Enhanced Microstrip Guard Trace for Ringing Noise Suppression Using a Dielectric Superstrate

Grounded guard traces are increasingly used to reduce the coupling-induced crosstalk, but the incurred ringing noise will strongly limit the performance for the microstrip structures. This paper describes the generation mechanism of the ringing noise and derives an analytical formula of the noise magnitude. Besides, an enhanced microstrip guard trace design is proposed to eliminate the ringing noise by covering the original microstrip structure with a superstrate of higher permittivity. A design space versus the superstrate thickness and the dielectric constant are constructed and in which, the guard trace needs be grounded at the two ends only without causing any ringing noise. Finally, the time-domain simulations and experiments are performed to verify the proposed concept.