Modular Magic: Accelerate Chip Design with Genus Bottom-Up Flows

6 Jan 2026 • 6 minute read

Let's face it: tackling a modern SoC design top-down is like trying to eat a triple-layer cake in one bite—messy, overwhelming, and likely to end with frosting on your keyboard. Enter the Bottom-Up Flow in Cadence's Genus Synthesis Solution: the engineering equivalent of slicing that cake into perfect, manageable pieces (and yes, you get to eat them, too).

But what is bottom-up flow, really? Imagine you're assembling a spaceship, but instead of building the entire thing in your garage, you have expert teams crafting the engines, wings, and cup holders separately. Each team delivers a ready-to-use module—sometimes as a macro (.lib) and sometimes as an ILM (Interface Logic Module)—and the Genus solution lets you snap them together at the top level, without requiring duct tape.

From a technical perspective, a bottom-up flow in Genus means:

You can synthesize subblocks independently, generating accurate timing and physical models (ETMs, ILMs, LEFs, DEFs, and more).
These pre-synthesized blocks are then integrated into the top-level design, eliminating redundant synthesis and conserving precious CPU cycles.
Genus supports multiple flavors: macro-based (.lib) logical and physical flows, and ILM-based logical and physical flows—including seamless integration with Innovus and iSpatial for physical-aware modeling.
The result? Faster design closure, improved QoR, and the ability to parallelize work across teams—so you can finally leave the office before your coffee gets cold.

And the best part? You don't have to learn all this by deciphering ancient scrolls or cryptic command-line errors. We've a series of training videos that break it all down with clarity, practical examples, and just enough technical spice to keep things interesting.

Are you ready to conquer design complexity, impress your team, and maybe even make your coffee machine jealous of your efficiency? Welcome to the world of Bottom-Up Synthesis Flows in Genus—where modular design meets maximum productivity, and learning is just a video away!

Why Bottom-Up? Because Top-Down Is So Last Season

Modern chip design is akin to assembling a spaceship from the blocks—except the blocks are RTL modules, and the stakes are much higher. Genus Synthesis Solution's bottom-up approach enables you to break down massive designs into manageable subblocks, synthesize them independently, and then assemble them at the top level. The result? Faster iterations, better quality of results (QoR), and less hair-pulling for everyone involved.

Bottom-Up Wisdom: Tips, Tricks, and Gotchas

Parameterized Modules: Prevent parameter mismatches from rendering your design a black box. Use the right Genus attributes to keep your modules linked and happy.
Complex Ports: Flatten those ports and align naming styles between subblocks and top-level designs for smooth sailing.
DFT and ILMs: If you're inserting DFT, remember to read subblock CTLs at the top level. For physical flows, stick with Innovus-generated ILMs.
Version Compatibility: Keep your Genus and Innovus versions in sync—think of them as dance partners who need to be on the same beat.

FAQs: Because We Know You'll Ask

Why use ILMs? They're accurate, fast, and make debugging a breeze.
Can ILMs be generated at any stage? Absolutely—prePlace, preCTS, postCTS, or postRoute.
What if I see warning messages? Check your settings, and if in doubt, visit the Cadence ASK portal for support.

Meet the Flavors: Macro-Based and ILM-Based Flows

Genus doesn't believe in one-size-fits-all. Whether you're a fan of macro-based (.lib) flows or the precision of ILM (Interface Logic Module) flows, there's a video for you:

What Is Bottom-Up Synthesis Flow? (Video): Start here! This video demystifies the bottom-up approach, explaining how pre-synthesized blocks (in formats such as gate-level netlists, .lib macros, or ILMs) can be reused without re-synthesis, saving you time and silicon-induced headaches.

How to Run A Macro-Based .lib Bottom-UpFlowin Genus Synthesis Solution? (Video): Learn how to generate Extended Timing Models (ETMs) for your subblocks and plug them into your top-level design. The logical flow is great for early project trials, but for accuracy, the physical flow (with Innovus-generated libs) is your best friend. Pro tip: Don't let your ETMs wander—keep them close and compatible

How to Run A Macro-Based .lib Bottom-Up Physical Flow in Genus Synthesis Solution? (Video): Physical flows sound intimidating, but this video makes them as approachable as a puppy at a hackathon. Discover how to generate both .lib and LEF files, and why using Innovus for ETM generation is the gold standard for accuracy.

How to Run An ILM-Based Bottom-Up Logical Flow in the Genus Synthesis Solution? (Video): ILMs are like the VIP passes of hierarchical design—compact, accurate, and only showing what's needed at the interface. This video demonstrates how to generate and utilize ILMs for logical flows, ensuring your top-level analysis is both robust and resource-efficient.

How to Run ILM-Based Bottom-Up Flow for Model Generation Within iSpatial Flow in Genus? (Video): Ready to go spatial? This tutorial walks you through generating ILMs during iSpatial runs, making model generation as smooth as your favorite playlist. Bonus: ILMs can be created at any stage—prePlace, preCTS, postCTS, or postRoute—so you're never out of sync.

How to Run ILM-Based Bottom-Up Physical Flow in Genus When ILMs Are Generated from Innovus? (Video): When Innovus and Genus join forces, magic happens. Learn how to generate ILMs in Innovus and seamlessly integrate them into your Genus physical flow. Remember: For physical flows, always use Innovus-generated ILMs for best results.

How to Run Macro-Based .lib Bottom-Up Physical Flow in Genus Using the .lib and LEF from the Innovus? (Video): Why settle for less? This video demonstrates how to utilize both .lib and LEF files from Innovus, ensuring your macro-based physical flow is as robust as your morning espresso.

Where to Watch These Videos

Head to the ASK portal for deep dive training bytes, courses, and sanity-saving tips that pair perfectly with your favorite debugging snack.

Related Courses

Please refer to the course learning maps, which provide a visual representation of courses and their relationships, and regional course catalogs.

Bonus Features

Enhance the Genus Synthesis Solution experience with short videos: Genus Synthesis Solution: Video Library.
Free Online Trainings: The Online Trainings are free for all Cadence customers with a Cadence ASK For instructor-led training sessions, "Live" or "Blended," don't hesitate to get in touch with Cadence Training.
Get ready for the most thrilling experience with Accelerated Learning!
Grab your Digital Badge after completing the training and flaunt the expertise you have built up.

Did You Already Know?

The Cadence YouTube channel hosts a Customer Education Training Bytes channel.

Here, you can view a variety of training bytes for which you do not need a Cadence ASK account.

Ready to Level Up?

Grab your favorite beverage, queue up these videos, and let Genus Synthesis Solution guide you to bottom-up brilliance. With these training bytes, you'll not only become an expert in the flows—you'll enjoy the journey (and maybe even crack a smile along the way).

Remember: In the world of synthesis, bottom-up isn't just a flow—it's a philosophy. And with Genus, you're always building towards success!