ColorZ

“What is the timeline?”

It’s a question the CEO of Marvell, Matt Murphy, would pose to Loi Nguyen each year during their one-on-one meetings. “I’ve always thought of myself as a young guy; retirement seemed far away,” says Nguyen. “Then, in October, it seemed like the time is now.”

Nguyen will not, however, disappear. He will work on specific projects and take part in events, but this will no longer be a full-time role.

Early life and journey to the US

One of nine children, Nguyen grew up in Ho Chi Minh City, Vietnam. Mathematically inclined from an early age, he faced limited options when considering higher education.

“In the 1970s, you could only apply to one university, and you either passed or failed,” he says. “That decided your career.”

Study choices were also limited, either engineering or physics. Nguyen chose physics, believing entrance would be easier.

After just one year at university, he joined the thousands of ‘boat people’ that left Vietnam by sea following the end of the Vietnam War in 1975.

But that one year at university was pivotal. “It proved I could get into a very tough competitive environment,” he says. “I could compete with the best.”

Nguyen arrived in the US with limited English and no money. He found work in his first year before signing up at a community college. Here, he excelled and graduated with first-class honours.

Finding a mentor & purpose

Nguyen’s next achievement was to gain a full scholarship to study at Cornell University. At Cornell, Nguyen planned to earn his degree, find a job, and support his family in Vietnam. Then a Cornell academic changed everything.

The late Professor Lester Eastman was a pioneer researcher in high-speed semiconductor devices and circuits using materials such as gallium arsenide and indium phosphide. “Field-effect transistors (FETs), bipolar – any kind of high-speed devices,” says Nguyen. “I was just so inspired by how he talked about his research.”

In his senior year, Nguyen talked to his classmates about their plans. Most students sought industry jobs, but the best students were advancing to graduate school.

“What is graduate school?” Nguyen asked and was told about gaining a doctorate. “How one does that?” he asked and was told about the US Graduate Record Examination (GRE). “I hadn’t a clue,” he says.

The GRE deadline to apply to top US universities was only a week away, including an exam. Nguyen passed. He could now pursue a doctorate at leading US universities, but he chose to stay at Cornell under Professor Eastman: “I wanted to do high-speed semiconductors.”

His PhD addressed gallium arsenide FETs, which became the basis for today’s satellite communications.

Early career breakthroughs

After graduating, he worked for a satellite company focussing on low-noise amplifiers. NASA used some of the work for a remote sensing satellite to study cosmic microwave background radiation. “We were making what was considered the most sensitive low-noise receivers ever,” says Nguyen.

However, the work concluded in the early 1990s, a period of defence and research budget cuts. “I got bored and wondered what to do next,” he says.

Nguyen’s expertise was in specialised compound semiconductor devices, whereas CMOS was the dominant process technology for chip designs. He decided to undertake an MBA, which led to his co-founding the high-speed communications chip company Inphi.

While studying for his MBA, he met Tim Semones, another Inphi co-founder. The third co-founder was Gopal Raghavan whom Nguyen describes as a classic genius: “The guy could do anything.”

Building Inphi: innovation through persistence

The late 1990s internet boom created the perfect environment for a semiconductor start-up. Nguyen, Semones, and Raghavan raised $12 million to found Inphi, shorthand for indium phosphide.

The company’s first decade was focused on analogue and mixed-signal design. The market used 10-gigabit optics, so Inphi focused on 40 gigabits. But then the whole optical market collapsed, and the company had to repurpose.

Inphi went from designing indium phosphide chips at 40 gigabits-per-second (Gbps) to CMOS process circuits for memory working at 400 megabits-per-second (Mbps).

In 2007, AT&T started to deploy 40Gbps, indicating that the optical market was returning. Nguyen asked the chairman for a small team which subsequently developed components such as trans-impedance amplifiers and drivers. Inphi was too late for 40Gbps, so it focussed on chips for 100Gbps coherent optics.

Inphi also identified the emerging cloud data centre opportunity for optics. Initially, Nguyen considered whether 100Gbps coherent optics could be adopted within the data centre. However, coherent was too fast and costly compared to traditional non-return-to-zero (NRZ) signalling-based optics.

It led to Inphi developing a 4-level pulse-amplitude modulation (PAM4) chip. Nguyen says that, at the time, he didn’t know of PAM4 but understood that Inphi needed to develop technology that supported higher-order modulation schemes.

