Using CAD to Shape Experiments in Molecular QCA

Abstract

This paper examines how circuits and systems made from molecular QCA devices might function. Our design constraints are "chemically reasonable" in that we consider the characteristics and dimensions of devices and scaffoldings (circuit boards to attach devices to) that have actually been fabricated (currently in isolation). We will show that not only is the work presented here a necessary first step for any work in QCA CAD, but also that by considering issues related to design can actually help shape experiments in the physical sciences for emerging, nano-scale devices. Our work shows that circuits, scaffoldings, substrates, and devices must all be considered simultaneously. Otherwise, there is a very real possibility that the devices and scaffoldings that are eventually manufactured will result in devices that only work in isolation. This work is especially timely as experimentalists are currently working to merge the different experimental tracks -i.e. to selectively place a QCA device.

Nanomagnet logic: progress toward system-level integration

“…Similar functionality will also be needed as more complex NML circuits are designed and fabricated. However, existing work [45] has suggested that, for QCA-like architectures (that require nearest neighbor interactions) while theoretically possible, wire crossings like those illustrated in figure 9(a) can be more difficult to physically implement than in a CMOS equivalent. Given the experimental state of the art for most electrostatic implementations of QCA, any such crossing would seemingly need to be done in-plane.…”

Defects and faults in QCA-based PLAs

“…In QCA research, similar studies have been done. From reconfigurable designs ] and defect studies Ottavi et al 2005;Niemier et al 2006] up to fault modeling [Huang et al 2004;Crocker et al 2007] and this work on mapping, QCA is proving to be an exciting emerging technology with several implementation alternatives that target many applications.…”

“…Proper association of defects to faults helps in studying the fault probabilities and yield. By examining experimental data and performing simulations at the physical level Niemier et al 2006;Donahue and Porter], we have matched defects to faults for two QCA implementations. In Table I, we summarize the faults that are induced by five typical defect types, that is, shifts, rotations, missing, stray charges and misshapenness.…”

Performance and Energy Impact of Locally Controlled NML Circuits

“…-did not consider the overhead of clocking, which is required to drive any QCA-based computation; -looked at electrostatic implementations of QCA, which inherently limit application spaces (e.g., due to low operating temperatures [Amlani et al 1999]); -looked at a molecular implementation [Qi et al 2003], for which there is no proven device that can be deterministically placed-and where functional correctness will be subject to small placement variations, stray charges, and so on [Niemier et al 2006]. …”