Designing for FlexICs vs designing for silicon

FlexICs may be the new tech on the block, but if you’re used to silicon development, the design process will feel reassuringly familiar, says Dave Verity, Senior Director, Design Platform.

For decades, silicon has been the foundation of the semiconductor industry. The tools, methodologies, and design flows built around it are mature, powerful, and deeply embedded in engineering practice.  

FlexICs – flexible integrated circuits built on a flexible substrate – are, relatively speaking, the new kid on the block. So if you’re thinking of applying your silicon design skills to FlexICs, what’s different, and what’s the same?  

The short answer is that much of it will feel reassuringly familiar – by design. 

Designing for FlexICs: what feels the same 

A core principle behind FlexIC technology is lowering the barrier to entry. If you’re experienced in silicon design, you shouldn’t feel as though you’re starting from scratch.  

The Process Design Kit (PDK) for Pragmatic FlexIC Platform Gen 3 has been developed to work with the same industry-standard computer-aided design (CAD) and electronic design automation (EDA) tools you probably already use, including those from Siemens and Cadence. This means you can bring your existing skills and workflows with you. 

The look and feel of the technology also mirrors the silicon design experience. Layers and devices are named in a similar way, and the structure of the PDK reflects conventions that will be intuitive to anyone familiar with mainstream silicon processes. Industry-standard compact models accurately represent the electrical performance of the FlexIC technology and enable ‘first time right’ product design for process-, voltage- and temperature (PVT)-induced variability.  

This intentional familiarity reduces friction and helps you to be productive quickly. 

Reliability as standard

Manufacturability is also built in. As with silicon, the PDK does more than provide models – it embeds the rules to ensure that your design can be reliably manufactured and will meet its intended mission profile. Reliability considerations are integrated into the design framework, rather than treated as an afterthought. 

Standard cell IP is also provided, giving designers familiar with mainstream silicon processes an efficient route for digital design. This makes it easy to port existing workflows and behavioural models into FlexIC technology.  

We also provide a rich and detailed body of documentation to accompany the technology. This includes clear explanations of design rules, model fits, and guidance on how best to approach layout and optimisation. While some aspects of layout differ from traditional silicon, the documentation and application support are there to guide you through those differences step by step. 

Importantly, the overall design flow remains aligned with what silicon designers know. From schematic capture to simulation, layout, and verification, the tools and stages are structured so that you can port your existing silicon design flow onto FlexIC technology with minimal disruption. 

What’s different?

The most significant technical difference is that the platform is currently NMOS only. This requires a different mindset compared with conventional CMOS design, where complementary NMOS and PMOS devices are available by default. 

For designers, this is less a limitation and more an invitation to think creatively. Established techniques can be adapted, and new approaches explored, to achieve the required functionality within an NMOS-only environment. A skilled and inventive designer can extract significant capability from the technology, often in ways that suit the unique applications flexible electronics enable. 

At the same time, this is an evolving platform. PMOS devices are on the roadmap for future generations of the technology, which will further expand design options and enable even greater parity with traditional silicon approaches over time. 

Designing for flexible form factors 

Where FlexICs diverge most clearly from silicon is not in the CAD environment, but in what they make possible. Designing for physically flexible substrates and ultra-thin form factors opens up application spaces that rigid silicon alone cannot address. This may influence architectural decisions, power budgets, integration strategies, and system-level thinking. 

For many designers, the experience is one of continuity rather than disruption. The foundations – tools, flows, naming conventions, documentation, and manufacturability frameworks – are intentionally aligned with silicon practice. The differences lie in the new physical possibilities the technology enables. 

In that sense, designing for FlexICs is not about replacing silicon. It is about extending the designer’s toolkit into new domains, while building on the skills and experience that the semiconductor industry has developed over decades.

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