Executive Interview: Liam Devlin, CEO, Plextek RF Integration

Liam Devlin graduated from Leeds University, UK in 1988. He was employed by Philips Research Laboratories, followed by Marconi Caswell where, as Chief Designer, he designed GaAs ICs for both the commercial product line and for customer specific applications. Whilst at Plextek he has led the design and development of over 70 full custom ICs on a range of GaAs and Si processes at frequencies up to 90 GHz. He has also led programmes to develop microwave and mm-wave modules and sub-systems using a variety of technologies.

MWJ –Plextek RF Integration is a UK based design house. Briefly outline its history.

LD–I joined Plextek Ltd in 1996 with the aim of developing an RF and microwave IC design capability to complement Plextek’s already successful communication technology consultancy business. I was originally the only member of the RF IC design team but we started to provide design and consultancy services and in parallel I recruited additional engineers to grow the team.

As time progressed we became involved in larger projects and were able to justify setting up our own RFOW test facility. At the end of 2012 Plextek Ltd restructured its business, separating out a number of distinct lines of business including Plextek RFI, which was formed from the RF and microwave IC design team.

MWJ –What areas of design does the company specialise in?

LD– We specialise in the design and development of RFICs, MMICs and microwave/mm-wave modules. We have designed over 70 custom ICs at frequencies ranging from baseband to 100 GHz and are a third party design house for GCS, TriQuint and WIN. We are also currently finalising an agreement to become a European design partner for Cree. We use a wide range of semiconductor technologies and are seeing significant growth in demand for GaN and we expect the agreement with Cree to expand this area of our business still further.

Our designs are used in a wide range of applications from test instrumentation and defence applications to infrastructure equipment and very high volume consumer wireless devices. We have in-house test facilities for both bare die (RFOW) and SMT packaged components and are able to offer our clients full support with the complete route to market.

Our design services also include the ability to undertake RF system level simulations where the impact of the design using a specific communications protocol is assessed. For example, we can undertake simulations of EVM and spectral leakage for a PA design for multi-level modulation schemes such as QAM 256 and OFDM or perform bit error rate simulations for a full communications receiver.

MWJ –What advantages do you think the separation has brought to the company?

LD–For Plextek RFI the separation allowed us to fully concentrate on the key areas of technology where we excel. Our business offering is technology focused and having our own marketing strategy and website (www.plextekrfi.com) has allowed us to present a clear picture of our capabilities. This is even truer for those lines of business that are more product focussed, for instance Blighter Surveillance Systems.

MWJ –Your microwave and mm-wave module development activity covers a wide range of activities. Please outline what these are?

LD–Our capabilities cover a broad spectrum of technologies including conventional SMT on laminate substrates, High Density Interconnect (HDI), chip and wire, thin film, thick film and LTCC. We work with our clients to select the most appropriate technology to best address their goals. We have developed modules such as mm-wave transceivers, broadband dual channel ESM receivers and high power, fast switching, solid state PAs.

MWJ –How does the company identify the technology sectors it invests in and where do you see growth in the near future?

LD–Although we provide design services using a wide range of RF and microwave technologies, we do not manufacture products ourselves. This means we’re able to select the most appropriate technology options for our clients. It’s important that we’re aware of both the most recent commercially available technologies and enhancements and new technologies in development. We do this by attending key events such as the IMS and European Microwave Week as well as through media articles and conference journals.

MWJ –You mentioned that Plextek RF Integration is a third party design house for GCS, TriQuint and WIN? How important is it for a company such as yours to have relationships with these leading companies?

LD–It has been a benefit both to us and to the foundries. GCS and WIN are pure play foundries and so it’s useful for them to have a design house they can trust where they can refer potential customers who also require a design service. This means we get the design contract and the foundry gets the resulting fabrication. TriQuint has an excellent design team of its own but this team is normally busy designing TriQuint products so there is still a requirement for third party design teams to support its foundry customers.

MWJ –What are the advantages of being an independent design house?

