Microwave amplifiers combine active elements with passive transmission line circuits to
provide functions critical to microwave systems and instruments. The history of
microwave amplifiers begins with electron devices using resonant or slow-wave
structures to match wave velocity to electron beam velocity.
The design techniques used for BJT and FET amplifiers employ the full range of concepts
we have developed in the study of microwave transmission lines, two-port networks and
Smith chart presentation.
The development of S-parameter matrix concepts grew from the need to characterize
active devices and amplifiers in a form that recognized the need for matched termination
rather than short- or open-circuit termination. Much of the initial work was performed at
the Hewlett-Packard Company in connection with