Crosstalk reduction in coupled microstrip lines using TT-shaped DMS approach

Abstract

The electromagnetic coupling between closely placed microstrip lines in compact and dense designs causes crosstalk which is undesired and hence should be minimized. In this context, several approaches have been evaluated in the literature, including via fencing, guard trace, guard trace with via, serpentine guard trace, serpentine guard trace with vias, serpentine microstrip lines, asymmetrically loaded microstrip lines, etc.; however, these structures require additional space between microstrip lines. Besides, some defective microstrip line structures (DMS) are proposed, which are difficult to fabricate, possess limited crosstalk improvement, and lag the rigorous DMS parametric analyses. Therefore in this regard, we propose a DMS approach consisting of arrays of the combinations of T and inverted T, etched on one of the coupled microstrip lines (CMLs), which alters the current path in the etched microstrip line, and this, in turn, reduces the coupling and hence reduces the crosstalk. In addition to the above, rigorous parametric analyses have also been performed, allowing the designer to tune the length of the structure to minimize the crosstalk at the desired frequency. Furthermore, the simulations of the TT-shaped DMS, performed on a 75x50mm RO4003 rogers PCB in the frequency range of 1-10GHz, show a minimum improvement of 12dB and a maximum improvement of 62dB, which outperforms the existing DMSs.