2" as
the value of dx, and "0.6" as the value of dy, and then click OK. A
rectangular conductor displays in the EM structure window.
To draw a second rectangular conductor:
1.Click the Rectangle button on the toolbar.
2.Move the cursor into the Interdigital Filter window and press the Tab
key. The Enter Coordinates dialog box displays. Type "4" as the value of x and "1.4" as the value of y, and then click OK.
3.Press the Tab key again to display the Enter Coordinates dialog box.
Type "1.2" as the value of dx and "7.2" as the value of dy, and then click OK. A second rectangular conductor displays in the EM structure window.
To move the second rectangular conductor next to the first conductor:
1.Click the second rectangular conductor. The rectangle is highlighted.
2.Slide the cursor over the selected conductor until the cursor
displays as a cross.
3.Click and hold down the mouse button. A dx, dy readout displays in
the window, as shown in the following figure.
NOTE: You can click the Ruler button on the toolbar to measure the
dimension of conductors, offsets, or spaces in an EM structure layout.
4.Drag the cursor until the dx, dy readout displays dx: -1.8 and dy: 1,
then release the button to place the rectangle.
1.6 Adding Vias
Vias are interconnects between substrate layers. You must add a via to
ground from one side of the larger conductor to the bottom of the enclosure. To add a via:
1.In the Layout Manager, select Via.
2.Select Gold Line as the Material and 1 as the Extent.
3.Click the Rectangle button on the toolbar.
4.Choose Draw > Add Via Port.
5.Move the cursor into the Interdigital Filter window, click the top of
the window to make it active, and press the Tab key. The Enter
Coordinates dialog box displays. Type "2.6" as the value of x and "9.4" as the value of y, and then click OK.
6.Press the Tab key again to display the Enter Coordinates dialog box.
Type "0.4" as the value of dx and "-0.8" as the value of dy, and then click OK. A via displays in the Interdigital Filter window.
7.Choose Edit > Copy, then choose Edit > Paste.
8.Move the mouse into the EM structure window. An outline of the copied
via displays.
9.Right-click once to rotate the via.
10.Press the Tab key to display the Enter Coordinates dialog box.
Deselect Rel to activate absolute coordinates. Type "2.8" as the x value and "9" as the y value, and then click OK. The new EM structure displays as follows.
11.Click near the top left corner of the resonator, and hold down the
mouse button while dragging the cursor down and to the right so the dashed box encompasses the vias, then release the mouse button. The two vias are selected.
12.Choose Draw > Modify Shapes > Union to unify the two rectangular vias.
1.7 Viewing the Structure in 3D
The EM simulator supports multiple 2D (structure) and 3D views.
To create a 3D view:
1.Choose View > View EM 3D Layout . A window containing the 3D view
displays in the workspace.
2.Choose Window > Tile Vertical. The views display side-by-side.
NOTE: To change the view of a 3D structure, right-click in the 3D
window and choose Zoom Out, View Area, or View All.
3.To rotate a 3D structure, click anywhere in the 3D window and
continue to hold down the mouse button while you move the mouse.
1.8 Adding Ports and De-embedding Lines
The EM simulator can have electrical ports defined at the edge of the
defining box (edge ports) or as a via probe coming in from the top or
bottom surfaces (via ports).
To define an edge port:
1.Click the smaller conductor in the EM structure window.
2.Choose Draw > Add Edge Port.
3.Position the cursor to the left edge of the small conductor until the
outline of a square displays, and click to place the port. A box with the number 1 (indicating port 1) displays at the left edge of the
conductor.
To subtract (de-embed) an amount of electrical length from the simulation results, the reference plane for the port must be moved away from the edge of the box.
To de-embed 1.6 mm of electrical length on port 1:
1.Right-click in the EM structure window and choose View Area.
2.With the cursor displayed as a magnifying glass, click and drag the
cursor around port 1 and the small conductor. The window zooms in on the selected area.
3.Click port 1. Four squares display at its corners.
4.Move the mouse over the edge of the port until the cursor displays as
a double arrow.
5.Click and hold down the mouse button to display a dx and dy readout.
6.Drag the cursor to the right until the dx, dy readout displays dx:
1.6 and dy: 0. Release the mouse button to place the de-embedding
line.
1.9 Specifying the Simulation Frequencies
To specify the simulation frequencies:
1.In the Project Browser, right-click "Interdigital Filter" under EM
Structures and choose Options. The Options dialog box displays.
2.Click the Frequencies tab.
3.Clear the Use project defaults check box to give local frequency
settings precedence over global project frequency settings.
4.Ensure that GHz displays in Data Entry Units.
NOTE: You can define the simulation frequency globally (by choosing
Options > Project Options and clicking the Frequencies tab) or
locally using these steps. It is best to use the local frequency
settings for EM structures as you typically want to sweep EM
structures with fewer frequency points than with linear circuits.
Data is obtained at the project frequencies using interpolation
and/or extrapolation.
5.Specify the Start, Stop and Step values shown in the following figure,
click Apply to display the values in Current Range, and then click OK.
1.10 V iewing Structure Mesh
Meshing of a structure is very important before simulation. The style of mesh largely affects the simulation time. Loosely meshed structures take much less time to simulate than tightly meshed structures, but the results may not be very different. Thus it is recommended to start with the coarsest possible grid and gradually make it finer until the result does not change significantly. You can view mesh by adding annotation to the structure; it is displayed in the 3D View.
To view mesh:
1.In the Project Browser, right-click "Interdigital Filter" under the
EM Structures node and choose Add Annotations. The Add Annotation
dialog box displays.
2.Select EM_MESH from the Measurement list and set the parameters as
shown in the following figure, then click OK.
3.Make the 3D view window active. Click the Top button on the toolbar
for the top view, and the mesh displays as follows.
1.11 R unning the EM Simulator
The EM simulator is very fast for electrically small structures. To find
the resonant frequency of the first resonator of the filter, you can run an EM simulation on the initial layout of the Interdigital Filter EM structure.
To simulate the structure:
1.Under EM Structures and "Interdigital Filter", double-click
Information. The Solver Information dialog box displays if EMSight is
the selected simulator. The estimated solve time for the EM structure
and other information displays, depending on the selected solver. For
more information about the data displayed for third-party simulators,
see the vendor documentation.