introduction to the layout environmentecee.colorado.edu/~ecen4634/6_intro_layout.pdfintroduction to...

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


Modeling and Drawing Layers

Model Layers Drawing Layers

GDS File Layers

EM Layers

Line Type

Artwork Cell

User Drawn Shape

Parameterized Layout Cell

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Transistor with associated Artwork Cell

NO SCHEMATIC LINK

We need to understand how this works


Drawing Layers


GDS File Layers

EM Layers

Line Type

Artwork Cell

User Drawn Shape


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NO SCHEMATIC LINK

Start with Drawing Layers

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Drawing Layers - 2

Drawing Layers

The rule is: If you “see” it - it’s a drawing layer.

Schematic Layout View Artwork Cells

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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)


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


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


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

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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


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

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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


Using Drawing Layers - 2

Schematic View


Circuit

Artwork Cells


- including connectivity (ratslines)


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


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.


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.

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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


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!

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Tip: Cloak the

System Layers

MWO has

certain

system

layers it

needs

But keep them Visible!



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)

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Drawn First

Drawn Last

Tip: solid layer might hide other layers

Drawn FirstDrawn First

Not Solid

Solid

Very important for

Negative Layers.


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?

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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


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


Modeling Layers


GDS File Layers

EM Layers

Line Type

Artwork Cell

User Drawn Shape


12


NO SCHEMATIC LINK

Modeling Layers


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 ...

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Simple Approach - Use One Set of Layer Definitions

Schematic

Artwork Cells

Final LayoutExternal

World


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

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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 ...


Import of GDSII and DXF

Schematic View


Circuit

Artwork Cells


- includingconnectivity (ratslines)


External World

•GDSII

•DXF

Need Cell Faces or Cell PinsWe are down here!

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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


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.

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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.


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

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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


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

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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.


MWO Layout

Schematic View


Circuit

Artwork Cells


- includingconnectivity (ratslines)


External World

•GDSII

•DXF

Need Cell Faces or Cell Pins

External World

Need Export Mapping

We are here!

19


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!




GDS File Layers

EM Layers

Line Type

Artwork Cell

User Drawn Shape


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NO SCHEMATIC LINK

Method 2: Associate a Fixed Artwork Cell with a Schematic Element

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Fixed Artwork Cells in Schematic Layout

Schematic View


Artwork Cells


Need Cell Ports or Cell Pins

Transistor

Symbol in Schematic

Notion of Connectivity Exists


Cell Ports and Cell Pins

Step 8: Add a cell port to our DXF cell.

Cell Edit Toolbar

Cell Port has been added.

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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.



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.

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RIght Click (RC) on the inductor > Properties ... or Double Click.

Go to the Layout Tab of the Properties Window.



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

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GDS File Layers

EM Layers

Line Type

Artwork Cell

User Drawn Shape


12


NO SCHEMATIC LINK

PCells and Model Layers


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.

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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

introduction to the layout environmentecee.colorado.edu/~ecen4634/6_intro_layout.pdfintroduction to...

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