Manodipan Sahoo

Modeling and Analysis of Crosstalk Induced Effects in Multiwalled Carbon Nanotube Bundle Interconnects: An ABCD Parameter-Based Approach

In this paper, the crosstalk effects in both small and large diameter multiwalled carbon nanotube bundle interconnects (MWCNTs) for the future nanoscale integrated circuits are studied with the help of ABCD parameter matrix approach for global levels of interconnects at 22- and 14-nm technology nodes. Here, isolated MWCNTs are modeled using an equivalent single conductor transmission line. The simulation results show that the results are at par with the result of SPICE model. It is observed that performance wise, the large diameter MWCNT bundles are better than both small diameter MWCNT bundles and copper wire for both repeated and unrepeated interconnects. The same trend is observed with the number of inserted repeaters. For repeated wires, the optimized placement of repeaters offsets the delay advantage numbers of MWCNT bundles over copper wire. Technology scaling adversely impacts the delay advantage numbers of small diameter MWCNT bundles. As far as the worst-case crosstalk noise peak voltage is concerned, the large diameter MWCNT bundles also outperform both small diameter MWCNT bundles and copper wire for longer interconnects. However, for shorter interconnects, copper wire and small diameter bundles outclass the large diameter bundles due to their relatively larger time constant. We have compared our crosstalk analysis results with the earlier work to justify the validity of our proposed model and observed that the results with our model are in well conformity with the existing work. It is seen that even the tall Cu vias are not going to significantly affect the performance of MWCNT bundle interconnects. Twice the minimum width global level interconnects are the optimal choice to achieve the maximum delay advantage using MWCNT bundle interconnects in comparison with Cu-based interconnects. Finally, our analysis shows that from the performance and signal integrity perspective, the large diameter MWCNT bundles are a suitable alternative to both small diameter MWCNT bundles and copper interconnects for future integrated circuit technology generations.

An ABCD parameter-based modeling and analysis of crosstalk induced effects in single-walled carbon nanotube bundle interconnects

Single-walled carbon nanotubes (SWCNTs) have the potential to revolutionize the interconnects in future nanoscale integrated circuits. In the proposed work, crosstalk effects are investigated in SWCNTs at 21 nm and 15 nm technology nodes for intermediate as well as global interconnects. An ABCD parameter based approach has been used to investigate crosstalk delay and noise in both sparse as well as dense SWCNT bundled interconnect system. It is evident from the simulation results that the proposed model is not only 100% accurate but also almost 10 times faster than SPICE. The worst case crosstalk induced delay and peak crosstalk noise voltages for SWCNT bundle interconnects are compared to those of conventional copper (Cu) interconnects at the intermediate as well as global level interconnects. Simulation results also confirm that dense SWCNTs are always ahead of sparse SWCNTs with respect to performance advantage numbers over copper for every levels of interconnects and irrespective of technology nodes. As far as the worst case peak crosstalk noise is concerned, there is a critical length after which the performance of the dense SWCNT bundles is better than that of its sparse counterpart. Proposed model, analysis, along with supportive simulation results prove that dense SWCNT bundled interconnect is one of the most promising alterative interconnect solution for future generation of nanoscale circuits compared to copper with respect to performance as well as signal integrity issues.

Performance analysis of multiwalled carbon nanotube bundles

In this work, we have presented a comprehensive analysis of the performances of Copper wire and MWCNT (Multi-walled Carbon Nano Tube) bundles across deep submicron technology nodes like 45nm, 32nm, 22nm and 16nm. The analysis has been done for local, intermediate and global level interconnects. The analytical closed form delay expressions for both the Copper wire and MWCNT bundles have been found out. It is observed that MWCNT bundles show better performance over Copper wire at all level of interconnects and technology nodes. In 16 nm technology node, the performance advantage numbers of MWCNT bundle over Copper wire are 50%, 90% and 85% for 20-μm long local interconnect, 200-μm long intermediate interconnect and 10000-μm long global interconnect respectively. It is also observed that performance numbers improve with scaling for all level of interconnects and the ratio of delay of MWCNT bundles and Copper wire for various level of interconnects agree well with the existing work.

An ABCD Parameter Based Modeling and Analysis of Crosstalk Induced Effects in Multiwalled Carbon Nanotube Bundle Interconnects

Cross talk effects in large diameter Multiwalled Carbon Nanotube bundle interconnects (MWCNTs) for the future nanoscale integrated circuits are investigated with the help of ABCD parameter matrix approach for intermediate and global interconnects at 22 nm and 14 nm technology nodes. Here, isolated MWCNTs are modeled using an equivalent single conductor transmission line. Simulation results show that the proposed model matches very well with the SPICE model available in literatures. The worst case cross talk induced delay and peak cross talk noise voltages for MWCNT bundle interconnects are derived and compared to those of conventional copper interconnects. The worst case cross talk delays for MWCNT bundle interconnects are less than 15% of that of copper interconnects for 1 mm long intermediate and less than 20% of that of copper interconnects for 2 mm long global interconnects for both the technology nodes. The ratio of peak cross talk noise voltage of MWCNT bundles to that of Copper is seen to decrease in scaled technology. We have compared our cross talk analysis results with the earlier work to verify the validity of our proposed model and observed that the results with our model are in good agreement with the existing work. Finally, our analysis shows that from the signal integrity perspective, large diameter MWCNT bundles are a very good alternative to copper interconnects for future Integrated circuit technology generations.

