Reducing far-end crosstalk in chip-to-chip communication systems and components

Abstract

The present invention involves chip-to-chip communication systems for reducing Far-End Crosstalk (FEXT) through the use of novel polarity swapping to negate the cumulative effect of FEXT. Skew adjustment is used to improve the FEXT cancellation from polarity swapping. The polarity reversal location or locations among FEXT sources are optimized to achieve maximum FEXT cancellation. The novelty polarity swapping technique can be applied to a wide variety of systems that can benefit from FEXT reduction.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This regular U.S. patent application is based on and claims the benefit of priority under 35 U.S.C. 119 from provisional U.S. patent application No. 61 / 146,614, filed on Jan. 22, 2009, the entire disclosure of which is incorporated by reference herein.FIELD OF THE INVENTION[0002]This invention relates in general to systems for reducing Far-End Crosstalk (FEXT) and, more particularly, towards the reduction of FEXT in chip-to-chip communication systems that are transmitting differential signals and may include both differential and single-ended signals.DESCRIPTION OF THE RELATED ART[0003]As the circuit speed increases, differential signaling has become a preferred method for data transmission in such applications as personal computers, servers, switches, and routers.[0004]For the differential victim pair being considered, unwanted electromagnetic coupling (i.e., crosstalk) from neighboring aggressor pairs occurs throughout the data transmiss...

AI Technical Summary

Benefits of technology

[0007]FEXT is a cumulative effect, and if there is more than one FEXT generator in the data transmission path (i.e., channel), the neighboring differential pair's polarity will be swapped at least once through a simple routing change. The swapping of neighboring pair's polarity results in the phase change of the following FEXT generators, so the cumulative FEXT from the following FEXT generators will cancel the cumulative FEXT from the preceding FEXT generators. Such polarity swapping, which is independent of inductive or capacitive coupling, can be applied to a chip package, a connector, a printed circuit board (PCB), or any differential system that experiences FEXT. Low-crosstalk chip packages and connectors can be designed with polarity swapping built-in. Systems with large individual FEXT components can also see big improvements in total FEXT by applying one or more embodiments of the invention.

[0011]Additional aspects of the present invention include a system that includes a transmission end, a receiving end, at least one single ended signal line, at least one differential pair connected to the transmission end and the receiving end, the differential pair comprising a positive signal line and a negative signal line, wherein the skew among differential pairs and single-ended signals is minimized to improve FEXT cancellation.

Problems solved by technology

However, such attempts have been relatively insufficient in reducing FEXT, particularly in higher frequency systems.

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