Cad Wiki for Analog IC Courses

Closely follow the following steps to setup Cadence for the ECE5/410 class:

• Log into ams1 or ams2 servers using the directions here and open a terminal window.

• Change your ams password by using the command

yppasswd

• Change your directory permissions by using the chmod command. Make sure that others are not able to read your files.

cd ..
chmod  –R  700  <youraccount>
Example: chmod  –R  700  vsaxena

• Copy the .bashrc file from the 5410grader user account, and then source it

cd
cp  ../5410grader/.bashrc  ./
source  .bashrc

Setting up the course directory

• Copy the course directory from the 5410 user account and restrict the permissions

cp  –r  ../5410grader/ece510   ./
chmod  700  ece510

Using Cadence

• Open a terminal window, and then go to the ece510 directory and use “virtuoso &” command to start Cadence.

cd ece510
virtuoso &

Your Cadence environment is already set up to start Cadence IC610 version. You need to start Cadence from ece510 directory for the default setups to work.

• Note that icfb has been replaced with virtuoso in IC610; however, icfb will still start Cadence in the first release of IC610.

To ensure that the CMOS book examples run seamlessly in you work directory, once for all, do the following:

• Log into either of the AMS servers. Goto your home directory:

cd

• If it doesn't exist already, create a symbolic link to the CMOSedu library installation, using the command

ln -s /home/pdks/Cadence_IC61_CMOSedu CMOSedu

• he Spectre models for the OnSemi/AMI C5 0.5µm CMOS process are located at:

/home/pdks/ncsu-cdk-1.6.0.beta/models/spectre/standalone For On Semi C5 process: Select the models ami06N.m and ami06P.m in the ADE window models setup.

• The book models are located in the same directory as the examples. Otherwise you can access them from the location

/home/vsaxena/analog_design/models

Basic instructions for simulating CMOS book examples using Cadence Spectre (refer to the Cadence Tutorials for details):

• With Cadence running, use the Library Manager to open the schematic view of a cell for simulation using Virtuoso Schematic Editor (SE)
• You may not have write permission to run the schematics. You can create a local copy of the library using the Library Manager view and then work on the local copy of the library.
• In the menu of the SE Window select Launch → ADE L to open the Virtuoso Analog Design Environment (ADE) Window. Use the ‘Always’ option when prompted for license.
• In the ADE Window’s menu select Setup → Simulator/Directory/Host… and then set the Simulator menu item
  • For most simulations Spectre will be used, if UltraSim or some other simulator is used it will be noted on the schematic. In your environment, Spectre should already be set up as the default simulator.
• Next, again in the ADE Window’s menu, select Session → Load State
  • set the Load State Option to Cellview and press OK
  • You may have to update the state format by clicking Ok on few widgets as we are using a newer version of Cadence than the examples.
• Finally, in the ADE Window’s menu select Simulation → Netlist and Run (or just hit the green button) to simulate.

• Use the MOSIS Scalable CMOS (SCMOS) SUBM design rules for your ece510 layouts. The design rules can be found in this document. Note that the design rules are given in terms of lambda (=0.3u) while Cadence Virtuoso uses absolute values without any scaling. Thus in your layouts, multiply all design rule numbers by 0.3u for final layout dimensions. Eg. the minimum N-well width of 12 translates into 12*0.3u=3.6u in Virtuoso layout.

• Process information including sheet resistances, capacitances, and transistor parameters can be found here: amiprocess.pdf
• The gate oxide capacitance Cox' is calculated as: Cox'=e0*eox/tox = (8.85 aF/um * 3.97)/14.1e-3 um = 2.5fF/um^2

• Corner models for the C5 process are already available on the AMS server at the location

 /home/pdks/ncsu-cdk-1.6.0.beta/models/spectre/  

* MOSIS information for the C5 0.5u process is available here.