Interconnect Crosstalk Research Articles

Analysis of Crosstalk in GNR-Based Global Interconnects

Analysis of Crosstalk in GNR-Based Global Interconnects

A Neoteric Approach for Logic with Embedded Memory Leveraging Crosstalk Computing

One of the essential elements of computing is the memory element. Flip-flops form an integral part of a System-on-Chip (SoC) and consume most of the area on the die. To meet the high-speed performance demands by the data-intensive applications such as artificial intelligence, cloud computing, and machine learning, we propose to integrate memory with the logic to get built-in memory Logic circuits that operate based on the crosstalk computing logic. These circuits are called Crosstalk Built-in Memory Logic (CBML) circuits, which exploit the detrimental interconnect crosstalk and astutely turn this unwanted effect into a computing principle with embedded memory. By virtue of our novel CBML circuit technique, the logic is computed, and the result is stored intrinsically within these complex circuits. The stored values will be retained irrespective of the change in input until the next logic evaluation cycle. This neoteric embedding of memory in logic provides high-speed operation with a reduced number of transistors. In this article, we have manifested the built-in memory feature of the complex CBML circuits using 16 nanometer (nm) PTM models in HSPICE. Benchmarking is performed by comparing with the equivalent static CMOS circuits to compare the number of transistors, power, and performance. It is observed that the number of transistors consumed by CBML 4-bit Full-Adder (the key element prevalent in Arithmetic circuits, e.g., ALU, Counters) is up to 46% less, and performance is improved by 27% over the equivalent CMOS circuits. This circuit serves as an example of a large-scale CBML circuit. Also, the performance improvement achieved by other circuits such as 3-input AND and the CARRY logic is up to 60% along with a 40% reduction in the number of transistors. CBML circuits have the potential to pave the way for special high-speed macros with specifically engineered structures.

Analysis of Crosstalk in Coupled On-Chip VLSI Interconnects

Analysis of Crosstalk in Coupled On-Chip VLSI Interconnects

Sol–gel deposited xerogel, aerogel and porogen based porous low-k thin films: A comparative investigation

Low dielectric constant (Low-[Formula: see text]) films are used as inter layer dielectric (ILD) in nanoelectronic devices to reduce interconnect delay, crosstalk noise and power consumption. Tailoring capability of porous low-[Formula: see text] films attracted more attention. Present work investigates comparative study of xerogel, aerogel and porogen based porous low-[Formula: see text] films. Deposition of SiO2 and incorporation of less polar bonds in film matrix is confirmed using Fourier Transform Infra-Red Spectroscopy (FTIR). Refractive indices (RI) of xerogel, aerogel and porogen based low-[Formula: see text] films observed to be as low as 1.25, 1.19 and 1.14, respectively. Higher porosity percentage of 69.46% is observed for porogen-based films while for shrinked xerogel films, it is lowered to 45.47%. Porous structure of low-[Formula: see text] films has been validated by using Field Emission Scanning Electron Microscopy (FE-SEM). The pore diameters of porogen based annealed samples were in the range of 3.53–25.50 nm. The dielectric constant ([Formula: see text]) obtained from RI for xerogel, aerogel and porogen based films are 2.58, 2.20 and 1.88, respectively.

Temperature-Dependent Circuit Modeling and Performance Evaluation Due to Crosstalk in Capacitively Coupled Interconnects of Intercalation-Doped Multilayer Graphene Nanoribbon

The present work explores the temperature-dependent performance evaluation due to crosstalk in coupled interconnects of intercalation-doped multilayer graphene nanoribbons (ID-MLGNR). A temperature-dependent equivalent single conductor (ESC) model of arsenic pentafluoride (AsF5) ID-MLGNR is considered and is employed to analyze its crosstalk performance (i.e., crosstalk-induced noise and crosstalk-induced delay). Other metallic interconnect materials viz. mixed carbon nanotube bundles (MCB) and copper (Cu) are also analyzed in a similar manner. The temperature-dependent crosstalk performance of ID-MLGNR is compared with that of MCB and Cu, at different temperatures from 300 to 500 K. For the specified temperature range, in case of crosstalk-induced noise, the AsF5 ID-MLGNR-based long interconnects demonstrate superior performance to its MCBs and Cu counterparts. Moreover, the temperature-dependent crosstalk-induced delay is less with ID-MLGNR in comparison with both MCB and Cu interconnects. The large values of the mean free path (MFP) and conductivity of AsF5 ID-MLGNR contribute to its improved performance. In addition, the impact of variation in MFP, interlayer spacing and Fermi level is studied on the crosstalk delay performance of ID-MLGNR. From the obtained results, it is revealed that variation in these parameters results in the significant variation of 62 ps, 51 ps and 169 ps, respectively, in the odd mode (OM) crosstalk delay. Hence, for emerging nano-technology nodes (e.g., 14 nm), ID-MLGNR interconnects with its improved crosstalk performance are proposed as a potential alternative to its MCBs and Cu counterparts.

