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1
Introduction to The
Layout Environment
Microwave Office Training
2 Introduction to Layout
MWO Layout
Schematic View
Schematic Layout View
Circuit
Artwork Cells
Two views of the same circuit!
- including connectivity (ratslines)
“Dumb” Polygons - no notion of connectivity
External World
•GDSII
•DXF
Need Cell Faces or Cell PinsNote: Two different layout environments - This
is the most misunderstood concept in layout!
External World
Need Export Mapping
2
3 Introduction to Layout
Modeling and Drawing Layers
Model Layers Drawing Layers
GDS File Layers
EM Layers
Line Type
Artwork Cell
User Drawn Shape
Parameterized Layout Cell
12
Transistor with associated Artwork Cell
NO SCHEMATIC LINK
We need to understand how this works
4 Introduction to Layout
Drawing Layers
Model Layers Drawing Layers
GDS File Layers
EM Layers
Line Type
Artwork Cell
User Drawn Shape
Parameterized Layout Cell
12
Transistor with associated Artwork Cell
NO SCHEMATIC LINK
Start with Drawing Layers
3
5 Introduction to Layout
Drawing Layers - 2
Drawing Layers
The rule is: If you “see” it - it’s a drawing layer.
Schematic Layout View Artwork Cells
12
We can control:
• The number of layers and Names
•The order they are drawn
•Color, Line, Fill Pattern
This is setup in the LPF (layout process file).
- Can work directly with the file (ASCII)
- or work with most of it through the UI (recommended)
6 Introduction to Layout
The LPF File
• The Layout Process File
– Units, Layout Resolution,...
– Layers: Names, Colors, Patterns,...
– Model Mapping Files
– PCells: Transmission Lines, Via, ...
• User Interface (UI) in the Software
– Easier to work in the UI
– Can do everything but PCell setup
– Can see colors, patterns,...
• Can work directly with file
– Can copy between different projects
– We’ll focus on this when looking at lines and vias
Every Project has an LPF File
4
7 Introduction to Layout
The LPF File - Units
Under Project Options
Tip - Don’t Change Units After Starting a Project!
(Otherwise - all your lengths will be odd numbers.)
Can also set in: Options > Project
Options > Global Units
8 Introduction to Layout
The LPF File - Database and Layout Resolution
• Database Resolution
– All shapes are stored internally in nm
• Can’t make shape smaller than this
– For English Units - mils
• Converts using 25.4 microns / mil
• Don’t go below 0.01 mils - or will lose precision
• Layout Resolution
– Grid Spacing
• For Snapping, etc.
– Resolution
• Smallest non-zero distance
• Tip - Set to ½ the process tolerance
– Export Issues LaterSet in: Options > Layout Options > Layout
5
9 Introduction to Layout
Example Board Stackup
•FR4 - Epsr = 3.38, tand = .003 @ 1 GHz
•Conductors - Copper, Thickness = 1.4 mil
•Dielectric Layers - 25 mil thick
Microstrip
Ground and
Coplanar Lines
Stripline
Ground AWR_Bottom_Ground
AWR_Mid_Copper
AWR_Mid_Ground
AWR_Top_Copper
AWR_PCB3
AWR_PCB2
AWR_PCB1
AWR_Via34
AWR_Via23
AWR_Via12
Metal LayersDielectric LayersVia Layers
Tip: Use easy to identify names! (These all have AWR_ in
front of them.) Helps when layers are added.
Let’s work with this Library
10 Introduction to Layout
A New Project with a Library
Step 1: Create a new project - importing the AWR_4Layer_PCB library.
Browse for the file: pcb_template/4layerPCB.ini
6
11 Introduction to Layout
Using Drawing Layers
Step 2: Create a new schematic - “Shapes”.
- Open up its schematic layout view.
Schematic Design Toolbar
Note: Can also open it up:
by RC on schematic icon and Open Layout.
