▎ 摘　　要

This letter presents a voltage-controlled tunable attenuator based on few layer graphene flakes. The proposed structure exploits the variation of graphene resistance with an applied bias voltage. The attenuator consists of a microstrip line, connected to grounded metal vias through graphene pads: when no bias voltage is applied, the resistance of graphene is high and the pads behave as open circuits, causing minimum attenuation. By increasing the bias voltage, the resistance of the graphene pads decreases, connecting the metal vias to the microstrip, thus increasing the attenuation. A prototype operating in the frequency band from dc to 5 GHz has been designed and tested. The measured attenuation ranges from 0.3 to 15 dB at 3 GHz, with a bias voltage ranging from 0 (minimum attenuation) to 6.5 V (maximum attenuation).