Virtuoso Layout Editor (VLE) Overview


Zooming In and Out

Selecting shapes

Drawing shapes – Draw nmos and pmos devices

Editing shapes

Placing an instance

Creating pins

Editing the properties of objects

Using path stitching


1.    Opening a layout and review commands


cd layout

layoutPlus & (calls up the Cadence tools)


In the CIW, select File—Open, then enter the following values in the form:

Library Name design

Cell Name pk44chip

View Name layout


The Following are basic editing commands that can be accessed from the pull down menus or your bindkeys.

·         Options > Display =    e” The Options form allows you change your layout environment

                                                              i.      Select the Axis to be on

                                                             ii.      Snap Mode change to orthogonal for Create and Edit

·         Pan =                                  Tab>LMB

·         Zoom In =                          z

·         Zoom in by 2 =                   ^z” also RMB then window area

·         Zoom Out =                        Z

·         Select =                            a” to select 1 item

·         Select = hold                       a” to select more that one item

·         Area Select =                      a” > LMB to window area

·         Deselect =                         ^d

·         Fit View =                          f

·         Redraw=                             ^r

·         Create Rectangle =               r

·         Create Path =                     p” Can do Path stitching the lets you place contacts or vias according to what layer you need to jump up/down to.

·         Stretch =                           s” use F4 to Partial Select to stretch a polygon side

·         Copy =                               c

·         Move =                               m

·         Create Ruler =                    k

·         Delete Ruler =                           K

·         Placing an Instance =           I

·         Edit>Properties  =                 q

·         Create Pins =                       ^p

·         Create contact=                  c

·         View Stop Level 0 =             ^f

·         View Stop Level All =            F

·         Layer Tap =                         t” shows you what layer it taped by highlighting that layer in the LSW.

·         ESC gets you out of a command you will us this often

·         F4 Toggles between Full Select and Partial Select (In banner see Select)

·         LSW = Layer Select Window

·         Turns on/off Viewable and Selectable for Layers, Instances and Pins


2.    Creating an nmos device



Or Tools>Library Manager

Library Name design

Cell Name nmos

View Name layout


Using the following Design Rules to create the nmos device by using the commands above

Design Rules: nmos

1.  ndiff overlap of contact 0.9u

2.  contact minimum width 0.6u

3.  contact spacing 0.6u

4.  contact to gate spacing 0.6u

5.  poly extension 0.6

6.   metal overlap of contact 0.4u


GATE: width 3.6 length 0.6

·         Design > Save nmos


3.    Creating a pmos divice


Or Tools>Library Manager

Library Name design

Cell Name pmos

View Name layout

Design Rules: pmos

1.  nwell overlap of pdiff 0.4u

2.  pdiff overlap of contact 0.9u

3.  contact minimum width 0.6u

4.  contact spacing 0.6u

5.  contact to gate spacing 0.6u

6.  poly extension 0.6u

7.  metal overlap of contact 0.4u


GATE: width 7.2 length 1.0


·         You can start from scratch or copy nmos cell into your pmos cell.

·         Change ndiff to pdiff – Select ndiff Edit>Properties  = ”q

·         Using Edit > Properties continue with the poly length.

·         Use stretch, move and copy to match device width and length and meet design riles.

·         To create nwell, select pdiff – Create > Layer Generation – pdiff grow by 0.4 = nwell dg

·         Design > Save pmos


  1. Editing the Contact Definition in the Technology File


We will need to change the enclosure of pdiff around contact to 0.5 micron,

and the metal1 enclosure around contact to be 0.4 micron.


Do the following to correct the pdif enclosure of contact:


SymContactDevice( (name viaLayer viaPurpose layer1 purpose1 layer2 purpose2 w l (row column xPitch yPitch xBias yBias) encByLayer1 encByLayer2 legalRegion)

Note: A PTAP contact contains the contact layer enclosed by two layers: pdiff and metal1.


Loading the Edited Technology File



5.    Creating an Inverter with the nmos and pmos devices already created.


Library Name design

Cell Name inverter

View Name layout


1.  Cell height 18.0u

2.  Width power and ground 1.8u

3.  ndiff to pdiff spacing 0.5u

4.  metal1 to metal1 spacing 0.8u

5.  metal1 width 0.8u

·         pwr and gnd rail of 1.8u wide with the cell height of 18.0u is already placed.

·         Using “i” instance to Place nmos and pmos devices


Create Instance form appears. Fill in with the following:

Library Design

Cell nmos or pmos

View layout


·         Place device according to the design rules.

·         Add the PTAP/NTAP using the Create contact “c

·         Design Save inverter (keep open)


6.    Creating Pins


There are pins on the schematic for the input (A), output (Y), power (vdd) and

ground (gnd). The corresponding pins must be placed in the layout in order

to add the connectivity to run Virtuoso® Custom Router, Assura™ Verification or Diva® LVS, Virtuoso®-XL layout editor, and layout synthesis tools.


Fill out form like form below:


·         In LSW select Poly pn, Pin A will be on Poly

·         Pin Y gnd and vdd will be on metal1

·         The Pin rectangle must be enclosed by the layer it is placed on.

·         Design Save inverter


7.    Creating the control Block



Library Name design

Cell Name control

View Name layout


Then open the corresponding schematic named control schematic.

The inverter is what you have created, the nand has already been created. Using the commands you used previously place these instances and route the nest.

Try using Path to do Path Stitching.

You will also have to add pins to this level.




Congratulations you have created you first layout!