Schematic LayoutSchematic
12 Introduction to Layout
Using Drawing Layers - 2
Schematic View
Schematic Layout View
Circuit
Artwork Cells
Two views of the same circuit!
- including connectivity (ratslines)
“Dumb” Polygons - no notion of connectivity
External World
•GDSII
•DXF
Need Cell Faces or Cell PinsNote: Two different layout environments - This
is the most misunderstood concept in layout!
External World
Need Export Mapping
We are here!
7
13 Introduction to Layout
Using Drawing Layers - 3
Step 3: Open up the layout browser - by making sure layout is the selected tab at the bottom left of the UI.
This is the drawing layer browser.
Step 4: Select a layer and draw a shape in the layout schematic.
Note: Select the layer by clicking on the colored rectangle.
Draw Tools Toolbar.
14 Introduction to Layout
The LPF Drawing Layers - 1
• The LPF file contains the drawing layers
• They can be viewed and modified in the lpfviewer
– Layout Tab and upper left of layout browser.
8
15 Introduction to Layout
The LPF Drawing Layers - 3
Tip: Put Error
Layer at Top
Tip: Use Easily Identifiable Names
MWO will put
items on top
layer if it
doesn’t know
what to do
Make it a
bright color
16 Introduction to Layout
Cloaking and Visibility
Cloaking - You won’t see the
layer in the layout browser
Visibility controls seeing the
layer - it’s the same as the
light bulb on or grayed out
This system layer (Annotation) is
Visible but cloaked in the
browser
Avoids clutter and mistakes
Q: So how did I draw it?
A: I drew it on another
layer - and switched it’s
properties to Annotation!
9
17 Introduction to Layout
The LPF Drawing Layers - 4
Tip: Cloak the
System Layers
MWO has
certain
system
layers it
needs
But keep them Visible!
18 Introduction to Layout
The LPF Drawing Layers - 5
Line - The
border color
and pattern
Fill - Color
and pattern
When Freeze Layer - Shapes can’t be moved - same as
light bulb crossed out (right click - Toggle Freeze)
10
19 Introduction to Layout
The LPF Drawing Layers - 6
Drawn First
Drawn Last
Tip: solid layer might hide other layers
Drawn FirstDrawn First
Not Solid
Solid
Very important for
Negative Layers.
20 Introduction to Layout
Drawing Layers - Configurations
• Can have different configurations saved
– drawing layers are the same
– visibility, cloaking, colors, can be different
• Can use for customizing look/feel of layers– Example - only want signal layers showing for routing.
– Example - Want critical layers highlighted with bright color.
Set on right side of drawing
layer setup
Can have several
different configurations
Step 5: Create a configuration that only has the metal layers visible, and the signal layers uncloaked. Call it “Signals
Only”.
Try it - why do your shapes dissapearwhen you select them?
11
21 Introduction to Layout
Setup the 3D Layers
Vertical Position of
Bottom of LayerThickness of Layer
Units Are Same as Project Units (mils)
Used by the 3D view of Layout
Blend - controls
how
transparent a
layer is
0 - completely
1 - opaque
transparent
opaque
Tip - A layer of 0 thickness
won’t draw anything.
Textures - “Skin”
over the surface
22 Introduction to Layout
Textures
• Must be set for Opaque
• Puts a bit map on the surface - *.bmp file
– File is located in $MWO/textures/
• Texture scale sets how “grainy” the bitmap is.
Need texturing turned on
Schematic 3D Toolbar
12
23 Introduction to Layout
Modeling Layers
Model Layers Drawing Layers
GDS File Layers
EM Layers
Line Type
Artwork Cell
User Drawn Shape
Parameterized Layout Cell
12
Transistor with associated Artwork Cell
NO SCHEMATIC LINK
Modeling Layers
24 Introduction to Layout
The External Layout World
Everything is on Layers
Example: GDSII - Shapes
•54_0 (is Metal1)
•128_0 (is Error)
•...
Example: DXF - Lines, Shapes
•Metal1
•Error
•...
To Motivate Modeling layers ...
