The modelling of passive circuit elements and FETs for analogue circuits

The reliable design of gallium arsenide monolithic microwave integrated circuits (MMICs) requires accurate computer aided design software packages. At the present time most computer aided design (CAD) packages are based on equivalent circuit models derived from measured data. This approach relies on extensive experimental characterisation of devices and circuits after fabrication. Furthermore, the majority of CAD routines are limited to linear circuit models (or at best linearised models). Comprehensive physical device models have been developed for GaAs devices over the past six years and have been incorporated into simple MMIC design software. An important advantage of this approach is that since the model relies only on the material and fabrication process data it is possible to predict the device characteristics before fabrication. Unlike equivalent circuit models, there is no requirement for DC and RF measurements to derive the model, and a more flexible and general approach is assured