SiFive. SiFive, Inc. is an American fabless semiconductor company and provider of commercial RISC-V processors and silicon chips based on the RISC-V instruction set architecture (ISA). Its products include cores, SoCs, IPs, and development boards.

SiFive is one of the first companies to produce a chip that implements the RISC-V ISA.

History 
In 2015, researchers Krste Asanović, Yunsup Lee, and Andrew Waterman from the University of California Berkeley founded SiFive. On November 29, 2016, SiFive released the Freedom Everywhere 310 SoC and the HiFive development board. This made it the first company to produce a chip that implements the RISC-V ISA since universities had already produced RISC-V processors.

Naveed Sherwani was appointed as the CEO in August 2017. In October the same year, SiFive did a limited release of its U54-MC, which was reported to be the first RISC-V based 64-bit quad-core CPU that supported comprehensive operating systems like Linux.

In June 2018, SiFive acquired Open-Silicon for an undisclosed amount and retained their application-specific integrated circuit (ASIC) design capabilities.

In February 2018, SiFive released the HiFive Unleashed, a development board containing a 64-bit SoC with four U54 cores.

In September 2020, Patrick Little was appointed as the CEO.

In October 2020, SiFive released the HiFive Unmatched, a Mini-ITX development board with four U74-MC cores, one S7 core, 8GB DDR4 RAM, four USB 3.2 Gen1 ports, one PCI Express x16 slot, one PCIe Gen3 x4, one microSD card slot, and a Gigabit Ethernet. In April 2021, the company also taped out its first system-on-chip on TSMC's N5 process technology, making it the first RISC-V-based device to be made using a 5 nm node.

In June 2021, Canonical announced its Ubuntu operating system supports the HiFive Unmatched and HiFive Unleashed, and the Barcelona Supercomputing Center collaborated with Codeplay Software and SiFive to implement support for the RISC-V V-extension v0.10 in the LLVM compilation infrastructure, providing vector computation capabilities through C/C++ intrinsics. Reports of a potential buyout of SiFive by Intel and other companies emerged, however Intel's plans were eventually cancelled due to disagreements with SiFive.

In 2023, it was reported that SiFive had laid off 20% of its staff.

SiFive became the main sponsor of the Cambridge United F.C. for the 2022/23 and the 2023/24 seasons. The partnership is intended to amplify both of their visions to support each other and the community, as well as establish SiFive within the city.

Growth 
In September 2015, SiFive raised $5 million in Series A funding. In May 2017 SiFive raised $8.5 million in Series B.

In April 2018, SiFive received $50.6 million Series C funding, including a major amount from Intel Capital.

In June 2019, SiFive received $65.4 million in a Series D funding round led by existing investors Sutter Hill Ventures, Chengwei Capital, Spark Capital, Osage University Partners and Huami, alongside new investor Qualcomm Ventures. This brought the total investment in SiFive to $125 million.

On October 23, 2019, at the Linley Fall Processor Conference, SiFive announced the release of SiFive Shield, a platform security architecture. In December 2019, the company announced the SiFive Apex cores for mission-critical markets and SiFive Intelligence cores for vector processing workloads. Later that month, Samsung also announced it will be using SiFive RISC-V cores for SoCs, automotive, and 5G applications.

In January 2020, SiFive hired Chris Lattner, an American software engineer best known as the main author of LLVM and related projects such as the Clang compiler and the Swift programming language. He joined SiFive as Senior Vice President of Platform Engineering after two years at Google.

In August 2020, SiFive received $60 million in a Series E funding round led by investors SK Hynix and Saudi Aramco. This brought the total investment in SiFive to $186 million. That same month, SiFive announced the creation of the OpenFive business unit to focus on the creation of processor-agnostic custom SoC design.

Chip company Tenstorrent, headed by former top AMD engineers, including CTO Jim Keller, licensed SiFive's Intelligence X280 processor cores in October 2020 into its homegrown AI training and inference chips. Renesas Electronics also announced partnering with SiFive to design chips for vehicles.

In June 2021, SiFive launched a new processor family with two core designs: P270, a Linux-capable CPU; and P550, the highest-performing RISC-V CPU. At the same time, Intel's Foundry Service adopted P550 for use in its Horse Creek platform, a RISC-V development platform built on Intel's newest 7 nm process node, Intel 4. The announcement furthered speculation of a potential acquisition of SiFive by Intel, which reportedly offered to acquire SiFive for $2 billion.

As part of SiFive's “relentless innovation” program, the company announced SiFive 21G2 update for the SiFive Essential family including 11% faster U74 cores.

In March 2022, SiFive received $175 million in a Series F funding round led by Coatue Management, valuing the company at over $2.5 billion. This brought the total investment in SiFive to over $350 million.

In October 2023, SiFive laid off approximately 20% (~140) of its 650 employees. SiFive reiterated their commitment to existing products and lines and stated that the company is "well funded for years in the future and continue to work".

Products 

 RISC-V cores: SiFive core series – The SiFive core IPs  consists of three distinct families spanning from high-performance application processors to area-optimized, low-power embedded 64- and 32-bit microcontrollers, to vector processors. All SiFive processors are based upon the RISC-V ISA.
The SiFive Performance processor family are designed for higher throughput and performance.
The SiFive Intelligence family uses a software approach to processor design to address the future requirements of deploying machine learning technology to accelerate AI/ML applications.
The SiFive Essential family of processor cores spans from high-performance multi-core heterogeneous application processors to area-optimized, low-power embedded microcontrollers. SiFive Essential standard core microarchitectures are based on the RISC-V ISA to provide 64-bit and 32-bit options and can be configured using SiFive Core Designer to create custom configurations. 
 SoC IP – The SoC IP is customizable, or customers choose from memory interface IP, connectivity IP, or system and peripheral IP.
 Custom SoC – Starting with an SoC template, users can create custom SoC designs to be optimized for power, performance, and area.
 Boards and software – SiFive also produces the FE310 microcontroller, HiFive1, HiFive Unleashed, and other development boards and software.

DesignShare platform 
DesignShare was an open source platform for building prototypes. SiFive partnered with vendors to provide IP to customers designing custom chip prototypes without paying IP fees in advance. Once chip designs were ready for mass production, customers would pay for the IP. DesignShare partners included Brite Semiconductor, Rambus, Chipus Microelectronics, and more.

References 

Fabless semiconductor companies
Semiconductor companies of the United States
Open hardware organizations and companies
Open microprocessors
American companies established in 2015
Companies based in Santa Clara, California
2015 establishments in California