A single-chip 2B1Q U-interface transceiver

A single-chip transceiver designed to meet the American National Standards Institute (ANSI) requirements for the U-interface in the integrated services digital network (ISDN) is described. The device utilizes linear, jitter-compensated, and nonlinear echo cancellation and the 2B1Q line code to achieve high performance in the presence of near-end crosstalk and other impairments. The 2- mu m, single-metal, double-polysilicon, 5-V CMOS VLSI chip includes all the necessary analog and digital signal processing blocks for a network-termination of line-termination U-interface to be realized with the addition of a passive-line termination circuit and a transformer. Operation over 4.7 km of 0.4-mm cable or 7.5 km of 0.5-mm cable, with a bit error rate of 10/sup -7/, is possible.<
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