Yenra : Electronics : High-Speed Serial Bus De-Emphasis : Conversion of NRZ data for FB-DIMM, SATA, and PCI-Express

De-Emphasis

BERTScope Eye Openers from SyntheSys Research provide convenient and easy-to-use conversion of conventional non-return to zero (NRZ) data to de-emphasized data signals used by a growing number of high-speed serial bus standards.

Conventional NRZ data is modified by a passive network to produce data in which bits, following the initial one or zero bit in a sequence with multiple bits of the same value, are attenuated by a prescribed amount.

De-emphasis, which is often used in test and validation vocabulary, and pre-emphasis, which is commonly used in IC design and simulation, results in the same waveform shape. Instead of considering successive bits of the same value to be attenuated with respect to the first bit, pre-emphasis considers the first bit in a series of ones or zeros as sent with larger drive level than those following.

De- or Pre-emphasized NRZ signals are used by the latest high-speed serial bus standards to enable longer transmission distances between devices by reducing the effect of intersymbol interference due to frequency dependent loss in printed circuit board channels.