This paper presents a small-signal characterization work on a recently developed 55 nm SiGe BiCMOS technology from STMicroelectronics. The SiGe HBT from a prototype BiCMOS 55 nm process was investigated up to 325 GHz. The full S-parameters from DC to 325 GHz under multiple bias conditions are presented for the first time for a SiGe HBT. A usual and simple approach for the off-wafer calibration associated to an on-wafer de-embedding procedure was used and remained valid up to 325 GHz thanks to a size reduction of the test structures. The extracted 300/325 GHz f(T)f(MAX) couple, reached at 14 mA/mu m(2) collector density and 1.2 V collector-emitter voltage, was validated up to 325 GHz. (C) 2016 Elsevier Ltd. All rights reserved.