The optimum performance of mixers is investigated in this book by a thorough analysis of a simple model, the class of purely resistive mixers having ideal selective filters. The effect of parasitic reactances is neglected. This theoretical work also has practical applications even with these idealizations, one reason being that today's semiconductor technology is capable of producing mixer diodes, such as Schottky-barrier diodes, that exhibit almost purely resistive characteristics even at microwave frequencies.
After a general introduction to the problems the author proposes for solution, he presents the methods of analysis of different mixers employing linear, periodically time-varying resistances. A logical classification system based on the terminations offered to the undesired out-of-band frequencies for the different matrices, such as Z-, Y-, H-, and G-matrices, which had to be used for the analysis.
Next, fundamental limits on the performance of resistive waveform is obtained by pumping a nonlinear device in the imbedding network. The waveform thus depends on the device used, the method of pumping employed, and the imbedding network itself. The last chapter deals with these realistic conditions by analyzing and comparing mixer circuits that employ diodes with exponential characteristics.
All of these analytic approaches are brought to bear in a systematic and complete way on the various types of network matrices that form the basis for the classification of the mixers. In each case, the conditions necessary to achieve optimal operation are given. Some of these conditions are well known, but the author has extended them in some cases and derives new conditions as well.