The performance of coupled VLSI interconnects depends on their coupling capacitance and the dielectric medium surrounding them. However, the idea of designing the geometry of CNT bundles to optimize the coupling capacitance is not considered till now. So, in this paper, we model triangular CNT (T-CNT) bundles as VLSI interconnects, for the first time. Factors that reveal the performance of interconnects like propagation delay, crosstalk delay and power dissipated by the interconnects, are simulated in this paper. We do the performance analysis of T-CNT bundle interconnects and conventionally modeled square type CNT bundle interconnects. Upon comparison of the above said metrics, it was found that T-CNT bundle interconnects performed better.

Uma Sathyakam P

Department of Instrumentation

School of Electrical Engineering

Vellore Campus

Partha Sharathi Mallick

Ajay bisht

Yash tandon

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

2016 3rd International Conference on Emerging Electronics (ICEE)

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.

Fulltext

Journal of Circuits, Systems and Computers

Geometry-Based Crosstalk Reduction in CNT Interconnects

Triangular carbon nanotube (T-CNT) bundles are proposed as long interconnects for subthreshold VLSI circuits. The performance of subthreshold interconnects depends on the intrinsic quantum and electrostatic coupling capacitances of the interconnects. Proposed T-CNT bundles have the most optimum geometry that give least possible coupling capacitance between adjacent wires in an IC. First, we describe the T-CNT bundle models and of traditionally used square/rectangular CNT bundles for comparison. The subthreshold output current of an inverter is modelled, and hence, we find the optimum transistor widths for nFET and pFET that drives the subthreshold interconnects. This is carried out by the current-over-capacitance ratio approach, where the subthreshold current and the transistor output capacitance are considered. Then, we model the interconnects using equivalent single conductor models and find their propagation delay and power dissipated. The performance factors such as crosstalk-induced delay, power delay product and victim noise levels of capacitive coupled interconnects of T-CNT bundles are compared to traditionally used square/rectangular CNT bundles for lengths ranging from 500&nbsp;μm to 2000&nbsp;μm. We find that T-CNT bundles outperform square/rectangular CNT bundles.

Journal of Electronic Materials

Triangular Carbon Nanotube Bundle Interconnects for Subthreshold VLSI Circuits

Current mode signaling (CMS) is found to be advantageous than voltage mode signaling (VMS) in VLSI interconnects. So, we propose the use of triangular carbon nanotube bundles as VLSI interconnects for CMS in VLSI circuits. T-CNT bundles have inherent advantages of lesser propagation delay and crosstalk delay than traditionally proposed square CNT bundle interconnects. We analyze the propagation delays of both the types of bundles in voltage and current mode signalling schemes and compare the improvement of propagation delay in both the cases. We find that T-CNT bundles perform better than square bundles in both the signalling schemes. © 2019 IEEE.

2019 Innovations in Power and Advanced Computing Technologies (i-PACT)

Analysis of triangular CNT bundle interconnects for current mode signalling

This article presents a realistic inter-carbon nanotube (CNT) electrostatic coupling capacitance and tunnelling conductance model for a mixed CNT bundle. The change of potential across such a bundle necessitates the need to consider the inter-CNT capacitance in the equivalent circuit of CNT interconnects for very large scale integration circuits. The equivalent transmission line circuit model of a unit bundle containing one single-walled CNT (SWCNT) and one multi-walled CNT (MWCNT) has been shown. This new model is then used to calculate the delay induced by the inter-CNT capacitance and tunnelling conductance, which predicts the relative positioning of MW/SWCNTs in mixed CNT bundle.

International Journal of Electronics

Inter-CNT capacitance in mixed CNT bundle interconnects for VLSI circuits

Carbon nanotube based interconnect technology is becoming popular for its various merits over the current copper technology. The ability to conduct high current at high temperatures through the 1D structure is making the CNT interconnect technology an attractive one. Single wall and multi wall CNT interconnects have received greater interest initially when the mixed CNT bundles (MCBs) did not get much attention as VLSI interconnects. But, it was only in 2007 when the conductance study of mixed CNT bundles was done and since then many works have been reported. At this stage, it is essential to review the reports of MCB based interconnect technology. We present in this paper, the first review on MCB VLSI interconnects.

Nano Communication Networks

Towards realisation of mixed carbon nanotube bundles as VLSI interconnects: A review

Presented for the first time is an accurate modelling hierarchy for mixed CNT bundle interconnects. Single-walled CNTs and multi-walled CNTs have been modelled as equivalent single conductor transmission lines and then combined to form a mixed CNT bundle interconnect, which is basically a multiple equivalent single conductor model. Two multiple equivalent single conductor interconnects have been taken to form the multiconductor transmission line model. The delays from transient analysis for both models for a unit bundle have been compared with the corresponding ones for SWCNT bundles and MWCNTs that exist in the literature. It is found that mixed CNT bundle interconnects are superior to both SWCNT bundle and MWCNT interconnects in terms of delay.

Journal	Data powered by Typeset2016 3rd International Conference on Emerging Electronics (ICEE)
Publisher	Data powered by TypesetIEEE
Open Access	No