Temperature‐dependent analysis of crosstalk and delay uncertainty in multilayer graphene nanoribbon interconnects

SummaryIn this article, we have analyzed delay uncertainty due to crosstalk in multilayer graphene nanoribbon (MLGNR) interconnects. Crosstalk is a challenging problem in deep‐sub‐micron and nanometer designs. In this work, we have analyzed the crosstalk delay with a wide variation in chip operating temperature. The mean free path is modeled as a function of temperature. Furthermore, the resistance of MLGNR interconnect system is modeled. Crosstalk delay analysis is performed for both top‐contact MLGNR and side‐contact MLGNR (SC‐MLGNR) interconnects and compared the results with that of the traditional Cu interconnects. The analysis has been carried out for different interconnect widths 11, 16, and 22 nm and lengths 10, 50, and 100 μm for three different chip operating temperatures 233, 300, and 398K. The decrease in rise/fall delay (speed up) and increase in rise/fall time delay (slow down) are modeled. Finally, the delay uncertainty is modeled for different interconnect systems. The percentage change in delay values for speed up and slow down cases are −23.4%, −29.8% and 114.4%, 161.9%, respectively, for 10μm SC‐MLGNR interconnect. It is shown that the delay uncertainty is significantly less in SC‐MLGNR interconnects and with the advancement of technology the performance is improved as compared with copper interconnects.

Temperature-dependent crosstalk and frequency spectrum analyses in adjacent interconnects of a mixed CNT bundle

This paper presents temperature-dependent circuit modeling and performance analyses of single as well as capacitively coupled interconnects of a mixed CNT bundle (MCB) with consideration of the tunneling effect at temperatures from 300 to 500 K at the 14-nm technology node. Four possible MCB structures, viz. MCB-1, MCB-2, MCB-3, and MCB-4, are considered, and their results are compared with those for a copper-based interconnect at the same technology node. For the single line architecture, as the temperature is increased from 300 to 500 K, MCB-4 exhibits a shorter propagation delay in comparison with the other MCBs (1–3) and copper. The results of the frequency spectrum analysis reveal that MCB-4 exhibits a 17.70% wider bandwidth than its copper counterpart. Also, the bandwidth of MCB-4 decreases with increasing temperature, indicating greater signal loss at higher temperatures. For the coupled line architecture, considering different switching conditions of the aggressor and victim lines, MCB-4 exhibits a shorter average dynamic crosstalk-induced delay compared with the other MCBs (1–3) or copper. In comparison with the odd mode of switching, MCB-4 exhibits a 36.45% shorter crosstalk-induced delay with the even mode of switching when the temperature is varied from 300 to 500 K. Similarly, the functional crosstalk noise levels in terms of the overshoot, undershoot, rise glitch, and fall glitch are also found to be significantly lower for MCB-4 compared with the other MCBs (1–3) or copper. The results of the simulations further reveal that MCB-4 exhibits frequency noise components with 70.66% lower amplitude compared with copper, which means that MCB-4 filters more noise components than copper. Furthermore, the amplitude of the frequency noise components increases with rise in temperature.

Modal crosstalk in Silicon photonic multimode interconnects.

We investigate modal crosstalk in silicon photonic MDM-based interconnects using tapered multiplexers. Crosstalk from coherent optical interference originates from variation in the physical structure and alters the transmission link performance. Through simulations and experimental work, optical crosstalk as a function of wavelength is analyzed to understand its impact in MDM and MDM-WDM dual-multiplexing applications. The detrimental effects are validated in the frequency and time domains through fabricated MDM interconnects of various lengths. Results indicate modal crosstalk must be < -22 dB to maintain a BER of 10-12. The experimental methodology assesses the optical modal crosstalk's impact on the data, towards a mitigation approach to improve the payload signal integrity and enable system-level optimization such as channel wavelength allocation.

