IC studio - SPICE/Symbol Tutorial

From ift

Include a SPICE File in IC Studio

This is a description of how to download a spice file from the web and include it in your IC studio project. A symbol is created to represent the component described by the spice file, and the procedure of linking the spice file to your symbol is described (See the IC studio tutorial if you are new to symbols). The AD8000 opamp is used as an example throughout this tutorial.

Download a SPICE File

Search the internet for a spice model, i.e. "AD8000 spice model". The vendor will normally provide such a file which can be downloaded. Open the file (ad8000p.cir) in a text editor and scroll down to the node assignments. The node assignments should match (identically) the pins of your soon to be created symbol.

 * Node assignments
 *                non-inverting input
 *                | inverting input
 *                | | positive supply
 *                | | |  negative supply
 *                | | |  |    output
 *                | | |  |    |     Power down
 *                | | |  |    |     |
 .SUBCKT AD8000   1 2 Vcc Vee Vout  PD

Create a Symbol

First you have to create a project library as explained in IC studio. In the cell view you should create a cell for your component which is of the view type "symbol". The next step is to start drawing your symbol with the desired shape and pins:

Use the palette on the left side of the screen to draw lines, or use a predefined shape (i.e. a rectangle). From the same palette you can choose the "Add Pin" button. Choose the pin preferences as you find suitable, but note that the pin names must be identical to the node assignments in the spice file. Place your pins and create a nice symbol...

Relate a SPICE File to a Symbol

Now you have a symbol, but it does not have any relation to the spice file except from the pin names. Right click on the cell you just made and add a new view of the type "spice". An almost blank spice file will pop up in the IC Studio text editor. Delete what is there and go to "file->insert file" and choose the spice file you have downloaded (you can also copy-paste the spice file) - save it.

When you close the text editor, you will get a message: "Spice File Changed - Do you want to change the top sub-circuit"? Press yes and select the desired sub-circuit name. The following message should appear in IC Studio:

 //  Starting Spice registration ... please wait
 //  Note: Registering SPICE model "AD8000" with symbol "ad8000"
 //  Note: Registration succeeded

Create a new cell with your top-level circuit ("schematic" view). Now you can include the component by "Right-click -> Instance -> Choose Symbol -> Your symbol" and draw your circuit around it.

That's it!

Doesn't Work?

  • Did you "Create Viewpoint" as described in IC studio?
  • Did you "Set Simulation Models" as described in IC studio?
  • Did you choose an "Analysis" (i.e. "Transient" or "DC") to be performed in simulation mode?
  • Do the node assignments correspond to the pin names on your symbol?
  • Some spice models you find on the web are written for PSPICE, HSPICE or some other SPICE language that might have syntax which is not supported by ELDO. Try to comment these out within the SPICE file, or replace with supported syntax (see ELDO User's Manual).