EE4321-VLSI CIRCUITS : HSPICE and AWAVES Information

EE E4321 - VLSI CIRCUITS

HSPICE and AWAVES Information

If you haven't read the CAD tool information page, READ THAT FIRST.

SPICE is a general purpose circuit simulation program. We will use HSPICE , a commercial version of SPICE for all our circuit simulation requirements.

In our VLSI lab environment, you can do circuit simulation in two ways :

1) Using HSPICE in batch mode.
2) Using HSPICE from the analog artist environment of Cadence' ICFB set of tools.

This page emphasizes HSPICE in batch mode only. It consists of two parts. Part I describes the procedure while Part II walks you through examples based on Part I.

PART I

1.The first step is to create a SPICE input file. An input file for hspice is a text file which contains the description of the circuit in SPICE syntax as well as information regarding the analysis of the circuit. You must have written such a file describing your circuit before you can run hspice. Check the "miscellaneous links" section of the course webpage and follow the link "overview of circuit simulator SPICE" if you don't know how to describe your circuit in SPICE syntax.

Its a good idea to give an extension of .sp or .spi to the SPICE input file which is also called a "netlist".

2. Now Type the following command at the command prompt :

$ hspice

It will prompt you for an input file name. Give the file name of the SPICE netlist that you created in Step 1. It prompts you for a few more questions which are self explanatory but even hitting "Return" on all of them will be fine.

HSPICE runs in background and after some delay(simulation time based on your circuit complexity), you get either a HSPICE job concluded or HSPICE job aborted message.

If you get an "aborted" message, open the output file (generally with extension .lis unless you specified a different output file name while answering the several prompts) and scroll down to look for any errors. If you are unable to understand/fix the error either refer to the SPICE tutorial or contact the TA/Instructor.

If you get a "concluded" message, your simulation was successful and you are ready to view the results.

3. You view the plots using a graph viewing tool called AvanWaves. Type awaves at the command prompt to invoke AvanWaves. If your display settings are correct, you will soon see the GUI of awaves popping up on your screen. A result browser window of AvanWaves also pops up at the same time. Choose the design by clicking on it in the result browser. Now click on voltages/current to plot to see the required plots.

PART II

Follow the instructions :

you are going to run hspice on an example circuit from the HSPICE user manual. To open the manual, type the following on command prompt :

$ acroread /usr/cad/meta/2000.4/docs/hspice_manual/pdf/hspice.pdf &

Acrobat reader opens the HSPICE user manual pdf file.
Go to Chapter 2 - Getting Started
CVN students can download chapter 2 from here .
Go to page 2-2 and copy the SPICE netlist given here in a text file of yours. Understand each and every statement.
Note that the first statement in the netlist is always a comment and is not read by the compiler. Always use the first line to give a title to your circuit.
Also Note that you have to specify "post" in .options statement in order to produce data in a form readable by AvanWaves. If it is missing, you will not be able to view the database in awaves even though your simulation was successful.
Follow steps 1 to 4 on page 2-3.
(Note in Step 2 , another recommended style of invoking hspice.)
In step 4, run AvanWaves as described in Part I above.
Plot the curve shown in Fig 2.2.
Similarly do the rest of the two examples.

As a last exercise, you will make some changes in the third example to fit it to TSMC 0.25u, the technology that we will use in our course for all assignments and projects.
Make the following changes in your SPICE netlist for the third example of "transient analysis of an inverter".

Change VCC VCC 0 5 to VCC VCC 0 2.5
Delete the two lines starting with .MODEL
Insert following line after the .PRINT statement :
.INCLUDE /usr/tech/tsmc025/models/tsmctt
Save and quit . Now again run this modified example 3 in HSPICE and plot the same curves as in fig 2-5.

You are highly encouraged to read relevant sections of the HSPICE and AvanWaves user manuals. The locations are :

/usr/cad/meta/2000.4/docs/hspice_manual/pdf/hspice.pdf for HSPICE.
/usr/cad/meta/2000.4/docs/awaves_manual/pdf/avanwaves.pdf for Awaves.
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