Crosstalk bandwidth and stability analysis in graphene nanoribbon interconnects

Based on transmission line modeling (TLM), and using the Nichols chart, we present a bandwidth and stability analysis, together with step time responses, for coupled multilayer graphene nanoribbon (MLGNR) interconnects that is inquired for the first time. In this analysis, the dependence of the degree of crosstalk relative stability for coupled MLGNR interconnects comprising of both capacitive and mutual-inductive couplings between adjacent MLGNR has been acquired. The obtained results show that with increasing the length or decreasing the width of the MLGNRs, the stability in near-end output increases. While, any increase in the length or width of MLGNRs, decrease the stability of far-end output. Also, by increasing capacitive coupling or decreasing inductive coupling, the near-end output becomes more stable, and the far-end output becomes less stable. Moreover, any increase in the length or capacitive coupling, decreases the bandwidth, whereas any increase in the width or inductive coupling, increases the bandwidth. Finally, transient simulations with Advanced Design System (ADS) show that the model has an excellent accuracy.     

Far-end crosstalk reduction in double-layered dielectricinterconnects

The problem of far-end crosstalk reduction is considered. Various cases of far-end crosstalk reduction in single and cascaded sections of two coupled interconnects in a double-layered dielectric environment are investigated by computer modeling of capacitive and inductive couplings and by simulation of far-end crosstalk waveforms     

Transfer matrix model of multilayer graphene nanoribbon interconnects

A general, algorithmic and exact transfer matrix model is presented for multilayer graphene nanoribbon (MLGNR) interconnects that is based on multi transmission line method (MTLM). In the proposed transfer matrix formulation the effect of Fermi level shift in GNR layers is considered. Also the capacitive and inductive coupling between the GNR layers is regarded in this matrix model. Moreover, in order to get the precise results, the block number parameter for distributed property of the interconnects is proposed for the first time. The straightforward, general and algorithmic format of the proposed matrix model causes it to be used for different technology nodes and length of the interconnects. Moreover any variation in the physical parameters can be involved simply in this formulation. Using this matrix model, one can examine different analytical prospects such as Nyquist, Bode, and Nichols stability criteria, zero and poles and step time responses for on-chip MLGNR interconnects, implemented for integrated circuit applications. Also this matrix model can be used in circuit simulators such as HSPICE in order to simulate the VLSI-ULSI circuits. As the couple of examples, we have extracted Nyquist diagrams and step time responses for 10 nm, 14 nm, and 22 nm technology nodes. The results show that relative stability of MLGNR interconnects increases with increasing technology node and interconnect length. The results demonstrate a considerable difference between the responses obtained using traditional MLGNR interconnect formulation and the exact proposed matrix model.     

Sensitivity Analysis of Coupled Interconnects for RFIC Applications

This paper investigates the sensitivity of on-wafer coupled interconnects to the Si CMOS process parameters. Experiments are conducted to emulate state-of-the-art and future technologies. Some important parameters characterizing the coupled interconnects have been examined. The influence of the process parameters on transmission, reflection, near-end, and far-end crosstalk capacities of the coupled interconnects are discussed     

不需双端检测的声回波对消算法研究

声回波对消中双端对讲情况下的近端话音对自适应算法有很大影响。为避免双端话音检测,在滤波型LMS算法基础上,用远端信号和误差输出信号的和代替远端信号去激励预测误差滤波器,降低近端话音的影响。另为进一步提高算法抗近端干扰的能力,做了变步长的改进,首先将步长反比于输出信号预测误差的短时功率,其次将步长正比于预测误差的互相关系数。实验表明,文中提出的两算法在近端话音出现时表现出较好的性能,其中第二种有更好的稳态失调。     

