Ultimate theoretic performance of microwave FET amplifiers with internal feedback

It is proved, by introducing weighting functions, that the problem of broadband matching an arbitrary linear two-port with input and output lossless equalizers (resistive terminations) is equivalent to two passive load single-matching problems. The technique is applied to the problem of determining the maximum of an ideal rectangular gain function for an FET feedback amplifier. For finite feedback the ideal input equalized gain is exact, whereas the output least upper bound is approximate. The results, in effect, provide a figure of merit for a given FET which is a useful yardstick against which practical designs can be evaluated. Some numerical results are presented