Introduction

What is Cadence Virtuoso?

Cadence Virtuoso is a powerful industry grade IC simulator that can simulate semiconductor devices to a very low level and a very high degree of accuracy. It is so powerful that it usually requires external servers to run, which we will be accessing.

What is a PDK?

A PDK (Process Design Kit) is a set of files with the specifications for a specific technology (manufacturing process for semiconductors). PDKs include the performance characteristics of the different types of transistors in their specific ICs. PDKs are mostly made by IC manufacturers and distributed to IC designers, with the purpose being that IC designers can use the PDK to simulate the performance characteristics of the chips they design at the specific technology (manufacturing process). However, these PDKs contain detailed specs about the performance of giant corporations products, and as such semiconductor manufacturers are not super keen to go giving them out. And even if you somehow were able to get a company to grant you access to their PDK, it would be under serious NDAs, which hinder the collaborative dissemination of knowledge that is so often our goal in academia.

NCSU’s FreePDK45

Luckily, some of the great people at North Carolina State University designed a PDK that anyone can use for educational purposes for free, sharing it as they like. There are multiple PDKs they created as a part of the FreePDK project, but the one this tutorial will be using is FreePDK45. FreePDK45 is a predictive technology model, which means it doesn’t represent any specific process, but is more of an aggregation of the general performance characteristics of 45 nanometer technology levels.

1: Gain Access to Cadence Virtuoso on the RPI ECSE Servers

Go through the first part of Basic Cadence, IC design for beginners recreated below

Thanks to @Mary Hueston for putting this together.

Remote Desktop Protocol Connection

In order to access Cadence, you have to connect to an RDP (Remote Desktop Protocol) client using an RPI Teaching Server. Below are the options for doing so:

• Windows: The app Remote Desktop Connection should come pre-installed. This is a good default, although sometimes the resolution will not work correctly, resulting in extremely small text. In this case, try the app mRemoteNG (download here: https://mremoteng.org/download)
• Mac OSX: An RDP does not come pre-installed, but you can find a Microsoft Remote Desktop client via the Apple Store.
• Linux OS: The app Remmina is a good RDP option.

Once you have your RDP installed, you are ready to connect to the RPI Teaching Servers.

NOTE: In order to connect to the Teaching Servers, you need to be on RPI WiFi. If you are physically off-campus, you can find instructions for connecting to a VPN here: https://itssc.rpi.edu/hc/en-us/articles/360008783172-VPN-Installation-and-Connection

This article will use the Windows Remote Desktop Connection app for clarity.

Opening Remote Desktop Connection, you should see the screen below. Enter the name of the server you wish to connect to in the box labeled “Computer” and your username (typically your RCS ID, the part before your email) in the box labeled “User name.”(Note that you may need to press “show options” to fill in your username)

RPI has three different Teaching Servers, all in the format ts[number].ecse.rpi.edu. Information about the specific servers can be found here: https://wiki.ecse.rpi.edu/servers/teaching

This article will use ts3.ecse.rpi.edu, but each server has a maximum capacity of people who can join. If the server you try is full, try a different server.

Once you enter your information, your screen should look something like this:

To simplify the login process, you can uncheck the box that says “Always ask for credentials” below your username. This will allow the RDP to remember your login information.

You can hit “Connect” at the bottom of the screen to connect immediately, but you may wish to adjust the Display settings first. To do this, click on the “Display” tab near the top of the screen. You should see something like this:

Make sure under the “Display configuration” section, the dimensions match the resolution of your screen (look for the “Display Resolution” setting in your device’s Settings app to see your device’s resolution and adjust it if necessary). Smaller resolutions will result in larger font but may be a bit pixelated.

Under the “Colors” section, you can adjust the color quality of the connection. The 32 bit connection (Highest Quality) can cause a slower connection on many devices, so 16 bit or 24 bit is recommended.

NOTE: If you have not yet activated your account you will not be able to access the remote desktop server. You may log in but be prompted with a black or blue screen and no way to interact with the server. To activate your account send an email to [email protected], the system administrator as of 2025. Tell him why you need access the server whether it be for learning purposes or a project your working on. Activating your account will fix this problem.

Once the settings match your desired experience, you can now click the “Connect” button at the bottom of the screen. It should open up to the screen below:

2: Download FreePDK45

click this link https://labs.ece.ncsu.edu/eda/downloads/register

where prompted, enter your RPI Email

You will get an email from NCSU EDA, copy that link into the Firefox browser on the remote desktop

*note that this link will be time limited, you have a good while but if you try to do this again after a year you will need to rerequest a download by putting your email in again.