高速数字电路PCB中串扰问题的研究与仿真

针对高速数字电路PCB中传输线间串扰的严重性,从精确分析PCB中串扰噪声的角度出发,在传统的双线耦合模型的基础上,采用了一种三线串扰耦合模型。该模型由两条攻击线和一条受害线组成,两条攻击线位于受害线的两侧,线间采取平行耦合的方式。利用信号完整性仿真软件Hyperlynx对受害线上的近端串扰噪声和远端串扰噪声进行了仿真。仿真结果表明,不同的传输模式和传输线类型、信号层与地平面的距离、耦合长度、传输线间距和信号上升/下降沿等因素会对受害线上的近端串扰和远端串扰产生较大的影响。在分析仿真结果的基础上,总结出了高速PCB设计中抑制串扰的有效措施,对高速数字电路设计有一定的指导意义。     

Measurements of crosstalk between closely-packed lossy microstrips on silicon substrates

The measured near-end and far-end crosstalks for closely-packed microstrips are reported. The near-end crosstalk is less than 10% and the far-end crosstalk is less than 5% (of the driven signal) between two microstrips with 10 mu m width and 10 mu m spacing, when the active line is driven by a fast step pulse with approximately 40 ps rise time. Based on their measurements, the authors believe that closely-packed lossy microstrips can be used for high speed digital signal transmission, without much concern of crosstalk.<>     

Proposal and analysis of relative stability in mixed CNT bundle for sub-threshold interconnects

We introduce a Nyquist stability analysis of coupled mixed CNT bundle (MCB) for sub-threshold interconnects. In this analysis, the dependence of relative stability of sub-threshold MCBs with specific and probabilistic distribution of CNTs, on the geometry and probability of metallic CNTs, has been obtained. Using the proposed ABCD model and Nyquist stability criterion for sub-threshold MCBs, we show that, by increasing the diameter of each individual CNT and the length of MCB, the sub-threshold MCB interconnect system becomes more stable, while a densely packed MCB reduces the relative stability. Moreover, the crosstalk impact results in the greater stability of sub-threshold MCB system in comparison to a single interconnect. The crosstalk delay of MCB and composite Cu-MWCNT interconnects is also compared at various lengths. This is, so far, the first instance that such an analysis has been presented for coupled sub-threshold MCB interconnects.     

Crosstalk Prediction of Single- and Double-Walled Carbon-Nanotube (SWCNT/DWCNT) Bundle Interconnects

The crosstalk effects in single- and double-walled carbon-nanotube (SWCNT and DWCNT) bundle-interconnect architectures are investigated in this paper. Some modified equivalent-circuit models are proposed for both SWCNT and DWCNT bundles, where capacitive couplings between adjacent bundles are incorporated. These circuit models are further used to predict the performance of SWCNT and DWCNT bundle interconnects in comparison with the Cu wire counterpart at all interconnect levels for advanced future technology generations. It is found that, compared with the SWCNT bundle, the DWCNT bundle interconnect can lead to a reduction of crosstalk-induced time delay, which will be more significant with increasing bundle length, while the peak voltage of the crosstalk-induced glitch in SWCNT and DWCNT bundle interconnects is in the same order as that of Cu wires. Due to the improvement in time delay, it is numerically confirmed that the DWCNT bundle interconnect will be more suitable for the next generation of interconnect technology as compared with the SWCNT bundle counterpart.      

A statistical approach to derive an electrical port model of capacitively coupled interconnects

This paper considers the derivation of an electrical model at the input/output ports of a generic system of nonparallel interconnects that can be employed to simulate cross talk and delay effects through a conventional SPICE-like simulator. Only capacitive coupling effects are considered. The equivalent model of the interconnects system is determined through an iterative procedure based on the contemporary adoption of the floating random walk method that estimates the grounding and coupling capacitances per unit length and the Picard-Carson procedure that determines the entries of the transmission-matrix (T-matrix) representation at the electrical ports. It is shown that the entries of the T matrix can be efficiently computed through Monte Carlo integration.     

