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This paper proposed a kind of guard traces based on a subwavelength periodic structure to reduce the far-end crosstalk (FEXT) of parallel microstrip lines in the PCB. This technology can be used to improve the false triggering and signal transmitting capacity of a multiconductor transmission line circuit system. In order to explore the present novel guard trace effect on isolating electromagnetic interference (EMI), the frequency response of the mutual capacitance and mutual inductance of the overall circuit system was provided and an equivalent circuit model was built. In comparison to the conventional microstrip line for isolating the EMI between parallel microstrip lines, the novel guard trace can efficiently reduce the mutual capacitance and mutual inductance of the overall circuit system. Thus, it is favorable for suppressing the crosstalk between microstrip lines. The $S$ -parameters calculation result showed that this kind of subwavelength periodic microstrip guard trace can isolate the EMI between two microstrip lines more effectively. Particularly, the conventional grounded guard trace needs a lot of dense grounded holes, which severely influences the wiring design of various layers of a multilayer circuit board. However, the proposed guard trace requires only one grounded hole, which has little influence on the circuit wiring of each layer of a multilayer printed circuit board. In our experiment, the step function signal of 30 ps rise time was imported into one microstrip line to measure the FEXT of the other microstrip line. It was demonstrated by the measurement result that the subwavelength periodic microstrip guard trace can reduce the FEXT to be below 5% of the transmission signal amplitude and is more flexible in practice. In compliance with the actual demand for a high-speed circuit, three isolation structures were proposed, and their isolation effects on the electromagnetic coupling between microstrip lines were verified individually.

Wireless communication have progressed so fast in recent years with the increased frequency of operation, faster signal speed, reduced feature size and increased the integration of analog and digital blocks within a constrained space. These made the signal integrity analysis is a challengine task to printed circuit board designers. The signal integrity effects need to be mitigated by the proper design of high speed interconnects. In order to reduce crosstalk and crosstalk induced jitter in high speed parallel links to DRAM interface, a novel parallel microstriplines with U shaped guard trace interconnect structure is proposed. The crosstalk performance of the proposed interconnect structure, it can be implemented in DRAM board and compared with the conventional guard intervening scheme. The proposed structure increased the maximum data rate from 800 Mbps to 3.3 Gbps and reduced CIJ more than 2 ps. [ABSTRACT FROM AUTHOR]

In this work, a new design approach for realizing printed circuit board (PCB) trace configuration with continuous impedance perturbation to reduce crosstalk in PCB interconnects is investigated. The purpose is to reduce far-end crosstalk without incorporating additional PCB components in order to modify the reactive couplings between the adjacent traces, however at the expense of the available frequency band. This is achieved by replacing a uniform victim trace on a PCB with a continuously varying-impedance trace that exhibits a lowpass filter frequency characteristic. A simplified design approach of the proposed trace impedance profile which is governed by a truncated fourier series is presented. The proposed trace shows better crosstalk reduction results compared to conventional intervening guard trace schemes. Several configurations were designed, implemented, and tested to demonstrate the advantages of the underlying principle. [ABSTRACT FROM AUTHOR]

This paper investigates how crosstalk coupling noise is generated in coupled striplines with inserted guard traces with different trace spacings. Design guidelines for reducing noise and the implemented noise reduction scheme, involving an additional grounding via on the guard trace, are proposed. A graphical method that is based on wave tracing is presented to illustrate the generation of crosstalk noise on the guard trace and the victim line. The results of simulations in the time and frequency domains, performed using HSPICE and the 3-D full-wave simulator high frequency structure simulator, are presented to elucidate the noise coupling. The 3-D full-wave simulator, computer simulation technology, is utilized to validate the time-domain simulation results. Approximate formulas for the amplitude of the induced crosstalk noise are presented. The magnitude of the time-domain crosstalk noise on the victim line is reduced by more than 70% using the reduction scheme with the additional grounding via. Moreover, in the frequency domain, the reduction of the magnitude of the first resonant crosstalk peak at approximately 1 GHz is over 25 and 35 dB for crosstalk noise at the near end and the far end, respectively. The maximum reduction of the measured common-mode current that is generated by the different trace spacings in the attached I/O cable exceeds 35 dB at the first resonant frequency. Finally, the frequency-domain measurements of crosstalk noise support the proposed analyses. [ABSTRACT FROM AUTHOR]

