S parameters: a practical education

The course on radiofrequency amplifier design by the technique of S-parameters offered at Virginia Polytechnic Institute and State University is described with some emphasis on the associated laboratory portion of the course. The course begins with microstrip amplifier construction and the modeling of both lumped and distributed circuit elements. Attention is then given to the design of a transistor amplifier in the UHF spectrum. Biasing and parameter measurement are first considered. Matching networks are then designed and installed, followed by the measurement of several amplifier specifications. In five years of running the laboratory course there has never been a case of a student failing to end the course with a working amplifier. Typical amplifiers (900 MHz) have gains of 12 and 13 dB, input and output reflection coefficients below 0.05, third-order intercept points of 0-10 dBm (input), and noise figures near 5 dB.<
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