In this letter, we demonstrate that a graphene monolayer, over which three metallic electrodes forming a coplanar waveguide are patterned, acts as a frequency multiplier and generates frequencies at least up to 40 GHz. These results show that monolayer graphene is a natural frequency multiplier.

We present the modeling and measurements of microwave propagation in a coplanar waveguide over graphene in the range of frequencies 40 MHz-110 GHz, which suggest that graphene could work well in a very large bandwidth. Graphene is acting as a natural matching device because its equivalent resistance at these frequencies is able to vary more than 75% when DC biases are applied in the range −4 V to 4 V on the graphene waveguide.

We present a review of the applications of the Wigner distribution function in various areas of signal processing: amplitude and phase retrieval, signal recognition, characterization of arbitrary signals, optical systems and devices, and coupling coefficient estimation in phase space. Although reference is made to specific signals and systems, the mathematical formulation is general and can be applied to either spatial, temporal, or spatio-temporal phase spaces, to coherent, partially coherent, or discrete signals. The universal and intuitive character of the Wigner distribution approach to signal characterization and processing and its simplicity in solving many issues are evidenced throughout the paper.

We present a graphene-based ballistic diode, which is able to rectify an incident signal due to an oblique gate positioned between the two terminals of the device. The operating point of the diode can be controlled by the applied gate voltage, whereas the current-voltage dependence of the device can be changed by varying the inclination angle of the gate. In particular, the ideality factor of the graphene-based diode can take values higher or lower than 1 by modifying this inclination angle. The rectifying properties of the graphene diode are thus tunable, in deep contrast with semiconductor-based diodes.