High-speed signal compensation on printed circuit boards

Data transfer rates on printed circuit boards have approached speeds that challenge the limits of today's technology. Chip-to-chip digital communication has reached a plateau at 3 Gbit/s and several problems need to be addressed to significantly increase data transfer rates. Crosstalk between adjacent signal lines increases with increasing frequency. With far end crosstalk (FEXT), inductive and capacitive components conveniently cancel each other as they propagate on an interconnect transmission line. However, with near end crosstalk (NEXT), these components add together and interfere with signals on adjacent receivers. This paper proposes a solution for canceling crosstalk by adding extra circuitry to the receiver within the integrated circuit. The digital circuit delivers one of three appropriate levels of crosstalk compensation to the incoming signal. Since the compensation circuit is of low complexity, it can be efficiently integrated into existing CMOS designs.