Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109, USA.
Nat Commun. 2012;3:1018. doi: 10.1038/ncomms2021.
In modern communication systems, 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. Here we report a flexible all-graphene modulator circuit with the capability of encoding a carrier signal with quaternary digital information. By exploiting the ambipolarity and the nonlinearity in a graphene transistor, we demonstrate two types of quaternary modulation schemes: quaternary amplitude-shift keying and quadrature phase-shift keying. Remarkably, both modulation schemes can be realized with just 1 and 2 all-graphene transistors, respectively, representing a drastic reduction in circuit complexity when compared with conventional modulators. In addition, the circuit is not only flexible but also highly transparent (~95% transmittance) owing to its all-graphene design with every component (channel, interconnects, load resistor and source/drain/gate electrodes) fabricated from graphene films.
在现代通信系统中，调制是将基带信号（信息）嵌入载波的关键功能，以便能够通过空气或电缆等介质成功广播。在这里，我们报告了一种具有灵活的全石墨烯调制器电路，该电路能够对载波信号进行四进制数字信息编码。通过利用石墨烯晶体管的双极性和非线性，我们演示了两种类型的四进制调制方案：四进制振幅键控和正交相移键控。值得注意的是，这两种调制方案都可以分别仅使用 1 个和 2 个全石墨烯晶体管来实现，与传统调制器相比，这大大降低了电路的复杂性。此外，由于其所有组件（通道、互连、负载电阻和源/漏/栅电极）均由石墨烯薄膜制成，因此该电路不仅具有灵活性，而且还具有很高的透明度（~95%的透光率）。
