Investigation and Improvements of UWB Microstrip Delay Lines

Abstract

Microstrip ultra-wide band (UWB) delay lines consisting of a novel periodically loaded transmission line (PLTL) are presented, along with discontinuous structured guard lines (DSGLs). The distinctive advantage of the proposed approach is that the far-end crosstalk (FEXT) between the adjacent lines is effectively suppressed comparing to the conventional circuits. Afterward, the crosstalk of connected adjacent lines is effectively suppressed by modifying the DSGLs, since the current distributions are different from the separated adjacent lines. Subsequently, the strong reflection points are eliminated, which seriously deteriorate the performances in amplitude and group delay. Moreover, the serpentine delay line (SDL) and serpentine meandered delay line (SMDL) are studied, respectively, using the conventional microstrip (CMS) and the proposed PLTL with DSGLs. As a result, the SMDL pattern is also demonstrated useful to suppress the near-end crosstalk (NEXT) between the adjacent second-level curves, which in turn reduce the fluctuations in the group delay. In addition, the PLTL SMDL with DSGLs consequently have the superiority of suppressing the NEXT and FEXT simultaneously. Further simulations and measurements indicate that the performances of the PLTL SMDL with DSGLs lines are superior to the conventional method in a UWB range of dc to 25 GHz, including amplitude and group delay flatness, along with high time delay efficiency due to the slow wave property.