Geometry-Based Crosstalk Reduction in CNT Interconnects

This paper proposes novel triangular cross-sectioned geometry of carbon nanotube (CNT) bundles for crosstalk and delay reduction in CNT bundle interconnects for VLSI circuits. First, we formulate the equivalent single conductor (ESC) transmission line models of the interconnects. Through SPICE analysis of the ESC circuits, we find the propagation delays of the proposed CNT bundles. Next, we model the capacitively coupled interconnects for crosstalk analysis. It is found that the coupling capacitance of triangular CNT bundle is 29% lesser than the traditionally used square CNT bundles. Further, the crosstalk-induced delay of triangular interconnects is found to be 30% lesser when compared to square bundle interconnects. The reduction in delay is found to increase as the number of CNTs in the bundle increases. So, we suggest that triangular CNT bundles are the most suitable candidates as global interconnects.

An Efficient MRTD Model for the Analysis of Crosstalk in CMOS-Driven Coupled Cu Interconnects

An Efficient MRTD Model for the Analysis of Crosstalk in CMOS-Driven Coupled Cu Interconnects

Reducing Crosstalk Induced Delay and Peak Noise in Carbon Nanotube Interconnects

Background: Crosstalk will be a major concern in future nano ICs where the components will be scaled down to a few nanometers. In particular, modeling of CNT based interconnects shows that they will suffer from crosstalk when fabricated at smaller technology nodes. Objective: This paper presents reduction of crosstalk and noise in CNT bundle interconnects. We propose the use of small diameter semiconducting CNTs (s-CNTs) as electromagnetic interference (EMI) shields for CNT bundle interconnects. Methods: The coupling capacitance of the proposed CNT bundle structure shows that crosstalk can be reduced significantly by using small diameter s-CNTs. We perform SPICE analysis to show the reduction in crosstalk and peak noise. Results: The proposed bundle geometry reduces 46% crosstalk induced delay and 23% output peak noise as compared to conventional CNT interconnects. Conclusions: Small diameter semiconducting CNTs can be used as EMI shields to reduce crosstalk and noise in CNT interconnects.

A Novel Unified Model for Copper and MLGNR Interconnects Using Voltage- and Current-Mode Signaling Schemes

A novel unified model, for conventional copper and futuristic multilayer graphene nanoribbon (MLGNR) interconnects, based on a finite-difference time-domain (FDTD) technique has been proposed in this paper. The performance of quasi-transverse electromagnetic model of interconnects has been exhaustively analyzed for both voltage-mode signaling (VMS) and current-mode signaling (CMS) schemes. The effect of variations in edge roughness and dopant dependent Fermi energy in MLGNR interconnects has been examined. The crosstalk and coupling effects in interconnects have been investigated by incorporating capacitive and inductive interconnect parasitic elements. From the results carried out for 32-nm technology node, it has been observed that for similar dimensions and operating conditions, MLGNR interconnects show a significant performance improvement over the copper interconnects. The results also show that the CMS scheme outperforms VMS scheme at global wire lengths and is very suitable for state-of-the-art chip applications. The proposed model results are in close propinquity with the SPICE results. Furthermore, the FDTD-based model is computationally efficient compared to SPICE.

The Beauty of Symmetry: Common-Mode Rejection Filters for High-Speed Interconnects and Band Microwave Circuits

Common-mode rejection filters operating at microwave frequencies have been the subject of intensive research activity over the last decade. These filters are of interest for the suppression of common-mode noise in high-speed digital circuits, where differential signals are widely employed due to the high immunity to noise, electromagnetic (EM) interference, and crosstalk of differential-mode interconnects. These filters can also be used to improve common-mode rejection in microwave filters and circuits dealing with differential signals. Ideally, common-mode stopband filters should be transparent for the differential mode from dc up to very high frequencies (all pass), preserve the signal integrity for such mode, and exhibit the widest and deepest possible rejection band for the common mode in the region of interest. Moreover, these characteristics should be achieved by means of structures with the smallest possible size.

Crosstalk in Free Space Optical Interconnects that Use Micro-Lenses Arrays: Practical Consideration

The effect of positive spherical aberration of micro-lens on the optical crosstalk in free space optical interconnects is considered. Using the derived field distribution at the detector array, the optical crosstalk level is evaluated and numerical results are provided. It is found that practical lenses with positive spherical aberration increases the crosstalk and degrade the system performance.

