Simpler, more accurate models and design for amplifiers and oscillators

The essential preliminaries to realistic designs and simulation of linear and nonlinear circuits are accurate measurements and modelling of all the components, strays and parasitics which together govern the performance of a given circuit realisation at all frequencies of interest. After a brief summary covering important aspects of measurements using state-of-the-art equipment and techniques, illustrated by S-parameters measured on ten devices, the author discussed basic questions concerning modelling before moving on to give examples using the chosen models in engineering applications. A flow chart showing the relationships between S-parameters, admittances and network functions such as transducer power gain, reflection and a transfer function which enables stability to be assessed is given. In particular, the influence of internal feedback (always present in transistors) on reflection and transmission properties is considered