High-Frequency TaOx-Based Compact Oscillators

In this paper, we demonstrate three key features of oxide-based nano-oscillators: 1) the observation of threshold switching and filamentary oscillations in TaOx; 2) the highest frequency achieved by oxide-based oscillators; and 3) a study with linear (resistor) and nonlinear (transistor) ballasts to clearly understand the role of filament dynamics in scaling. These oscillators show frequency tunability over the range of 20 kHz-250 MHz, with 250 MHz being the highest reported frequency for this class of oscillators. Different types of ballasts show frequency tunability using two distinct methods: 1) by tuning the channel resistance of the transistor and 2) by increasing the rail voltage across the ballast-device pair. This sheds new light on the oscillator dynamics for dense oscillator arrays aimed at oscillatory neural networks and other applications.