Case Studies

TANNER EDA MIXED-SIGNAL LAYOUT TOOLS BOOST PRODUCTIVITY, COMPLEMENT HIGH_END EDA AT CAMBRIDGE CINSULTANTS EDITORIAL

"We frequently push the capabilities of tools in our work and we need to be able to customize them when necessary. That's something that is easy to do with L-Edit Pro…" Richard Traherne, CCL Business Unit Manager for Wireless

Following Harold Wilson's call in 1960 for British industry to embrace the "white heat of technology", three Cambridge University students founded the first contract research, design and development company in the UK.

Today, Cambridge Consultants, LTD has grown into a world-wide leader in contract design and development providing services to a wide range of demanding market sectors including communications, healthcare, automotive and defense. Wireless product development has become a significant and fast-growing part of the company's business, spanning all these sectors and employing over 45 of the 230 design engineers based at their Cambridge facility. The company designs wireless systems and ICs for everything from professional radio to wireless video and next generation mesh networks, using leading edge technologies such as Bluetooth, ZigBee, UMTS, UWB, DAB, and even proprietary design for ultimate performance in specific applications.

Fig1: Cambridge Consultants design advanced mixed-signal chips for everything from professional radio to wireless video and mesh networks

CCL has also been the cradle for some of the UK's most successful providers of consumer and personal electronics. CSR, market leader in the Bluetooth silicon market, is one of the companyÕs notable spin-outs. Their products are used in over 60% of the world's qualified Bluetooth end products and modules. Another success from the Cambridge Consultants stable is Alphamosaic, whose advanced video processing ICs are set to revolutionize low power consumption mobile products.

Tool Flexibility, Design Productivity Not A Contradiction In Terms

Cambridge Consultants faces time-to-market pressure in every design they undertake, so productivity is critical in meeting customer expectations. 90% of designs are mixed-signal, and customers range from those with no capability or experience in ASIC design to those with substantial experience and their own in-house resources and workflows.

Some years ago, the company decided not to adopt a fully integrated EDA tools flow. Instead, they select optimum tools for their requirements at each stage of the process to provide the maximum performance, flexibility and usability demanded by their work. For layout, CCL has used Tanner EDA's L-Edit Pro in almost every design theyÕve created over the last 10 years, from low-volume designs for space applications to high-volume software radios. They have found L-Edit Pro to be a highly proficient and flexible, yet relatively low-cost PC-based tool for layout of analog and mixed signal designs. Tanner EDA has recently added some new features to L-Edit, including a browser for reading in DRC error log files produced by Calibre.

Fig2: L-Edit Pro facilitates working with other tools by including a browser for reading in DRC error log files produced by Calibre

Richard Traherne, CCL Business Unit Manager for Wireless, explains the thinking behind their approach. "Our philosophy is to select the most cost-effective tool for a particular engagement. Additionally, we have to be capable of managing a wide variety of jobs—our designs operate from DC to 5GHz."

"We frequently push the capabilities of tools in our work and we need to be able to customize them when necessary. That's something that is easy to do with L-Edit Pro; it's very straightforward to write our own device generators, for example. Another important consideration is the time it takes to learn to use, or re-acclimatize, with the tool. We have to pull design teams together very quickly, start projects quickly and deliver them quickly—L-Edit is a great help in that respect and its simplicity also reduces our need for CAD support," said Traherne.

Extra Control to Discover Potential Problems Early

Les Nuttall, CCL Senior ASIC Design Consultant, points to other advantages of L-Edit. "Inherently, as more complexity and automation is introduced into EDA tools you become more divorced from what's going on. Our design flow using L-Edit Pro means that we are able to view the design at a lower level than if we were using a more automated solution. This has the advantage of allowing us to use the tools in a more advanced manner and also to spot errors early and correct them early. This transparency is not so easy to achieve with more integrated tools," said Nuttall.

Not surprisingly, some CCL customers are wary of the issues associated with fragmented workflows. Additionally, those that have their own ASIC design flows (roughly 50%) want the company to match them as closely as possible for easy transfer of designs. However, if Cambridge Consultants were to adopt a high-end integrated design flow from one of the larger EDA vendors, it would disadvantage many of its other customers who want to develop in-house design capabilities on more limited budgets. Nuttall has found that the merging of their flow with existing design flows does not cause problems in practice.

"Some customers perceive that there is potential for errors at the interface of different tools, but this has never been a real issue. What is more important is clear visibility of what is going on within the tools and a robust design flow that maximizes the benefits of the individual tools, when they are brought together. We have developed our flow over many years and have an excellent track record of first pass success."

Laptop Portability A Big Plus

Traherne points out an added benefit of using a PC-based tool like L-Edit—its portability. "We have a Tanner commuter license enabled by dongle. This means we can work while we're travelling, at home, or at customer premises. It can sometimes be very useful to carry out live editing at customer premises and then check it out later, as we did recently when we needed to move a port over a couple of microns. Portability gives a boost to both customer service and design productivity, and itÕs something we would not be able to do with UNIX-based tools."

About Cambridge Consultants

Cambridge Consultants has for over 40 years enabled its clients to turn business opportunities into commercial successes, whether launching first-to-market products, entering new markets or expanding existing markets through the introduction of new technologies. With a team of over 200 engineers, scientists and consultants, in offices in Cambridge (UK) and Boston (USA), they offer solutions across a diverse range of industries including healthcare, industrial and consumer products, automotive, transport, energy and wireless communications.

About Tanner EDA

Tanner EDA is a division of Tanner Research, Inc., a privately held company headquartered in Pasadena, California. Tanner EDA was the first company to develop IC design software for the PC, and is the market leader in Windows® solutions for mixed-signal, analog and MEMS design work. Tanner tools L-Edit Pro and T-Spice Pro provide design entry, full-custom layout editing, placement and routing, LVS and DRC verification and mixed-signal simulation.