In this work, we present the first small signal characterization of a reconfigurable field effect transistor. The device under test is a back-bias RFET integrated into an industrial 22nm FDSOI platform. These devices are particularly interesting for CMOS co-design as they enable a frequency doubling functionality using a single transistor, without the need for inductive elements. Extraction of figures of merit and a comprehensive small signal analysis are performed. It is demonstrated that an ambipolar back-bias reconfigurable field-effect transistor can be modelled using a conventional small-signal equivalent circuit. This shows promise for modelling engineers and circuit designers to explore innovative applications of this new emerging technology.