In future nanoscale integrated circuits, process technology scaling coupled with increasing operating frequencies will exacerbate the resistivity, electromigration, and delay problems that plague interconnect in today's designs. Metallic carbon nanotubes are a promising future replacement for on-chip copper interconnect due to their large conductivity and current carrying capabilities. In this research, we develop modeling and design techniques for carbon nanotube-based interconnect solutions. We create an equivalent RLC circuit model for individual and bundled single-walled and multi-walled carbon nanotubes, which we leverage to determine the optimal design for nanotube-based interconnect solutions. Using the proposed modeling and design techniques, we investigate the performance and reliability of nanotube-based structures in future mixed-signal VLSI applications including digital interconnect and passive components for analog integrated circuits. We also examine the nanotube properties and fabrication requirements necessary for nanotube-based interconnect to be a competitive solution compared to standard copper technology. The results indicate that nanotube-based interconnect solutions will have the potential to revolutionize the next generation of integrated circuits in mixed-signal VLSI applications.