Design of Wide Band Amplifiers Using Hybrid Integrated Techniques

This article deals with the design of wide band transistor amplifiers. The effects of parasitic elements are significant in the high frequency circuits mounted traditionally and they can only be partially computed. That is why, at present, good quality wide band transistor amplifiers can only be realized using hybrid techniques in an economical production environment. Precise equivalent circuits of high frequency transistors cannot be given, so these devices are characterized by the scattering parameters. Using a digital computer in order to analyse transistor amplifiers the impedance, admittance, transmission and scattering parameters must be converted rationally. To compensate the circuits at high frequencies inductive elements are needed. Using thin film hybrid techniques, the inductor can be realized on a ceramic substrate as an open, i.e. asymmetrical, microstrip transmission line section. Up to now, in our institute, two circuit families of wide band amplifiers based on the above thin film hybrid principles have been produced. These circuits are designed for use as general purpose amplifiers but they are also suitable for CATV and measuring systems.