When SPICE Alone No Longer Works

Blog Post created by kaelly_farnham Employee on Jan 4, 2017

When SPICE Alone No Longer Works, Channel Simulator Technology May Help


As a designer, chances are you’ve been there. You’re measuring the margin-to-mask for really low bit-error-rates (BER), a task required for high-speed link designs, and the transient simulation (SPICE) you’ve been using no longer seems to work. What are your options? Channel Simulation, as found in Keysight ADS Software, and improved upon in the latest ADS 2016 release, provides a trusted solution.


Before Channel Simulation, the common approach used to simulate a high-speed link design was transient simulation. But, that left designers struggling with questions like: What margin do I have at a BER of 1e-9, 1e-12 or 1e-16?  Transient simulation alone could not deal with these questions because the sheer number of time steps required was beyond practical means.


What margin do I have at a BER of 1e-9, 1e-12 or 1e-16?


The answer to overcoming that hardship lies in being able to compute BER contours with Channel Simulation, a solution built on a strong foundation of technical innovation. Beginning with Dr. Fangyi Rao’s 2006 patent to correct for passivity, while ensuring causality, in bandlimited frequency-domain models, Keysight ADS established itself as the industry-leading Channel Simulator. Using it, you gained access to an accurate solution capable of handling cascades of S-parameter models combined with circuit models in one schematic. In 2009, bit-by-bit channel simulation was released. In 2010, statistical channel simulation was released. In 2011, IBIS-AMI support for channel simulation was introduced. The pace of innovation continues even today, and ADS's channel simulator is widely regarded as the industry standard. 

 IBIS, ADS 2016, Channel Simulator, signal integrity, SPICE

Figure 1. In addition to allowing designers to mix-and-match models, ADS 2016 Channel Simulator now supports IBIS package (.pkg) entries directly, and more extensively than before. It also offers pre-standard support for IBIS v6.1, even before the official IBIS parser is available. Get a free trial of ADS 2016


As the high-speed link designer, you can now freely mix and match models from IBIS, IBIS_AMI and SPICE, as well as generic built-in models (Figure 1). You can even access the Channel Simulator’s own IBIS-AMI Tx and Rx models for PCIe3, USB 3.1 and 100 GbE, which ship with Compliance Test Benches and example workspaces (Figure 2 and 3). Such capabilities are crucial when SPICE alone simply no longer works. 

 channel simulation, M-PHY simulation, NRZ signaling, ADS 2016

Figure 2. ADS 2016 provides a template for MIPI C-PHY, D-PHY, and in this case, MIPI M-PHY simulation. Get a free trial of ADS 2016.


channel simulation, PCIe3, BER contours, equalization, ADS 2016, Compliance Test Bench

Figure 3. ADS 2016 features PCIe3 standard-specific EQ presets, which have been added to the PCIe 3 Compliance Test Bench. Get a free trial of ADS 2016.


For more information on measuring margin-to-mask in high-speed link design when SPICE alone no longer works, check out 8 Ways ADS 2016 Helps You Overcome Signal and Power Integrity Challenges.


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