What you’ll learn:
- Basic component capabilities that will likely be required for the upcoming 6G standard.
- Why memristors are a potential 6G-related component.
- Details of one group’s work on 6G-enabled memristor switching devices.
If you’re still recovering from the 5G hype and the realities around architecture, components, and more, don’t expect too much of a break. Why? Because technical leaders across academia, industry, and standards bodies are already hard at work defining the next generation of 6G standards that will further increase speeds and move up the frequency spectrum.
Although the details of 6G aren’t immediately set in stone, researchers are already defining and exploring early versions of some of the components that may be needed.
Will memristors be a big hit?
The need for 6G leads us to memristors. Remember them? A few years ago they were touted as a new fourth passive device to join resistors, capacitors and inductors, and were supposed to be a solution to the limitations of memory components. (See references at the end of the article.).
What is a memristor? A memristor is a nonlinear two-terminal electrical component that associates the coupling of electric charge and magnetic flux, first described and named by Leon Chua in 1971. This completes the theoretical quartet of basic passive electrical components that also includes resistors, capacitors, and inductors. Memristors were supposed to be the “next big thing,” but like the tunnel diode, they didn’t take off. However, they may be successful in other specialized situations (again, like the tunnel diode) and in AI processors.
For now, the reality is that they don’t play a big role, but it may be too early to tell. Yogi Berra reportedly said, “It’s hard to predict, especially the future.” I looked at the classic “Gartner Hype Cycle” over the past few years, which divides technological progress into four stages (the innovation trigger, the peak of inflated expectations, the trough of disillusionment, and the slope of enlightenment), and I don’t see them listed in any of them.
Clearly, signal block on/off switches, handling signals at the system carrier frequency, are essential to any communications architecture. Currently, one of the fastest elements used for switching functions is silicon-on-insulator MOSFET devices, operating at tens of gigahertz. However, these are volatile and require a constant power supply to remain on, which poses a burden at the system level.
New memristor switch doubles the operating frequency of silicon devices
To address this problem, a multi-university research team has developed a memristor switch that can provide practical performance at twice the operating frequency of current silicon-based devices, covering a frequency range of up to 120 GHz, and without the need for an applied constant voltage.
The new switches use a non-volatile material called hBN (hexagonal boron nitride) that allows the on or off state to be activated by applying a voltage pulse instead of a constant control voltage (a solid-state analogue of a latching electromechanical relay), resulting in significant energy savings.
Previously, extremely fast switches have been experimentally developed by combining two-dimensional networks with hBN to form a surface. With this arrangement, the device could reach frequencies up to 480 GHz, but it could only be used for up to 30 cycles, making it unlikely to be of practical use.
The new device uses the same materials but arranged in layers (12 to 18 layers total) that operate at 260GHz and have high enough stability to be implemented in electronic devices. (Figure 1).