Modeling of Crosstalk Induced Effects in Copper-Based Nanointerconnects: An ABCD Parameter Matrix-Based Approach

Aggressive miniaturization has led to severe performance and signal integrity issues in copper-based interconnects in the nanometric regime. As a consequence, development of a proper analytical model for such interconnects is extremely important. In this work, an ABCD parameter matrix-based model is presented for fast and accurate estimation of crosstalk delay and noise for identically coupled copper-based nanointerconnect systems. Using the proposed model, the crosstalk delay and noise are estimated in copper based nanointerconnects for intermediate and global interconnects at the future integrated circuit technology nodes of 21 and 15 nm, respectively. Proposed model has been compared with SPICE and it is found that this model is almost 100% accurate as SPICE with respect to both the crosstalk delay as well as noise. Moreover, this model is as much as ~ 63 and ~ 155 times faster, respectively. From the crosstalk delay and noise analysis of unrepeated interconnects, it is observed that both delay and noise contribution will increase in scaled technology nodes. The same trend is observed also for the repeated interconnects. Also more number of repeaters and higher repeater sizes will be needed for delay minimization as we scale deeper. So as far as crosstalk induced effects are concerned, the copper interconnects will face a huge challenge to overcome in nanometer technology nodes.

An ABCD parameter based modeling and analysis of crosstalk induced effects in Multilayer Graphene Nano Ribbon interconnects

Crosstalk effects in Multilayer Graphene Nano Ribbon interconnects (GNRs) are investigated with the help of ABCD parameter matrix approach for intermediate and global level interconnects at 11 nm technology node. For long intermediate and global levels of interconnects, the worst case crosstalk delays for perfectly specular, doped multilayer GNR interconnects are far lesser than that of copper interconnects. Though neutral GNR interconnects introduce lesser worst case peak crosstalk noise voltage, it contributes more noise than its doped counterpart. Perfectly specular, doped multilayer zigzag GNR interconnects prove to be a suitable alternative to copper interconnects for future Integrated circuit.

Efficient and Compact Electrical Modeling of Multi Walled Carbon Nanotube Interconnects

Multi Walled Carbon Nano Tubes (MWCNTs) have received a lot of attention in recent years as an alternative to copper based interconnects due to its highly metallic nature. In this work, we develop a compact and efficient electrical model of MWCNT in the footsteps of equivalent electrical model of Single Walled Carbon Nanotubes (SWCNTs). Elmore delay based estimation methods are used to derive the performance numbers for MWCNT bundles. The proposed model is compared with SPICE and it is found that the proposed model is almost 100% accurate as SPICE.

Analysis of Crosstalk-Induced Effects in Multilayer Graphene Nanoribbon Interconnects

Crosstalk effects in multilayer graphene nanoribbon (GNR) interconnects for the future nanoscale integrated circuits are investigated with the help of ABCD parameter matrix approach for intermediate- and global-level interconnects at 11nm and 8nm technology nodes. The worst-case crosstalk-induced delay and peak crosstalk noise voltages are derived for both neutral and doped zigzag GNR interconnects and compared to those of conventional copper interconnects. The worst-case crosstalk delays for perfectly specular, doped multilayer GNR interconnects are less than 4% of that of copper interconnects for 1mm long intermediate interconnects and less than 7% of that of copper interconnects for 5mm long global interconnects at 8nm node. As far as the worst-case peak crosstalk noise voltage is concerned, neutral GNR interconnects are slightly better performing than their doped counterparts. But from the perspective of overall noise contribution, doped GNR interconnects outperform neutral ones for all the cases. Fin...

A 45 uW 13 pJ/conv-step 7.4-ENOB 40 kS/s SAR ADC for digital microfluidic biochip applications

In recent years Digital Micro-fluidic Bio-chips have become a suitable choice for point of care diagnostics. These devices can detect various properties of human blood by means of an optical detection technique. The data acquisition is generally done using a LED-photodiode setup working in conjunction with the biochip. The voltage signal obtained at the photodiode output needs to be converted into digital data for further processing. A low power 8 bit SAR ADC is designed for this purpose and implemented in UMC 180 nm technology. The functionality testing of the ADC is done using Spectre simulator of Cadence Analog Design Environment. The ADC consumes about 45 μWof power at 13 pJ/conv-step from a 1.8 V supply at 40 kS/s and achieves a SNDR of 46.5 dB, ENOB of 7.4 bits at a signal bandwidth of 10kHz. Mismatch analysis has been done by a set of Monte Carlo Simulations in Cadence. Even in worst case condition with 5% capacitance mismatch, the ADC achieves a SNDR of 43 dB, ENOB of 7 bits without any missing code.

Impact of Inductance on the Performance of Single Walled Carbon Nanotube Bundle Interconnects

In this work, we have studied the inductive properties of interconnects built with Single Walled Carbon Nan tube (SWCNT) bundle. We have used the most recent ITRS-2011 data while estimating the RLC parameters of SWCNT bundle interconnects. In our analysis, we have used the classical ABCD-parameter-matrix based method and a delay allowance of 50%. Simulations are performed for both sparse and dense SWCNT bundle interconnects at 21 nm and 15 nm technology nodes, considering three levels of their application: local, intermediate, and global. It is observed that for a 100 MHz periodic square wave input with a rise time of 10 ps, SWCNT bundle interconnects are not impacted by inductance. It is shown that for the given input signal and SWCNT bundle parameters, the length over which the inductive effects will be more prominent, has little practical significance. It is quantitatively shown that the inductive effects will mostly impact the long-intermediate and global interconnects. With technology scaling, such effects may worsen the performance. It is also observed that the Elmore-based methodology for delay estimation of SWCNT bundle interconnects predicts the actual delay very accurately with a maximum error of only 5.46%.