VO$_2$ oscillator circuits optimized for ultrafast, 100 MHz-range operation

TL;DR

This paper demonstrates how to significantly increase the oscillation frequency of VO$_2$ memristor circuits into the 100 MHz range through optimized design, enabling ultra-fast, energy-efficient neural network applications.

Contribution

It introduces optimized circuit and sample layouts that boost VO$_2$ oscillator frequencies by over tenfold, and studies the physical limits of their switching dynamics.

Findings

Oscillation frequency increased to over 100 MHz.

Optimized layout significantly improves performance.

Physical limits of switching times are characterized.

Abstract

Oscillating neural networks are promising candidates for a new computational paradigm, where complex optimization problems are solved by physics itself through the synchronization of coupled oscillating circuits. Nanoscale VO$_2$ Mott memristors are particularly promising building blocks for such oscillating neural networks. Until now, however, not only the maximum frequency of VO$_2$ oscillating neural networks, but also the maximum frequency of individual VO$_2$ oscillators has been severely limited, which has restricted their efficient and energy-saving use. In this paper, we show how the oscillating frequency can be increased by more than an order of magnitude into the 100 MHz range by optimizing the sample layout and circuit layout. In addition, the physical limiting factors of the oscillation frequencies are studied by investigating the switching dynamics. To this end, we investigate how much the set and reset times slow down under oscillator conditions compared to the fastest switching achieved with single dedicated pulses. These results pave the way towards the realization of ultra-fast and energy-efficient VO$_2$-based oscillating neural networks.