A 2.5 Gb/s adaptive cable equalizer

High-rate data communication over cable suffers from intersymbol interference (ISI) introduced by the cable. This ISI can be greatly reduced if the receiver includes a cable equalizer. Usually, the equalizer is adaptive to track changes in the cable length. The prior high-speed cable equalizers are either implemented in GaAs and are fixed, or operate to a maximum of a few hundreds of Mb/s. This adaptive equalizer is fabricated in a 14 GHz bipolar process, and including all auxiliary circuits draws 48 mA from a 5 V supply. The measured jitter of the equalizer with a 2/sup 23/-1 pseudo-random NRZ sequence at 1.5 Gb/s is less than 54 ps pp (10.6 ps r.m.s.) for up to 100 m of Belden 8281 cable (140 m of Belden 1694 A ). This is less than 0.1 unit interval (UI) peak-to-peak. At 2.5 Gb/s, the jitter increases to below 80 ps pp (0.2 UI) for up to 110 m of 8281 (155 m of 1694 A ). The equalizer is recommended for the 1.485 Gb/s serial digital video interface in HDTV applications, where it outperforms a previous solution by a factor of two.