Open Source PHY

The ubiquity of open-source adoption is a current defining difference between hardware and software. The software industry’s embrace of open-source projects fundamentally democratizes software knowledge and eliminates competitive barriers. While the hardware industry has started to adopt open-source projects (like the Open Compute Project), this embrace has primarily been limited to board-level designs and to publicizing standards. Even more, there are very few “full-stack” open-source projects in the silicon space due to the challenges presented by silicon design. We aim to overcome these challenges and create an open source PHY (high-speed link) in order to demonstrate that open-source mixed signal IC designs are possible.

In software, the cornerstones of Open-Source Software are free distribution, reusability and visibility. For an open source PHY to achieve the spirit of these cornerstones, the PHY needs to be portable between technology nodes, easy to reproduce with industry standard tools, and fundamentally trivial to share publicly on an internet repository like GitHub.

On our path to accomplish these three goals, we designed, taped out, and tested a fully synthesizable, PnR-able, “GitHub-able” high-speed link analog frontend. The frontend is composed of 16 stochastic time-interleaved time-to-digital converters (TDCs) and four phase interpolators.

You can read more about this frontend in our published work.

On the backend of the link, we’ve designed and tape-out a novel digital equalization scheme that uses error detection and error correction to replace the need for custom digital hardware like a decision feedback equalizer (DFE).

Both the frontend and the backend employ open-source frameworks and tools, such as fault and DaVE, in verification, validation and testing. You can find and participate in our project here at our GitHub repository .