Interconnect Challenges and Carbon Nanotube as Interconnect in Nano VLSI Circuits

This chapter discusses about the behavior of Carbon Nanotube (CNT) different structures which can be used as interconnect in Very Large Scale (VLSI) circuits in nanoscale regime. Also interconnect challenges in VLSI circuits which lead to use CNT as interconnect instead of Cu, is reviewed. CNTs are classified into three main types including Single-walled Carbon Nanotube (SWCNT), CNT Bundle, and Multi-walled Carbon Nanotube (MWCNT). Because of extremely high quantum resistance of a SWCNT which is about 6.45 kΩ, rope or bundle of CNTs are used which consist of parallel CNTs in order to overcome the high delay time due to the high intrinsic (quantum) resistance. Also MWCNTs which consist of parallel shells, present much less delay time with respect to SWCNTs, for the application as interconnects. In this chapter, first a short discussion about interconnect challenges in VLSI circuits is presented. Then the repeater insertion technique for the delay reduction in the global interconnects will be studied. After that, the parameters and circuit model of a CNT will be discussed. Then a brief review about the different structures of CNT interconnects including CNT bundle and MWCNT will be presented. At the continuation, the time domain behavior of a CNT bundle interconnect in a driver-CNT bundle-load configuration will be discussed and analyzed. In this analysis, CNT bundle is modeled as a transmission line circuit model. At the end, a brief study of stability analysis in CNT interconnects will be presented

4 Bit Comparator Design Based on Reversible Logic Gates

Abstract-Today, reversible logic circuits has attracted considerable attention in improving some fields like nanotechnology, quantum computing, and low power design. In this paper 4 bit reversible comparator based on classical logic circuit is represented which uses existing reversible gates. In this design we try to reduce optimization parameters like number of constant inputs, garbage outputs, and quantum cost. The results show that, the proposed comparator has 4 quantum cost and one constant input less than the prior design

A novel ultra low-energy sub-threshold inverter based on nanoscale Field Effect Diode

A novel sub-threshold inverter based on nanoscale Field Effect Diode (FED) and a basic static CMOS inverter are investigated in this paper. Simulation results demonstrate that power consumption and Power Delay Product (PDP) of the sub-threshold inverter which is designed with nanoscale FED are 57.9% and 18.21% less than these factors in a comparable CMOS sub-threshold inverter. So the nanoscale FED scheme can provide better power efficiency than standard sub-threshold CMOS inverters