A Serpentine Guard Trace to Reduce the Far-End Crosstalk Voltage and the Crosstalk Induced Timing Jitter of Parallel Microstrip Lines

A serpentine guard trace is proposed to reduce the peak far-end crosstalk voltage and the crosstalk induced timing jitter of parallel microstrip lines on printed circuit boards. The vertical sections of the serpentine guard increase the mutual capacitance without much changing the mutual inductance between the aggressor and victim lines. This reduces the difference between the capacitive and inductive couplings and hence the far-end crosstalk. Comparison with the no guard, the conventional guard, and the via-stitch guard shows that the serpentine guard gives the smallest values in both the peak far-end crosstalk voltage and the timing jitter. The time domain reflectometer (TDR) measurement shows that the peak far-end crosstalk voltage of serpentine guard is reduced to 44% of that of no guard. The eye diagram measurement of pseudo random binary sequence (PRBS) data shows that the timing jitter is also reduced to 40% of that of no guard.      

Multichannel signal processing for data communications in thepresence of crosstalk

Transceiver designs for multiple coupled channels typically treat the crosstalk between adjacent twisted pairs as random noise uncorrelated with the transmitted signal. The authors propose a transmitter/receiver pair that compensates for crosstalk by treating an entire bundle of twisted pairs as a single multi-input/multi-output channel with a (slowly varying) matrix transfer function. The proposed transceiver uses multichannel adaptive FIR filters to cancel near- and far-end crosstalk, and to pre- and postprocess the input/output of the channel. Linear pre- and postprocessors that minimize mean squared error between the received and transmitted signal in the presence of both near- and far-end crosstalk are derived. The performance of an adaptive near-end crosstalk canceller using the stochastic gradient (least-mean-square) transversal algorithm is illustrated by numerical simulation. Plots of mean squared error versus time and eye diagrams are presented, assuming a standard transmission line model for the channel. A signal design algorithm that maps a vector input bit stream to a stream of channel symbol vectors is also presented and illustrated explicitly for s simple model of two coupled channels     

Crosstalk fault modeling in defective pair of interconnects

The manufacturing defect in the interconnect lines can lead to various electrical faults, e.g. defect due to under-etching effect/conductive particle contamination on interconnect line can lead to increased coupling capacitances between the two adjacent interconnects, which, in turn, can eventually result in crosstalk fault in the deep sub-micron (DSM) chips. In this paper, we describe the line-defect-based crosstalk fault model that will be helpful in analyzing the severity of the defect/fault, as the crosstalk fault occasionally leads to various signal integrity losses, such as timing violation due to excessive signal delay or speed-up, logic failure due to crosstalk positive/negative glitch above/below logic low/high threshold and also reliability problem particularly due to crosstalk glitch above logic high threshold. Our crosstalk fault model is very fast (at least 11 times faster than PSPICE model) and its accuracy is very close to PSPICE simulation results when the defect/fault is located in the middle of interconnects, whereas for the defects located at the near-end/far-end side of aggressor-victim the model accuracy differs marginally.     

Fused taper/filter hybrid single-mode wavelength divisionmulti/demultiplexer

A low loss and low crosstalk single-mode wavelength division multi/demultiplexer was successfully fabricated by embedding an interference filter in each output arm of a fused taper coupler. The insertion loss was around 1.5 dB at the wavelengths of 1.3 μm and 1.55 μm, and both near-end and far-end crosstalks were less than -50 dB     

Reduction of Transient Far-End Crosstalk Voltage and Jitter in DIMM Connectors for DRAM Interface

The transient far-end crosstalk voltage and the crosstalk-induced jitter of dual in-line memory module (DIMM) connectors are reduced by about 80% by increasing the mutual capacitance between DIMM connector pins with the additional interdigitated-comb-shaped metal-stub patterns on the motherboard. It was confirmed by the far-end crosstalk voltage waveform measurements using TDR and the eye diagram measurements at the data rates of 15 Mbps, 100 Mbps, and 3 Gbps. This reduction technique can be applied to the connectors where the inductive coupling ratio is larger than the capacitive coupling ratio.     

