Software provides trusted simulation engine for PAM-4
Published: 4 December 2015 - Lisa Peake
Keysight Technologies announces a four-level pulsed amplitude modulation (PAM-4) capability for the Keysight EEsof EDA Advanced Design System (ADS) Channel Simulator. The introduction of this capability further advances Keysight’s leadership position in IBIS-AMI SerDes channel simulation.
With Keysight’s new ADS PAM-4 capability, system designers can now use PAM-4 IBIS-AMI models within the industry standard ADS Channel Simulator. Developed in collaboration with leading PAM-4 SerDes IC vendors, the ADS Channel Simulator provides a trusted bit-by-bit simulation engine for PAM-4. The new technology enables system designers to easily compare the various design tradeoffs between non-return-to-zero (NRZ) and PAM-4 signaling technologies.
“Working closely with leading SerDes vendors and the IBIS Open Forum to define and validate our channel simulation approach for PAM-4, we’ve developed a highly accurate solution for PAM-4 measurements,” says Stephen Slater, product manager for Keysight EDA. “Our software solution relies heavily on our measurement expertise and leadership in IBIS-AMI SerDes channel simulation. It’s that measurement expertise that makes Keysight uniquely equipped to guide system engineers from simulation all the way through to test and measurement of real hardware.”
PAM-4 is a signaling technology utilized for high-speed SerDes links over electrical backplanes that are attempting to deliver a data rate of greater than 56 Gbps per lane. For system designers, a key challenge with PAM-4 is simulation accuracy during serial-link design. Traditional EDA software simulations only consider 2-level signaling. PAM-4 signals however, are affected by conventional impairments (e.g., jitter, noise, channel loss and inter-symbol interference) in unconventional ways; only for the resulting eye measurements to be further complicated by new receiver behavior (three slicer thresholds, individual slicer timing skew, equalization, and clock and data recovery) introduced to minimize the symbol error rate. Accurately understanding how each of these variables influence specific design trade-offs for PAM-4 links requires a channel simulator with the ability to handle PAM-4 IBIS-AMI models from SerDes vendors.
The ADS Channel Simulator with PAM-4 capability features a number of new built-in measurements that can capture effects such as slicer threshold levels and how they adapt over time, timing skew for each slicer, and multi-tap decision feedback equalization. The software’s accurate measurement techniques specifically provide the symbol-error-rate contours for each PAM-4 eye.