LD–We can pick the technology that is best suited to the requirement. If you were to take a product requirement to a company with a captive foundry it would offer a solution that used one of the processes offered by that foundry. We are able to select from a wide range of solid-state processes and foundries as well as packaging, substrate and PCB processes.

MWJ –One of the most important resources of the company must be its designers. How easy is it to recruit and retain the right calibre of designerand doesthe company invest in their academic and career development?

LD –You’re absolutely right, the quality and experience of our design team is key. It is very difficult to recruit engineers with appropriate design skills. We need designers who can work with a range of technologies drawing on the most appropriate for any specific requirement. When we look to recruit I value personal recommendation highly and always seek to speak with former colleagues. We tend not to recruit graduates without industrial experience as we’re selling design expertise and appropriate experience is vital.

In terms of career development I feel that is just as important to work at retaining existing staff as it is at recruiting new staff. You need to make sure that they are motivated and feel valued. Skilled engineers like challenges and variety, and this is something that we can offer.

MWJ –In the conclusion to the Cover Story you wrote for the February 2014 issue of Microwave Journal – The Future of Mm-wave Packaging– you identified ICs with integrated array antennas and the flip-chip mounted ICs in WLCSP as likely to see commercial deployment. Please elaborate?

LD–At high mm-wave frequencies the amount of series inductance that can be tolerated is tiny. The inductance in the connection between IC pad and package port must be minimized. All of the candidate technologies I discuss in the article have the potential to allow this but what sets these two apart is how well suited they are to low cost high volume production.

The integrated antenna approach has the advantages of combining the power from multiple transmit amplifiers and of allowing beam steering. However, the transmit power is still limited and the incorporation of additional RF filtering is not practical. I think it will succeed for high volume, short range applications such as 802.11ad WLAN.

The WLCSP approach allows less highly integrated components to be packaged. It offers a route to pushing up the operating frequency of current SMT building block components. WLCSP parts still have mm-wave ports that interface to a PCB or motherboard and careful co-design of the WLCSP part and the PCB will be required to achieve optimum performance.

MWJ –Accounts of the death of GaAs may be greatly exaggerated and the evolution of Silicon overhyped. In the sectors of technology that you work in how do you see these technologies competing and developing commercially?

LD–GaAs technology is not in imminent danger of demise but it is being pressed by innovative development work in Si and also by GaN technology. I think that Si solutions are well suited to applications that benefit from high levels of integration and have high production volumes over which the development costs can be amortized. GaAs technologies do still have certain performance benefits and the majority of microwave building block ICs are still realized in GaAs.

GaN was originally considered as a means of developing high power solid state PAs that could displace tube devices. Whilst it is certainly doing this there is also a lot of interest in using GaN for lower cost applications such as cellular base station PAs and even CATV amplifiers. The pace at which semiconductor technologies develop never ceases to impress me. We need to keep abreast of all of the options so we can offer our clients the most appropriate solution.

MWJ –Looking to the near future what technologies or new sectors of the market can you see potential for Plextek RF Integration to exploit?

LD –As I mentioned previously we’re seeing increasing demands for GaN solutions. Whilst GaN ICs are more expensive per unit area than competing microwave power technologies such as PHEMT, the power density of the transistors is around 5 or 6 times higher so an IC offering comparable performance can be smaller. Additionally GaN is a maturing technology and we’re seeing significant year on year cost erosion. We feel there is a lot of potential in using GaN PAs for line of sight link applications and this is an area where we are active.

We also have experience of developing high power GaN switches and I expect to see increasing interest in developing multi-function GaN ICs such as gain/phase control ICs incorporating high power transmit capability. I also see mm-wave applications as a growth area. The wider operating bandwidths allow higher data-rates and help satisfy the consumer’s insatiable demand for wireless data.

MWJ –Finally, how easy is it for an independent design house based in the UK to successfully compete on the global stage?

LD – Around 70 per cent of our business is export so the global market is vital to us. The key is to offer a service that’s in demand, to be able to present clear evidence of your successes with relevant examples of past designs and to market yourself effectively on a global scale.