Due to its remarkable properties, graphene-based devices are particularly promising for optoelectronic applications. Thanks to its compatibility with standard silicon technology, graphene could compete III-V compounds for the development of low cost and high-frequency optoelectronic devices. We present a new optoelectronic device that consists in a coplanar waveguide integrating a commercially-available CVD graphene active channel. With this structure, we demonstrate high-frequency (30 GHz) broadband optoelectronic mixing in graphene, by measuring the response of the device to an optical intensity-modulated excitation and an electrical excitation at the same time. These features are particularly promising for RADAR and LIDAR applications, as well as for low-cost high-speed communication systems.