Flexible and Transparent All-Graphene Circuits for Quaternary Digital Modulations

TL;DR

This paper presents a fully flexible, transparent all-graphene circuit capable of quaternary digital modulation, reducing complexity and enabling high-speed, flexible communication systems on transparent substrates.

Contribution

It demonstrates the first all-graphene modulator circuit for quaternary digital signals, utilizing graphene's ambipolarity and nonlinearity for simplified, flexible, and transparent communication components.

Findings

Achieved 4-ASK and QPSK modulation with 1 and 2 graphene transistors.

Circuit exhibits ~95% transparency and high flexibility.

Presents a significant step toward integrated flexible communication systems.

Abstract

In modern communication system, modulation is a key function that embeds the baseband signal (information) into a carrier wave so that it can be successfully broadcasted through a medium such as air or cables. A flexible signal modulation scheme is hence essential to wide range of applications based on flexible electronics. Here we report a fully bendable all-graphene modulator circuit with the capability to encode a carrier signal with quaternary digital information for the first time. By exploiting the ambipolarity and the nonlinearity in a graphene transistor, we demonstrated two types of quaternary modulation schemes: 4-ary amplitude-shift keying (4-ASK) and quadrature phase-shift keying (QPSK). Remarkably, 4-ASK and QPSK can be realized with just 1 and 2 all-graphene transistors, respectively, representing a drastic reduction in circuit complexity when compared with conventional digital modulators. In addition, the circuit is not only flexible but also highly transparent (~95% transmittance) owing to their all-graphene design with every component (channel, interconnects, load resistor, and source/drain/gate electrodes) fabricated from graphene films. Taken together, these results represent a significant step toward achieving a high speed communication system that can be monolithically integrated on a flexible and transparent platform.