A systematic design procedure for a GaAs FET discriminator (sloped) amplifier that is used for direct microwave frequency discrimination has been developed. Active type discriminators have several advantages over the passive interferometer type which has a limited accuracy. Their discrimination function is based on the utilization of a GaAs FET amplifier with a linearly decreasing Gain/Frequency characteristic. The practical realization of a discriminator amplifier requires accurate determination of the parameters that characterize the FET, and an efficient design method. The graphical and CAD design technique that is used in this thesis results in stable amplifiers having characteristics close to the desired. The program COMPACT is used for analysis and optimization of the circuit.
The effectiveness of the design procedure is tested by fabricating four discriminator amplifiers designed in the 3.7-4.2GHz band. The experimental performance is in good agreement with the theoretical predictions.