Modeling and analysis of crosstalk induced overshoot/undershoot effects in multilayer graphene nanoribbon interconnects and its impact on gate oxide reliability

Crosstalk induced overshoot/undershoot effects in multilayer graphene nano ribbon interconnects (MLGNRs) are investigated with the help of ABCD parameter matrix approach for intermediate level interconnects at both 11 nm and 8 nm technology node. The worst case crosstalk induced peak overshoot voltage for perfectly specular, doped multilayer zigzag GNR interconnects is comparable to that of copper interconnects. The performance of neutral GNR interconnects is better than that of its doped counterpart with respect to peak crosstalk overshoot. But from the perspective of overall overshoot width and overshoot area contribution, perfectly specular, doped MLGNR interconnects outperform all other alternatives. As far as the effective electric field across the gate oxide is concerned, the doped MLGNR interconnects outperform neutral ones and copper interconnects for all the cases. It is estimated that the doped perfectly specular multilayer GNR interconnects have gate oxide failure rates (AFR) of ~ 240 × and ~ 790 × lesser than copper interconnects for 11 nm and 8 nm technology node respectively. So, from the gate oxide reliability perspective, perfectly specular, doped multilayer zigzag GNR interconnects are great advantageous to copper interconnects for the future integrated circuit technology generations.     

Active antenna array lumped ring configuration

Coupled active antenna oscillator arrays are used for power-combining at microwave and millimeter-wave frequencies. It is known that the relative phase determined by the element separation distance ultimately determines the array operational mode and, hence, far-field radiation characteristics. Separately, it is known that coupled oscillator modal stability is achieved by coupling oscillators through lumped capacitive elements. In this paper, an arrangement whereby lumped capacitive elements (placed across the oscillator loads) and radiative coupling are employed concurrently is investigated. The arrangement takes the form of a ring of coupled oscillators used to excite a 2×2 antenna array. The effect that these couplings have on array behavior are evaluated using time-domain analysis and analytically derived equations. Experimental results for far-field radiation patterns are discussed in relation to coupled oscillator dynamical behavior. These suggest that the theoretical predictions are valid, offering a robust design tool for studies of larger power-combining arrays     

衬底材料对微带线间串扰耦合的影响研究

随着系统频率的提高,衬底材料特性已成为影响信号走线之间串扰的一个不可忽略的因素。该文基于传输线方程和频域S参数对两平行微带线间串扰耦合进行理论分析,并结合全波3维电磁场仿真工具对具有不同介电常数和不同厚度的衬底材料进行了仿真和分析,得到了微带线在不同衬底下的电场分布,以及近端和远端串扰随频率、衬底介电常数和厚度变化的曲线。随着频率的增大,远端串扰将大于近端串扰,并且随着衬底介电常数和厚度的增加,微带线间的串扰呈现正弦上升的变化趋势。     

A Novel Approach for Stability Analysis in Carbon Nanotube Interconnects

This letter introduces a new method for stability analysis of carbon nanotube (CNT) interconnects based on transmission line modeling and using the Nyquist stability criterion for the first time. Using this new method, the degree of relative stability for CNT bundle interconnects, versus the length of bundle and the diameter of each individual CNT, has been obtained. The obtained results show that with increasing the length of the CNT bundle and the diameter of each individual CNT interconnect, the relative stability increases, and the system becomes more stable.      

Interconnection channel capacity under crosstalk noise

The channel capacity of a parallel bus structure was examined in relation to the ever increasing demand for signal input and output. The limitations on signal integrity caused by both far-end and near-end crosstalk noise were considered. Expressions for the signal waveforms were developed using a rudimentary model. The expressions were then used to evaluate the channel capacity for perfectly matched lines in the high-frequency regime where skin effect and dielectric loss dominate the loss due to the static resistance. The analysis showed that binary logic yields the maximum channel capacity. For the parameters assumed as an illustrative example, the input rise time needed to achieve the maximum channel capacity cannot be achieved with today's technology. For source rise times longer than this threshold or optimum rise time, the maximum channel capacity is achieved by using multilevel logic. In the case of short lines, insufficient coupling exists between lines to meet the channel capacity condition for two levels. Therefore, for short lines multiple logic also is necessary to achieve maximum channel capacity