Cadence Tutorial1: Schematic entry and Basic gate drawing

 

  1. Invoke "icfb" program at cds directory. (icfb is a front to back end cadence integration)

%icfb &

ICFB is a cadence tool which is used for library development and encompasses the full chip functionality.

 

CIW

 

 

  1. Create MyLib Library using File Menu on CIW.

File->New->LIbrary

In [New Library] window,

Name: MyLib

Technology File: Don't need tech file

 

Library is defined as a collection of some basic cells like NAND, INVERTER, FLIPFLOP etc. with their properties defined in views like schematic, symbol, functional and layout.

 

 

  1. Open Library Manager using Tools menu in ICFB

Tools -> Library Manager

 

  1. Open Schematic Window using File Menu in Library Manager.

%File->New->Cellview

In [Create New File] window,

Library Name: MyLib

Cell Name: inverter

View Name: schematic

Tool: Composer-Schematic

Click OK

 

  1. Place nmos transistor

sch:Add->Component (or "i")

Add Component : click Browse

In [Library Browser] window,

Library : tsmc25Lib

Cell : nfet3

View : symbol

When you move mouse into schematic window, nfet3 symbol will follow your pointer. Click "mouse L" to place nfet.

Type "Esc" to exit adding component action.

 

Please refer to Chapter1 Section3 of the Cadence Virtuoso composer user guide for understanding the concept of instance.

 

 

 

  1. Place the nfet on the schematic window somewhere and change the size of the nfet by

Click on the nfet and the Edit -> Properties -> Object or by pressing q

Change the width of the nfet to 500n

 

  1. In the same way place a pfet3 from tsmc25Lib and change the size of the pfet3 to 1u.

 

 

  1. In the same way select vdd and gnd symbols from basic library and connect to pfet3 and nfet3 respectively.

 

 

  1. Connect each component using wires.

Place mouse pointer on one of the node you want to connect.

sch: Add->Wire(narrow) (or "w")

Click "mouse Left button", drag to other node to connect, and

click "mouse L button" to finish.

To make wire open node at one end (like input and output of inverter), double-click "mouse L"

 

 

  1. Place pins.

sch:Add->Pin (or "p")

In [Add Pin] window,

Pin Names : A

Direction : input

Move mouse to place A pin at input of inverter, then click "mouse L"

For output pin X: In [Add Pin] window, change direction to output.

Place X pin at output of inverter

 

 

  1. To save the schematic

Design -> Check and Save.

 

Creating symbol for inverter

Please refer to Chapter1 Section5 of the Cadence Virtuoso composer user guide for creating the symbol view

 

  1. Create a symbol view from Library Manager in the same way schematic view was created

 

 

  1. Draw outline for inverter symbol.

Click line icon on left toolbox of symbol window and draw outline of inverter.

 

  1. Finish outline of inverter by adding circle.

Add->Shape->Circle

 

 

  1. Place pins.

sym:Add->Pin (or "p")

In [Add Pin] window,

Pin Names : A

Direction : input

Type : square

Move mouse to place A pin at input of inverter, then click "mouse L".

In [Add Pin] window, change direction to output for pin X.

Place X pin at output of inverter.

 

  1. Add labels.

sym:Add->Label

In [Add Pin] window,

Label : [@instanceName]

Place instanceName label

Comment: Instance name label is the name of the instances used in the schematic. The value of the instanceName will be assigned automatically in the top schematic.

 

 

  1. Check and Save

sym:File->Check and Save

 

 

For more help please refer to Virtuoso Schematic Composer user guide using CDSDOC.

 

In case of any bug or comment please email to pgolani@usc.edu or pabeerel@usc.edu