# Analog and digital phase modulation of spin torque nano-oscillators

## TL;DR

This paper demonstrates advanced phase modulation techniques for spin torque nano-oscillators, enabling reliable wireless data transmission and voice communication despite inherent phase noise challenges.

## Contribution

It introduces a novel PSK technique combining modulation and injection locking in STNOs, validated with experimental results for data and voice transmission.

## Key findings

- Achieved phase shifts up to 2.1 radians.
- Data transmission rates up to 4 Mbit/s.
- Voice transmission over 10 meters.

## Abstract

Spin torque nano-oscillators (STNO) are nanoscale devices with wide band frequency tunability. Their multifunctional RF properties are well suited to define novel schemes for wireless communications that use basic protocols for data transmission such as amplitude, frequency and phase shift keying (ASK, FSK, PSK). In contrast to ASK and FSK, implementation of PSK is more challenging for STNOs because of their relatively high phase noise. Here we introduce a special PSK technique by combining their modulation and injection locking functionality. The concept is validated using magnetic tunnel junction based vortex STNOs for injection locking at 2f and f/2 showing phase shifts up to 2.1rad and data transmission rates up to 4Mbit/s. Quadrature phase shift keying and analog phase modulation are also implemented, where the latter is employed for voice transmission over a distance of 10 meters. This demonstrates that STNO phase noise and output power meet the requested performances for operation in existing communication schemes.