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 TaO x ; 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.