Modelling of transistor feeding structures based on electro-magnetic field simulations

The reliable and efficient design of monolithic millimetre-wave integrated circuits (MMICs) mandates accurate transistor models. With increasing frequency the dimensions of the transistor feeding network can not be neglected and an impedance transformation within the feeding network occurs. MMIC designers demand for versatile and scalable transistor models. This makes a precise knowledge of the transistor feeding structures and their separation from the intrinsic transistor necessary. Electro-magnetic (EM) field simulations are carried out and based on these, the scalable transistor feeding structure is extracted as a lumped circuit network. In this paper we demonstrate the modelling and parameter extraction of a metamorphic high electron mobility transistor (mHEMT) in common-gate (CG) configuration up to 325 GHz. A step-by-step description of the procedure is given, followed by a measurement-based verification of the approach up to 110 GHz.