Measurement-based models for crosstalk within a connector shell

Abstract

Crosstalk within cable bundles can degrade system performance. In systems that use shielded twisted-wire pairs, the crosstalk occurs primarily in the connector, where individual signal wires are not shielded or twisted. In many cases, the parameters which determine crosstalk within the connector are unknown, in part because the connector is closed and wires cannot be accessed. A methodology was developed for measuring coupling parameters and modelling crosstalk within the cable connector at low frequencies (<; 300 MHz). The values of mutual inductance and capacitance were extracted from measurements made with a Vector Network Analyzer. Values of self inductance or capacitance within the connector for individual wires were extracted from TDR measurements. The accuracy of the model was evaluated through comparison of simulated and measured results. Tests were performed while varying the wire terminations to modify the dominant coupling mechanism. A further simplified model which only takes into account the mutual coupling was also developed to estimate the envelope of the crosstalk. The simulated results match the measured results well. This simple SPICE model allows effective evaluation of the impact of crosstalk within different connectors.