Misao Fukuda

A line terminating LSI using echo cancelling method for ISDN subscriber loop transition

A 144-kb/s digital subscriber loop (DSL) transmission system based on hybrid transmission with an echo cancelling method is described. It incorporates advanced LSI technology to obtain compactness, low cost, and high reliability. An echo canceller (EC) LSI has been developed using CMOS technology. Combined with the multiplexing processor (MXP) LSI, the EC LSI provides basic DSL equipment functions. A specially arranged frame format with a newly developed digital phase-locked loop (DPLL) circuit for stable timing extraction, an automatic balancing network, and a two-stage echo canceller characterize the system. Using this line termination circuit, the DSL equipment showed a reach of over 6 km when used with 0.5 mm diameter cable for 160-kb/s bidirectional digital transmission. >

An approach to LSI implementation of a 2B1Q coded echo canceler for ISDN subscriber loop transmission

An approach to large scale integration (LSI) implementation of the 2B1Q echo canceler for an integrated services digital network (ISDN) basic access interface is described. A hybrid architecture, using both analog and digital processing, is adopted for LSI implementation with a moderate circuit scale. Techniques using baud-rate sampling, such as square root f automatic gain control (AGC) equalization by power detection, timing extraction by peak estimation and a two-stage echo canceler with divided tables, are introduced to the system. Performance characteristics are also confirmed by computer simulation and a prototype system.<<ETX>>

A Line Termination Circuit for Burst-Mode Digital Subscriber Loop Transmission

This paper describes a line termination circuit for burst-mode bidirectional digital subscriber loop transmission. It incorporates the most advanced LSI technology to obtain compactness, low cost, and high reliability. Two CMOS LSIs have been developed; one is a line termination LSI (LT) and another is a circuit termination LSI (CT). LT LSI adopts a novel RC active filter-type equalizer and decision feedback bridged tap equalizer suitable for incorporation in LSI and provides high performance. By using these LSIs, a line termination circuit realizes a reach of over 5 km at 88 kbit/s bidirectional digital transmission. This paper describes each LSI and shows total performance characteristics in detail.