In photonic integrated circuit (PIC) design, the Mach-Zehnder Interferometer (MZI) stands as a foundational building block. Whether used for modulation, switching, or sensing, its ability to manipulate light through interference makes it indispensable. Traditionally, schematic creation has been a manual and often tedious process, especially when dealing with complex waveguide geometries and thermal tuning elements. Enter the Place-Like Layout Schematic feature in Virtuoso Studio IC25.1—a transformative tool that bridges the gap between physical layout and schematic representation, streamlining the design process for photonic engineers.

Picture yourself designing an MZI with two thermal phase shifters. In the physical layout view, you see the waveguides splitting and recombining light, with heaters placed strategically on the arms to induce phase shifts. The layout is rich in detail—curved waveguides, abutted components, and precise spatial relationships. This view showcases the physical beauty and complexity of your design.

The Magic of Place-Like Layout Schematic

Now, lets switch to the Place-Like Layout Schematic view. Instead of a linear, abstract representation, the schematic mirrors the physical layout. The Y-splitters, waveguide arms, and thermal phase shifters are placed in positions that reflect their actual physical arrangement. Connectivity is auto-routed, and symbols are generated to match the layout components. This visual fidelity makes the schematic intuitive, reducing debugging time and enhancing design clarity.

Bridging the Gap

The Place-Like Layout feature in IC25.1 enables designers to generate schematics that visually resemble the physical layout of photonic devices. Photonic schematic symbols often resemble their layout counterparts, so arranging the schematic instances based on the layout can make the schematic easier to interpret and debug. This tool bridges the gap between the two views for complex waveguide designs, simplifying interpretation, aiding debugging, and increasing productivity, reducing a tedious manual task to a few clicks.

Integration in Virtuoso

Place-Like Layout is part of the broader Virtuoso System Design Platform and is found within Virtuoso Studio. It is part of the Virtuoso_Photonics_Platform license, making it a valuable tool for custom photonic design. This feature enables better integration and co-design of both schematic and physical views.

How It Works

The Place-Like Layout feature operates within a layout-driven schematic flow, reversing the traditional schematic-driven layout paradigm. Here's how it unfolds:

1. Enable Photonics Platform: Ensure the Virtuoso_Photonics_Platform environment variable is set and the appropriate license is active.
2. Start in Layout EXL Workspace: Open the layout of your MZI cell view.
3. Generate Schematic from Layout:     

Select the layout instances.

Use the “Generate selected from layout” icon.

Drag to the schematic window and press F3 to open the Generate selected from layout

Choose Placement Mode: “Place-Like Layout”.

Place instances in the schematic according to the layout placement.

  Auto-Connect Waveguides: Abutted instances in the layout automatically connect in the schematic, preserving net integrity.

In conclusion, whether you're a seasoned PIC designer or exploring photonics for the first time, this feature empowers you to design with confidence, clarity, and creativity. The Place-Like Layout feature in Virtuoso Studio IC25.1 revolutionizes the way you design and interpret photonic integrated circuits. By bridging the gap between physical and schematic views, it enhances both functionality and aesthetic appeal, making your design process more efficient and enjoyable. Happy designing! 

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Thanks,
Ssandhya P Shet