Want to learn how to do the placement of devices in the advanced node designs?

Virtuoso Placer is designed for you! Using Virtuoso Placer, you can ensure placement that is correct by construction.

In this Knowledge Booster blog, we will talk about the Virtuoso Placer menu and explore the steps involved in creating a layout using row-based placement methodology.  

What is Virtuoso Placer?

Virtuoso Placer is a unified placement solution that can be used to achieve quick, high-quality, DRC-correct placement of standard cells and devices. It supports the placement of different types of designs, such as digital designs with only standard cells, analog designs with only devices, and mixed designs that contain a mixture of both. It can also be used to generate connectivity and constraint-driven device placements. Virtuoso Placer combines several advanced features, such as snap patterns, width spacing patterns, and multi-patterning into a single automated flow. At the core of the Virtuoso Placer is the row template infrastructure that lets you create rows, which, in turn, define how standard cells and devices are placed. Rows, if made compatible with snap patterns, help achieve correct-by-construction placement.

The key benefits of Virtuoso Placer are:

• Accelerated layout productivity for advanced node placement.
• Unified GUIs and use-models between the various placers.
• Improved usability of the setup and placement commands.

Virtuoso Placer is available in the Virtuoso Layout Suite EXL cockpit in advanced node releases.

Virtuoso Placer Flow

Virtuoso Placer is a unified, powerful placement solution that supports the placement of different types of designs, such as digital designs with only standard cells, analog designs with only devices, and mixed designs that contain a mixture of both.

The following figure depicts the Virtuoso Placer flow and maps each step to the corresponding Virtuoso feature.

The following GIF demonstrates the steps involved in creating a layout using row-based placement methodology.

Introduction to Row Infrastructure

Advanced node processes support multiple grid types. As a result, advanced node designs easily adapt to row-based placement methodology. A row represents the location for placing standard cells, macros, or devices. In a layout design, you define rows within the PR boundary. You can then place instances within these rows. Though it is not necessary that you create rows for placement, it is recommended because row-based placement improves routability, achieves better wire length after routing, and resolves illegal placements by balancing the number of instances placed in each row. It also helps resolve overlaps between devices in each row. 

The Row Template Manager feature provides the capability to define row templates. You can create row templates specific to your design type and then use these templates to generate rows in the layout canvas. Rows are created in objects called row regions. Row regions reference a row template that determines how rows are created in that region. Rows, in turn, contain component-type attributes that determine which instances are placed in that row and the way they are placed. You can save row templates and reuse them in multiple designs. Row templates can be used to place both analog and digital designs.

Virtuoso Placer Support for Modgens

When you run Virtuoso Placer, Modgens are automatically snapped to compatible rows if they exist. If the Modgen instances do not align exactly with the rows, one of the Modgen instances is snapped to the nearest row.

Support for Modgen On-Canvas Commands

You can use the various Modgen on-canvas commands that are available under the Place– Modgen menu to perform simple editing operations directly in the layout editor without invoking the Modgen Editor. For example, you can use the Split Modgen Rows and UnSplit Modgen Rows commands to ensure that Modgens use as few rows as possible while still fitting comfortably inside the PR boundary.

Support for Modgen Pattern Editors

The Grid Pattern Editor (GPE) and Grid Pattern Mapping (GPM) assistants are available on canvas. Modgen grids directly map to the rows in the layout canvas. Therefore, whenever you make changes to the grid pattern, Modgen instances always snap to the nearest rows.

Guard Rings in Virtuoso Placer Flow

In the Virtuoso Placer flow, it is recommended to use either identical guard rings or MPP guard rings. Fluid guard rings can be created, but they are not compatible with the row infrastructure.

To learn how to do correct by construction placement, click to play the videos in the placement by using row-based methodology channel on the Cadence Online Support Portal.

What’s Next?

On the Cadence Learning and Support site (login required), you can:

• Take the free Virtuoso Layout for Advanced Nodes: T1 Place and Route vICADVM20.1 (Online) online course
• And earn a Digital Badge by passing an exam for the course.

Related Resources

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About Knowledge Booster Training Bytes 

Knowledge Booster Training Bytes is an online journal that relays information about Cadence Training videos, online courses, and upcoming webinars that are available in the Learning section of the Cadence Learning and Support portal. This blog category brings you direct links to these videos, courses, and other related material, on a regular basis. Subscribe to receive email notifications about our latest Custom IC Design blog posts.

Sandeep O

On behalf of the Cadence Training team