13
25 Introduction to Layout
Simple Approach - Use One Set of Layer Definitions
Schematic
Artwork Cells
Final LayoutExternal
World
26 Introduction to Layout
BAD IDEA
Schematic
Artwork Cells
Final LayoutExternal
World
What about
GDSII? DXF?
What if the
Vendor/Layers
Change?
Different Model for Each layer - Ex.
Stripline?
What if I need extra
or fewer layers?
The names are
impossible to
remember
I have both IC and Board
14
27 Introduction to Layout
Modeling Layers - 2
• So - we use model layers.
• Can’t “see” them... but...
• They act as a “buffer” or mapping to the drawing layers.
• Why?
– Gives us more flexibility.
• Many model layers to one drawing layer.
• Can have multiple mapping files.
• Used in a variety of ways.– Import of GDSII and DXF.
– Used with PCells (which for transmission lines also use linetypes). Get to this a bit later ...
28 Introduction to Layout
Import of GDSII and DXF
Schematic View
Schematic Layout View
Circuit
Artwork Cells
Two views of the same circuit!
- includingconnectivity (ratslines)
“Dumb” Polygons - no notion of connectivity
External World
•GDSII
•DXF
Need Cell Faces or Cell PinsWe are down here!
15
29 Introduction to Layout
Modeling Layers - 3
• DXF and GDSII import into the artwork cell layout (not schematic layout!).
• MWO looks for a model layer with same layer name as in DXF/GDSII file.
• If it finds it...
– Draws on drawing layer that the model layer maps to.
• If it doesn’t ...– Creates a model layer and draws on new drawing layer of same
name...
• Note - You know about all you need to know to work artwork cells and import/export! (Cell Libraries in a bit...)
Importing DXF and GDSII into Artwork Cells
30 Introduction to Layout
Modeling Layers - 4
Step 6: Import the DXF cell library - mypad.dxf
Note: DXF Import asks for units. GDSII doesn’t.
(because DXF has no notion of an unit.)
Cell libraries are controlled at the top of the layout browser. RC on Cell libraries - Import
DXF Library to bring in the cell library.
16
31 Introduction to Layout
Model Layers - 5
The software is looking for model layers with the same names as the DXF (GDSII) layers.
- Warning you it can’t find them...
1. It creates model layer and maps to draw layer of same name.
Adds the library and cell.
32 Introduction to Layout
Model Layers - 6
Step 7: Change the mapping so that Topmetal -> AWR_Top_Copper
The Model mapping can be used to put shapes on the right drawing layers.
Before
TopMetal
After
Model Layer Mapping
AWR_Top_Copper
17
33 Introduction to Layout
Model Layers - 7
Artwork Cells - DXF
Showing Model Layers for DXF (ex. TopMetal).
Artwork Cells - GDSII
Shows only valid GDSII Model layer names and mapping to Drawing layer
Schematic Layout
Draw Layers
34 Introduction to Layout
Bad Things Can Happen If You Don’t Understand...
Only 7 Layers Used
Three Top Metal Layers?
Error in the middle?
GDS
Numbers?
Colors
Repeated
18
35 Introduction to Layout
Schematic Layout
• How do we draw on schematic layout?
• 3 ways:
– 1: Can draw “dumb” polygons ...
• Examples - ground fill, text, package outline,...
• Can copy and paste artwork cells.
– 2: Schematic elements and subcircuits that have been given layout by associating a fixed artwork cell with them.
– 3: PCells
• Transmission Lines
• Other PCells - Vias, Thin film resistors, thin - film caps
• Note: A PCell (Parameterized Cell) is a layout cell that has parameters that affect it’s layout:
– Example: MLIN - has parameters width, length.
– Typically PCells come with your supplied libraries.
36 Introduction to Layout
MWO Layout
Schematic View
Schematic Layout View
Circuit
Artwork Cells
Two views of the same circuit!
