Successful silicon of open-source RISC-V microcontroller

17th June 2019

Alex Lynn

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Analog/mixed-signal and specialty foundry, X-FAB Silicon Foundries, together with crowd-sourcing IC platform partner Efabless Corporation, have announced the successful first-silicon availability of the Efabless RISC-V System on Chip (SoC) reference design. This open-source semiconductor project went from design start to tape-out in less than three months using the Efabless design flow based on open-source tools.

The mixed-signal SoC, called Raven, is based on the community developed ultra-low power PicoRV32 RISC-V core. Efabless has successfully bench-tested the Raven at 100MHz, and based on simulations the design should be able to operate at up to 150MHz.

For Raven the open-source top-level design utilises X-FAB proprietary analog IP and is created with an open-source design flow. This hybrid open-source design brings the power of open innovation and at the same time protecting significant investment in proprietary IP.

Efabless and X-FAB chose to manufacture the Raven on X-FAB’s high-reliability XH018 process. This is a flexible 180nm six-metal process with a wide variety of options including a low power option, on-chip isolation for high voltages, and high-temperature flash memory. X-FAB’s XH018 process meets automotive quality requirements and is popular in a wide range of automotive, industrial and medical applications.

The semiconductor design is fully functional and Efabless is now engaged with its initial customers on design of derivative offerings. To the Efabless community Raven is available from the Efabless marketplace as a reference design without license fee consequentially advancing the Efabless open innovation model of community design.

"The successful partnership with Efabless demonstrates X-FAB’s continued commitment to open-source semiconductor development," said Ulrich Bretthauer, Product Marketing Manager at X-FAB. "Nearly 75% of Raven's die area is covered by X-FAB standard library blocks and macros. Using these proven IP blocks increased the reliability of the Raven while minimising first-silicon risk."

Mohamed Kassem, Efabless co-founder and CTO, added: "This project would not have been possible without the support of X-FAB. They have been an early adopter of the Efabless open-innovation model and this project is the logical extension of our collaboration.”

For companies that want to learn how to get started with open-source IP semiconductor design, X-FAB provides a series of free webinars including ‘Handling of Complex & Diverse IC Designs Made Easier’, ‘Design Robustness’, and ‘IC Lifetime Calculation Made Easy’. Design kits and PDKs for open source IP designs are available.