Industry Summary Articles

Lumerical Inc. announces the immediate availability of CML Compiler, which enables foundries and IP developers to automate the creation, QA testing, and revision control of photonic compact model libraries (CMLs). CML Compiler allows photonic CML developers to develop high-quality photonic model libraries for use in Lumerical’s photonic integrated circuit simulation environment, INTERCONNECT, and with popular Verilog-A simulators.

A key step in the transition of photonics from research to commercial production is the delivery of photonic foundries’ technology to their customers through photonic process design kits (PDKs). Photonic PDKs typically contain simulation models, schematic symbols, and the layout geometries for a key set of passive and active components specific to the sourcing foundry for use with popular photonic and EDA design tools. Customers who design with a foundry PDK are assured that the resultant design can be manufactured at that foundry. Fully established in electronics, PDKs are a relatively new development in photonics so foundries and photonic design tool companies have been teaming up to develop and deliver them.

To date, the most challenging aspect of photonics PDKs has been delivering accurate compact model libraries for system simulation. Data formats and exchange mechanisms have been ad hoc, resulting in varying levels of quality and lengthy development cycles. CML Compiler resolves this issue by defining a specific data schema, which accepts multiple data formats common to foundries including JSON and MathWorks’ .mat, and by rapidly producing the complete set of models typical in a foundry PDK for both Lumerical INTERCONNECT and for compliant Verilog-A simulators from leading EDA vendors. Data derived from simulations, using for example Lumerical’s own leading simulation tools, and experimental data is accepted as input. To enable sharing while simultaneously protecting the foundry’s intellectual property, the models produced by CML Compiler are encrypted uniquely to the sourcing foundry.

Lumerical is working with leading EDA partners to ensure encrypted models run seamlessly in their respective Verilog-A simulators. Gilles Lamant, distinguished engineer at Cadence Design Systems said, “Cadence has worked extensively with Lumerical to deliver a strong integration between Lumerical tools and the Cadence Virtuoso custom IC design platform and Spectre AMS Designer simulators. The Verilog-A models produced by the Lumerical CML Compiler leverage the same data that is used to create the optical models for Lumerical INTERCONNECT, ensuring consistency of simulation results, regardless of the simulation approach.”

Building high-quality Verilog-A models that match their INTERCONNECT counterparts required overcoming some well-documented and known limitations of applying Verilog-A to modeling photonic components. As a result of several breakthroughs, Lumerical has filed U.S. Provisional Patent Ser. No. 62/776,067, “SYSTEM AND METHOD FOR CREATING A SINGLE PORT INTERFACE FOR SIMULATING BIDIRECTIONAL SIGNALS IN CIRCUITS USING AVAILABLE CIRCUIT SIMULATION STANDARDS”.

James Pond, CTO of Lumerical commented, “Over the past couple of years, we have built significant experience as foundries look to us to develop the models for their photonics components. We have put the knowledge we have gained into CML Compiler so that foundries can leverage it without building up and training large modeling teams. To address the distinct users active within PIC development, we have designed CML Compiler to produce both INTERCONNECT photonic models and their Verilog-A counterparts, which allows design teams to work in their simulator of choice, appropriate for their stage of the design cycle, while having confidence that the models have been built from the same underlying data.”

CML Compiler also simplifies the substantial task of model quality assurance (QA) by using a well-defined data schema and providing the test cases for the produced models, another substantial time saver for the foundry. CML Compiler provides test automation by generating and automatically running test cases in the circuit simulator to QA test that the models perform as specified.

Ashkan Seyedi, Research Scientist at Hewlett Packard Labs, said “We are working to enable a democratized, horizontal silicon photonics PDK business with our foundry partners to drive volume and adoption of our technology. Protecting the IP of Hewlett Packard Enterprise (HPE) and our foundry partners is critical to reaching this goal, and CML Compiler allows us to do so by its inherent encryption and seamless integration into modern EDA simulation tools. Not only does CML Compiler generate the entire model library in seconds, entire photonic circuit-level simulations using both INTERCONNECT and Verilog-A models generally complete in a matter of seconds, which is a step towards reducing design cycles from months to weeks.” 

CML Compiler has been in use internally at Lumerical for nearly two years and has been utilized successfully to generate production PDKs for such foundries as AIM Photonics, imec, CompoundTek, and TowerJazz and others. Lumerical is now making the proven CML Compiler available to foundries, IP providers and end users for their direct use.

Mr. K.S. Ang, Chief Operating Officer of CompoundTek remarked, “As we are driving the move of Si photonics to commercial applications, delivering quality PDKs to our customers is critical. We are silicon experts, rather than modeling experts, and Lumerical has been an excellent partner for us to deliver the simulation models. Now we will be able to access their modeling expertise encapsulated in CML Compiler and deliver the models ourselves. Our customers use both Verilog-A and Lumerical INTERCONNECT at various stages of their designs and it is critical that they give consistent results, as CML Compiler enables.”

CML Compiler including support for INTERCONNECT and Cadence Spectre is available immediately from Lumerical at https://www.lumerical.com/products/cml-compiler/

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