Compact Physical Model for Crosstalk in Spin-Wave Interconnects

We propose a formalism of a compact physical model for crosstalk noise analysis between two coplanar backward volume spin-wave interconnects. Comparing the amplitudes of the signal in the active line and the noise in the victim line, we introduce a figure of merit for crosstalk—the longitudinal or line-to-line coupling. It is shown that the crosstalk becomes prohibitively high as the edge-to-edge spacing between the lines goes down, and thus putting a limitation on the routing and placement in a spin-wave bus network. The position of the peak crosstalk noise coupling for different spacings and frequencies of excitation reveals a new limitation to the maximum interconnect length. Furthermore, the technique of superposition analogous to $RLC$ interconnects is exploited to explain the complicated nature of crosstalk noise and develop a mechanism for modeling crosstalk. Finally, a compact physical model is derived using analytical expressions, which demonstrate a reasonably good agreement with the actual full micromagnetic simulation results.

Crosstalk Analysis of Current-Mode Signalling-Coupled RLC Interconnects Using FDTD Technique

ABSTRACTIn nanometre regimes, interconnect crosstalk noise has serious implications as it affects the signal integrity of the system. An accurate analysis of crosstalk effects is very essential and a critical issue. This paper efficiently models and analyses the crosstalk effects in current-mode signalling (CMS) multiline-coupled-distributed resistance-inductance-capacitance (RLC) interconnects. The interconnects are driven by complementary metal-oxide-semiconductor (CMOS) gates. The non-linear behaviour of metal-oxide-semiconductor (MOS) transistors in CMOS gate is characterized by an nth power law model. Both inductive and capacitive couplings have been considered to incorporate coupling effects in interconnects. The model is formulated using a finite-difference time-domain (FDTD) technique. The functional and dynamic crosstalk effects have been analysed for different interconnect lengths and varying transition time for the first time in CMS interconnects. The efficacy of CMS interconnects is evaluated by comparison with the conventional voltage-mode signalling (VMS) interconnects. It is analysed that CMS interconnects have lesser crosstalk-induced delay than VMS interconnects. Also, normalized undershoot voltage in CMS interconnects is lesser as compared to VMS signalling interconnects. The results are validated using simulation program with integrated circuit emphasis simulations. The analyses have been carried out for 32 nm technology node.

Statistical Interconnect Crosstalk Noise Model and Analysis for Process Variations

When operating frequency is over several gigahertz, the effect of inductance plays an important role and should be included for accurate and speed crosstalk noise analysis. And for new generation IC (Integrated circuit) design tools, the crosstalk noise analysis tools should consider the influence of process variations. In this paper, we propose coupled RLC crosstalk noise distributed parameter model with capacitive load termination. And we develop the framework that how to use the crosstalk noise model for process variations. Our results show that compare with HSPICE, the critical data errors of proposed model are within 1% and the relative errors occurred between calculated values for process variations and HSPICE Monte Carlo simulation values are less than 5%. The key features of the new model include: (1) The impact of inductance on crosstalk noise is considered; (2) The model can be used for process variations analysis; (3) The model reflect the effects of load capacitance directly; (4) The numerical inversion of Laplace transform is introduced for improving speed. So the proposed model meets the needs of future IC design both in speed and accuracy.

Precise Crosstalk Assessment in Complex Nanointerconnects via a Family of Unconditionally-Stable Nonstandard Time-Domain Algorithms

A class of nonstandard locally one-dimensional finite-difference time-domain schemes is developed in this paper for the accurate characterization of crosstalk and intermodulation distortions in complicated nanostructured interconnects. The novel 3-D methodology introduces a general curvilinear discretization to consistently treat the rapidly varying frequency-dependent behavior of these lossy materials. In this way, the resulting high-order forms minimize the artificial dispersion and dissipation errors of usual approaches and guarantee the unconditional stability of far shorter simulations. Numerical results, compared with measurement data, verify the assets of the proposed technique via the study of various fabric/epoxy devices with nanocomposite media.

An Efficient Methodology for Estimating Interconnect Crosstalk Noise in Deep-Submicron Technologies

To solve the crosstalk noise question in deep-submicron technologies, an efficient methodology for estimating interconnect crosstalk noise is proposed in this paper. PCA and ICA techniques are applied to reduce correlations of process variations, and moment matching scheme is used to obtain the PDF of crosstalk noise in victim coupled with multiple aggressors. Experimental results show that our method maintains the efficiency of past approaches, and significantly improves on their accuracy.

Non-uniform PCB traces with prescribed frequency bands for improved crosstalk immunity

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.