Crosstalk Control Of High Speed Lan Connectors

摘要

NEXT (Near End Crosstalk loss) and FEXT (Far End Crosstalk loss) of a high speed LAN connector are analyzed using a simple coupled line model and examined experimentally. "Crosstalk Chart" is also proposed, by which, the NEXT and FEXT can be easily read off from the mutual inductance and unbalanced capacitance between pair of lines. This approach is effective for Cat.5c 1 connectors. However, for Cat.6 2, of which transmission bandwidth is widen to 250 MHz, some additional adjustments of path pattern on the jack and terminals PCB are required. In order to assist such the adjustments, a new simple measurement technique to grasp the complex crosstalk characteristics is proposed. Two examples are introduced. One is a conventional telephone rosette, which is enhanced to be co-usable for a Cat.5e LAN connector, where only its original circuit board is reengineered. Another is a Cat.6 connector of which PCB is modified from a conventional Cat.5e connector.