Electronic Design

Tools Allow SERDES Model Evaluation And Development

Serializer/deserializer (SERDES) links are becoming increasingly popular due to the fact that such schemes, which reconstruct the transmit clock at the receiver from the data signal, cut down on the number of signal conductors while achieving accurate clock-to-data timing. SERDES links also reduce device pin counts and mitigate noise issues associated with single-ended signaling. However, there are no standards at present for modeling SERDES transmit/receive equalization and clock-recovery behavior. Designers seeking to simulate SERDES devices are left with proprietary tools from IP vendors or whatever they can cobble together themselves.

The IBIS Advanced Technology Modeling (IBIS-ATM) task group has been working since 2006 to define an industry standard for modeling SERDES equalization and clock recovery. Such a standard must support interoperability, allowing a set of models to run across multiple EDA platforms and enabling SERDES models from different IP vendors to run together in the same simulation.

To support the IBIS-ATM effort, Signal Integrity Software Inc. (SiSoft) is planning to distribute an IBIS-ATM Evaluation Toolkit. Using the kit, interested parties can evaluate and develop models based on the proposed IBIS-ATM standard for SERDES modeling and channel analysis. This toolkit will include a "simulator" utility that allows IBIS-ATM models to be run as standalone executables, a fully functional SERDES transmitter model, documentation, and a sample set of analysis data. These are the first tools and models to become publicly available as part of the proposed standard.

The toolkit will serve four important functions. For one, users will be able to run sample simulations using the included transmitter model, assessing the impact of transmit equalization on channel behavior. Users also can analyze receiver behavior by providing additional models.

A second function is the provision of a "reference implementation" for the simulator/model interface defined in the IBIS-ATM proposal. This will allow users experiencing problems with a particular EDA tool/model combination to assess the source of the problem.

Thirdly, the toolkit will give IBIS-ATM model developers the opportunity to develop and test models in a controlled environment. The "simulator" utility can also document a model’s intended behavior and produce a set of reference results.

Finally, the toolkit provides a starting point for model development. The transmitter model in the toolkit will include source code that model developers can leverage to develop their own device-specific models.

SiSoft is asking other members of the IBIS-ATM task group to review the kit before general release, to help assess current EDA tool and model interoperability. SiSoft will turn over ownership of the toolkit to the IBIS Open Forum as part of the formal standardization process later this year, allowing the toolkit to become the "golden" reference platform.

More information on the IBIS-ATM Evaluation Toolkit (including sample simulation results) can be found at:

http://www.eda-stds.org/pub/ibis/macromodel_wip/archive/20070717/toddwesterhoff/IBIS%20ATM%20Validation/IBIS_ATM_Validation.pdf

SiSoft
www.sisoft.com

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