Rectifier modulators with frequency-selective terminations, with particular reference to the effect of even-order modulation products

Solutions are obtained for the modulation-product currents in series- and shunt-type rectifier modulators by separating out an equation for each possible modulation-product frequency and by assuming (a) square-wave switching of non-reactive rectifiers, and (b) signal-path terminating impedances which are a pure but not necessarily constant resistance¿or zero or infinite¿at each modulation-product frequency involved. The conditions under which there are no even-order modulation-product currents are determined, and the influence of such currents when they do exist is examined. Experimental results confirm the theory. It is shown that all the working and conclusions apply exactly to the ring modulator, provided that terminations required for odd-order modulation-product frequencies are applied in the output loop and those required for even-order frequencies are applied in the input.