Expression of Concern: Predicting the Performance of Low-Loss On-Chip Inductors Realized Using Carbon Nanotube Bundles

Within the analog realm, integrated inductors continue to limit the performance of mixed-signal systems. To improve the performance of integrated inductors for future mixed-signal systems, alternative technologies must be investigated. In this paper, we propose low-loss on-chip inductors leveraging single-walled carbon nanotube (SWCNT) bundles, which have the potential to provide conductors with significantly lower resistivity than traditional copper technology. We develop a model for high-frequency current redistribution in SWCNT bundles, which we find can have a large effect on the resistance and quality factor of nanotube-based inductors. Leveraging a compact $RLC$ circuit model, we examine the potential quality factor improvement provided by nanotube-based inductors over copper-based inductors for mixed-signal circuit applications. The results indicate that the optimized SWCNT bundle-based inductors can potentially provide a significant increase in quality factor. To demonstrate the performance advantages of optimized nanotube-based inductors, we find that their increased quality factors can lead to a noise figure and power consumption improvement in low-noise amplifiers, which are critical radio frequency circuits in integrated wireless receivers. If the integrated circuit fabrication challenges associated with high-density nanotube-based wires can be overcome, nanotube-based inductors could enable future mixed-signal and wireless systems with greater performance.