Ambipolar transport in graphene offers great opportunities for novel device and circuit applications. This paper discusses the RF performance of CVD grown graphene transistors for the first time. Then, a new graphene ambipolar frequency multiplier that can operate at 1.4 GHz with extremely high output spectral purity (>; 90%) is demonstrated. These GHz graphene frequency multipliers, made from wafer-scale graphene synthesis and fabrication processes, demonstrate the great potential of graphene-based ambipolar devices for RF and mixed-signal applications.