- includingconnectivity (ratslines)
“Dumb” Polygons - no notion of connectivity
External World
•GDSII
•DXF
Need Cell Faces or Cell Pins
External World
Need Export Mapping
We are here!
19
37 Introduction to Layout
Schematic Layout - 2
Method 1: Drawing Polygons in Schematic Layout
Either ... just draw ... Or - import an Artwork Cell
“Dumb” Shapes in Schematic Layout
Select the Library
And drag the cell into the schematic layout
Tip: Make sure you update cell edits!
Layout > Update Cell Edits.
This is ALL drawing layers!
38 Introduction to Layout
Modeling and Drawing Layers
Model Layers Drawing Layers
GDS File Layers
EM Layers
Line Type
Artwork Cell
User Drawn Shape
Parameterized Layout Cell
12
Transistor with associated Artwork Cell
NO SCHEMATIC LINK
Method 2: Associate a Fixed Artwork Cell with a Schematic Element
20
39 Introduction to Layout
Fixed Artwork Cells in Schematic Layout
Schematic View
Schematic Layout View
Artwork Cells
“Dumb” Polygons - no notion of connectivity
Need Cell Ports or Cell Pins
Transistor
Symbol in Schematic
Notion of Connectivity Exists
40 Introduction to Layout
Cell Ports and Cell Pins
Step 8: Add a cell port to our DXF cell.
Cell Edit Toolbar
Cell Port has been added.
21
41 Introduction to Layout
Cell Ports and Cell Pins - 2
Step 9: Add a Cell Pin
Two ways to it:
1. Draw > Cell Pin
2. Draw the rectangle - then
RC > Cell Pin
Note: The arrow shows where the ratsline will attach.
We’ll get into more advanced control options next chapter.
The Cell Pin is placed in the middle of the pad.
Tip: Put the cell pin on AWR_Top_Copper - it’s important that you get the layer right for:
1. It will draw metal!
2. For DRC checking.
42 Introduction to Layout
Cell Ports and Cell Pins - 3
Step 10: Create a new schematic - “Pad Model”.
- Model the transition as as an inductor.
- Associate the inductor with the pad layout.
We are going to give this inductor the layout of the pad.
22
43 Introduction to Layout
Cell Ports and Cell Pins - 4
RIght Click (RC) on the inductor > Properties ... or Double Click.
Go to the Layout Tab of the Properties Window.
44 Introduction to Layout
Cell Ports and Cell Pins - 5
Schematic Layout
The Rats Lines - Connectivity is included.
Cell Port - Rats Line only disappears is aligned exactly.
Cell Pin - Rats line disappears if anywhere in area of pin.
MMIC people like this.
RFIC and Board people like
this.
Snap Together
23
45 Introduction to Layout
Modeling and Drawing Layers
Model Layers Drawing Layers
GDS File Layers
EM Layers
Line Type
Artwork Cell
User Drawn Shape
Parameterized Layout Cell
12
Transistor with associated Artwork Cell
NO SCHEMATIC LINK
PCells and Model Layers
46 Introduction to Layout
PCells
• 2 types of PCells ...
• Type 1: These Look for Certain Model Layers -
– Thin Film Resistors - Metal1, NiCr
– Bondwires - Bondwires Layer
– Thin Film Capacitor - Metal0, Metal1, MIM
– Make sure the model layer mapping is right.
– Note: In supplied PDK’s - they are using Structure Types...
• Type 2: These models use LineTypes in the LPF file.– Transmission Line Models.
– Vias.
• PCells normally come precompiled (C++).
Note: You can write/compile your own PCells ...
- PDK Training course.
24
47 Introduction to Layout
PCells - 2
How MLIN Draws
• The LPF file has LINETYPE defined:
• $LINE_TYPE_BEGIN "Top Line"
• ! -> Layer offset minWidth flags
• “AWR_Top_Copper” 0 50e-005 0
• $LINE_TYPE_END Name of Line type is “Top
Line”
Uses Model Layer
“AWR_Top_Copper”
Shape Properties