This paper proposes design schemes to reduce the common mode noise from weakly coupled differential serpentine delay microstrip lines (DSDMLs). The proposed approach is twofold: we leverage strongly coupled vertical-turn-coupled traces (VTCTs) instead of weakly coupled VTCTs (conventional pattern) and add guard traces. Time-and frequency-domain analyses of the proposed schemes for reducing the common-mode noise are performed by studying the transmission waveform and the differential-to-common mode conversion using the circuit solver HSPICE and the 3-D full-wave simulator HFSS, respectively. Compared to the conventional design of the weakly coupled DSDMLs, the proposed solutions yield a reduction of about 54% of the peak-to-peak amplitude of the common-mode noise, while the differential impedance remains matched along the complete length of the DSDML. Moreover, the range of frequencies, over which the magnitude of the differential-to-common mode conversion is now significantly reduced, is very wide, i.e., about 0.3–10 GHz. Furthermore, the differential insertion and reflection loss introduced by the newly proposed designs are almost the same as the ones achieved by using the conventional design. Finally, a favorable comparison between simulated and measured results confirms the excellent common-mode noise reduction performance of the proposed schemes. [ABSTRACT FROM AUTHOR]

Grounded guard traces are increasingly utilized to mitigate crosstalk noise interference in printed circuit boards or packages. This paper discusses how the coupled striplines inserted guard trace with an open-stub affects the crosstalk noise. The guard trace with an open-stub, also called guard trace stub, seriously degrades the performance of the coupled striplines with respect to signal integrity, and the extra crosstalk noise occurs both at near- end and far-end for stripline structure. In addition, an analytical formula is proposed to approximate the maximum magnitude of extra crosstalk noise that is caused by a guard trace stub. To maintain the crosstalk noise induced by the active line and extra crosstalk noise induced by the guard trace stub on the victim line with equivalent amplitude is proposed to obtain the best design for maximum reduction ratio of crosstalk noise at both the near-and far-end. Based on the proposed method, a design curve for the geometric structures of coupled striplines inserted guard trace stub is constructed. Using the design curve, a maximum reduced ratio of crosstalk noise for coupled striplines inserted guard trace stub can be selected. Narrowing trace width of the guard trace stub is proposed to eliminate the crosstalk noise. The maximum reduction in crosstalk noise in the presented examples exceeded 50% in this paper. Finally, a favorable comparison between the time-domain simulation and measured results validates the proposed concept and analysis approach. [ABSTRACT FROM PUBLISHER]

This paper investigates the utilization of the guard traces to improve the eye opening and jitter for serpentine delay lines. It is found that the guard trace can reduce the original time-domain transmission (TDT) and time-domain reflection (TDR) crosstalk noises by more than 50%, if shorted by only two grounded vias at both ends of the trace. The time domain analysis as well as the associated simple circuit modeling is presented to explain the occurrence of noise cancellation mechanism on the guard trace. In addition, narrow signal trace is proposed to improve the TDR waveform by compensating the impedance mismatch due to the inserted guard traces. Finally, the HSPICE simulation and time-domain measurements of crosstalk noises, TDR/TDT waveforms, and eye diagrams are performed to validate the proposed analysis and design. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, the problem of using guard traces for reducing crosstalk between differential transmission line pairs is investigated, both experimentally and by full-wave electromagnetic (EM) simulations. Different cases of differential lines crosstalk are treated with and without guard trace separation between the differential line pairs. Coated microstrip printed circuit board test structures including thru-reflect-line calibration standards are designed and fabricated on a high frequency laminate material, allowing direct measurement of crosstalk between adjacent differential line pairs in the absence and in the presence of guard traces stitched with vias of regular spacing. The test structures are characterized with mixed-mode scattering parameters using a physical layer test system. Different configurations (of differential line pairs) without guard trace, with floating guard traces (which are terminated and nonterminated) and with a solid guard trace separation are investigated using a High Frequency Structure Simulator (a commercial full-wave 3-D EM simulation tool). The experimental data are compared with the simulation results, and some conclusions and guidelines on the effect of guard traces for alleviating crosstalk between differential transmission lines are presented. [ABSTRACT FROM AUTHOR]