Premium
Current‐gain in FETs beyond cut‐off frequency
Author(s) -
Crupi Giovanni,
Raffo Antonio,
Vadalà Valeria,
Vannini Giorgio,
Caddemi Alina
Publication year - 2018
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.31449
Subject(s) - transistor , figure of merit , current (fluid) , electrical engineering , optoelectronics , field effect transistor , electronics , cutoff frequency , frequency response , physics , engineering , voltage
Abstract Driven by the fast‐growing demand for high‐frequency applications, electronics engineers are steadily pushing transistor technologies beyond their high‐frequency limits. A key figure of merit to quickly assess the potential of a transistor for high‐frequency applications is given by the cut‐off frequency ( f T ) that is defined as the frequency at which the short‐circuit current‐gain (h 21 ) drops to unity. However, field‐effect transistors (FETs) can exhibit a current‐gain even at frequencies beyond f T , due to the resonance of the extrinsic reactive contributions leading to a peak in the magnitude of h 21 . Based on an extensive analysis, this letter aims to demonstrate that, although not all FETs exhibit such a current‐gain peak at frequencies beyond f T , this effect is inherent in any FET devices and its appearance simply depends on the specific amount of the extrinsic reactive contributions, besides to the operating frequency.