Combating Closed Eyes – Design & Measurement of Pre-Emphasis and Equalization for Lossy Channels

On-Demand Webcast †

Speaker: Tom Waschura, Co-founder and Chief Technology Officer, SyntheSys Research, Inc.

Hosted by EDN • OCT 2007
ON-DEMAND WEBCAST – Registration required.

This seminar introduces the need for pre-emphasis and equalization for high-speed serial communication over lossy channels such as backplanes, cables and connectors. In order to overcome the inter-symbol interference caused by frequency dependent channel losses, inverse transfer functions can be computed and applied at various points of the signal processing to enable error-free bit detection.

Circuits are described that implement inverse transfer functions such as pre-emphasis and equalization, and that include digitally clocked finite impulse response filters, linear finite impulse response equalizers as well as decision feedback equalizers (DFE). Following the theoretical filter development, examples are presented that derive optimized impulse response filter taps from step response or frequency domain network analysis measurements. Measurements are discussed and examples are used from standards such as PCI Express Generation 2.

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