Nano Lett. 12, 2067–2070 (2012)

Graphene is a promising material whose high mobility makes it of interest for high-frequency electronic applications, although the lack of a bandgap and the ambipolar device characteristics are still challenges to be overcome. Turning such properties into virtue, Hong-Yan Chen and Joerg Appenzeller have now demonstrated a graphene-based electronic frequency tripler. The device is based on two graphene transistors coupled together. If biased appropriately, such a tripler converts an oscillating voltage applied to both transistors simultaneously into a frequency-tripled signal across both transistors. In most cases the signal of a frequency tripler still contains a large contribution at the fundamental frequency, which means the spectral purity lies below 15%. For the graphene triplers demonstrated here, however, the spectral purity at a frequency of 600 Hz is 70%, making this a promising demonstration of using graphene's unique properties for novel electronics devices.