A general theory for broad-band matching of two-ports with applications to fet amplifiers with internal feedback

We prove that the problem of broad-band matching an arbitrary linear two-port to resistive terminations by means of input and output lossless equalizers can be reduced to two passive load single-matching problems by weighting partial gains due to each equalizer with suitable frequency functions. We apply the technique to the problem of determining the maximum of an ideal rectangular gain function for an FET amplifier with internal feedback and losses. the solution is exact for zero feedback. 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.