Transport conductivity of graphene at RF and microwave frequencies

We measure graphene coplanar waveguides from direct current (DC) to a frequency integral = 13.5 GHz and show that the apparent resistance (in the presence of parasitic impedances) has an omega(2) dependence (where omega = 2 pi f), but the intrinsic conductivity (without the influence of parasitic impedances) is frequency-independent. Consequently, in our devices the real part of the complex alternating current. (AC) conductivity is the same as the DC value and the imaginary part is similar to 0. The graphene channel is modeled as a parallel resistive-capacitive network with a frequency dependence identical to that of the Drude conductivity with momentum relaxation time similar to 2.1 ps, highlighting the influence of AC electron transport on the electromagnetic properties of graphene. This can lead to optimized design of high-speed analog field-effect transistors, mixers, frequency doublers, low-noise amplifiers and radiation detectors.