Resistive Graphene FET Subharmonic Mixers: Noise and Linearity Assessment

We report on the first complete RF characterization of graphene field-effect transistor subharmonic resistive mixers in the frequency interval f_RF=2-5 GHz . The analysis includes conversion loss (CL), noise figure (NF), and intermodulation distortion. Due to an 8-nm thin Al₂O₃ gate dielectric, the devices operate at only ~ 0 dBm of local oscillator (LO) power with an optimum measured CL in the range of 20-22 dB. The NF closely mimics the CL, thus determining the noise to be essentially thermal in origin, which is promising for cryogenic applications. The highest input third-order intercept point is measured to be 4.9 dBm at an LO power of 2 dBm.