Abstract

A new, analytic large-signal model for N-channel SiGe Modulation Doped Field Ef-fect Transistors (MODFETs) is presented. The model is based on a non-linear equivalent circuit and can be employed to fit the characteristics in the sub-threshold, linear and saturation operating region from DC to high frequencies. In addition to the non-linear I ds current source, gate/drain-and gate/source capacitance elements, it contains a dispersion model to account for the observed low-frequency dispersion effects in the devices. This contribution focuses on the reliable pre-diction of large-signal characteristics such as gain compression and third order intercept points by ex-tending the covered gate-source and drain-source voltage regimes of the model. Device characterisa-tion has been carried out up to 50GHz and allows for the extension of the model’s valid frequency range well beyond the device’s measured transit frequency of around 40GHz.