“We had no customer, so we had to spend our own money to develop the first PAM4 chip,” says Nguyen.

Nguyen also led another Inphi group in developing an in-house silicon photonics design capability.

These two core technologies – silicon photonics and PAM4 – would prove key in Inphi’s fortunes and gain the company a key design win with hyperscaler Microsoft with the COLORZ optical module.

Microsoft met Inphi staff at a show and described wanting a 100Gbps optical module that could operate over 80km to link data centre sites yet would consume under 3.5W. No design had done that before.

Inphi had PAM4 and silicon photonics by then and worked with Microsoft for a year to make it happen. “That’s how innovation happens; give engineers a good problem, and they figure out how to solve it,” says Nguyen.

Marvell transformation

The COVID-19 pandemic created unlikely opportunities. Marvell’s CEO, Matt Murphy, and then-Inphi CEO, Ford Tamer, served on the Semiconductor Industry Association (SIA) board together. It led to them discussing a potential acquisition during hikes in the summer of 2020 when offices were closed. By 2021, Marvell acquired Inphi for $10 billion.

“Matt asked me to stay on to help with the transition,” says Nguyen. “I knew that for the transition to be successful, I could play a key role as an Inphi co-founder.”

Nguyen was promoted to manage most of the Inphi optical portfolio and Marvell’s copper physical layer portfolio.

“Matt runs a much bigger company, and he has very well thought-out measurement processes that he runs throughout the year,” he says. “It is one of those things that I needed to learn: how to do things differently.”

The change as part of Marvell was welcome. “It invigorated me and asked me to take stock of who I am and what skills I bring to the table,” says Nguyen.

AI and connectivity

After helping ensure a successful merger integration, Nguyen returned to his engineering roots, focusing on optical connectivity for AI. By studying how companies like Nvidia, Google, and Amazon architect their networks, he gained insights into future infrastructure needs.

“You can figure out roughly how many layers of switching they will need for this and the ratio between optical interconnect and the GPU, TPU or xPU,” he says. “Those are things that are super useful.”

Nguyen says there are two “buckets” to consider: scale-up and scale-out networks. Scale-out is needed when connecting 10,000s, 100,000 and, in the future, 1 million xPUs via network interface cards. Scale-out networks use protocols such as Infiniband or Ethernet that minimise and handle packet loss.

Scale-up refers to the interconnect between xPUs in a very high bandwidth, low latency network. This more local network allows the xPUs to share each other’s memory. Here, copper is used: it is cheap and reliable. “Everyone loves copper,” says Nguyen. But copper’s limitation is reach, which keeps shrinking as signalling speeds increase.

“At 200 gigabits, if you go outside the rack, optics is needed,” he says. “So next-gen scale-up represents a massive opportunity for optics,” he says.

Nguyen notes that scale-up and scale-out grow in tandem. It was eight xPUs in a scale-up for up to a 25,000 xPU scale-out network cluster. Now, it is 72 xPUs scale-up for a 100,000 xPU cluster. This trend will continue.

Beyond Technology

Nguyen’s passion for wildlife photography is due to his wife. Some 30 years ago, he and his wife supported the reintroduction of wolves to the Yellowstone national Park in the US.

After Inphi’s initial public offering (IPO) in 2010, Nguyen could donate money to defend wildlife, and he and his wife were invited to a VIP retreat there.

“I just fell in love with the place and started taking up photography,” he says. Though initially frustrated by elusive wolves, his characteristic determination took over. “The thing about me is that if I’m into something, I want to be the best at it. I don’t dabble in things,” he says, laughing. “I’m very obsessive about what I want to spend my time on.

He has travelled widely to pursue his passion, taking what have proved to be award-winning photos.

Full Circle: becoming a role model

Perhaps most meaningful in Nguyen’s next chapter is his commitment to Vietnam, where he’s been embraced as a high-tech role model and a national hero.

He plans to encourage young people to pursue engineering careers and develop Vietnam’s high-speed semiconductor industry, completing a circle that began with his departure decades ago.

He also wants to spend time with his wife and family, including going on an African safari.

He won’t miss back-to-back Zoom calls and evenings away from home. In the last two years, he estimates that he has been away from home between 60 and 70 per cent of the time.

It seems retirement isn’t an ending but a new beginning.