L-NESS, Department of Physics, Politecnico di Milano, Polo di Como, Via Anzani 42, 22100 Como, Italy.
ACS Nano. 2013 Jun 25;7(6):5588-94. doi: 10.1021/nn401933v. Epub 2013 Jun 3.
Ring oscillators (ROs) are the most important class of circuits used to evaluate the performance limits of any digital technology. However, ROs based on low-dimensional nanomaterials (e.g., 1-D nanotubes, nanowires, 2-D MoS2) have so far exhibited limited performance due to low current drive or large parasitics. Here we demonstrate integrated ROs fabricated from wafer-scale graphene grown by chemical vapor deposition. The highest oscillation frequency was 1.28 GHz, while the largest output voltage swing was 0.57 V. Both values remain limited by parasitic capacitances in the circuit rather than intrinsic properties of the graphene transistor components, suggesting further improvements are possible. The fabricated ROs are the fastest realized in any low-dimensional nanomaterial to date and also the least sensitive to fluctuations in the supply voltage. They represent the first integrated graphene oscillators of any kind and can also be used in a wide range of applications in analog electronics. As a demonstration, we also realized the first stand-alone graphene mixers that do not require external oscillators for frequency conversion. The first gigahertz multitransistor graphene integrated circuits demonstrated here pave the way for application of graphene in high-speed digital and analog circuits in which high operating speed could be traded off against power consumption.
环形振荡器 (ROs) 是用于评估任何数字技术性能极限的最重要的电路类别。然而，基于低维纳米材料（例如，1-D 纳米管、纳米线、2-D MoS2）的 RO 由于电流驱动能力低或寄生较大，迄今为止其性能受到限制。在这里，我们展示了由化学气相沉积生长的晶圆级石墨烯制成的集成 RO。最高振荡频率为 1.28GHz，最大输出电压摆幅为 0.57V。这两个值仍然受到电路中的寄生电容限制，而不是石墨烯晶体管元件的固有特性，这表明可以进一步改进。所制造的 RO 是迄今为止在任何低维纳米材料中实现的最快的，并且对电源电压波动的敏感性也最低。它们代表了任何类型的第一个集成石墨烯振荡器，也可以在模拟电子的广泛应用中使用。作为演示，我们还实现了第一个不需要外部振荡器进行频率转换的独立石墨烯混频器。这里展示的第一个千兆赫多晶体管石墨烯集成电路为石墨烯在高速数字和模拟电路中的应用铺平了道路，在这些应用中，工作速度可以与功耗相权衡。
