Spectrospin Ag

Roland Kappeli

Anton Kuster

Method for reducing the content of spurious signals in the output signal of a mixer and mixer designed for carrying out the method according to the invention. When using quadrature mixtures as generators for tunable rf signals it has been found to be a disadvantage that differences in the two channels of the quadrature mixers lead to a high content of undesirable mixture signals. The content of disturbing mixture signals in the output signals of such mixers is reduced according to the invention by feeding the ring modulators of the quadrature mixer with signals differing from pure sine oscillations, which are phase-shifted relative to each other by 90.degree. and which have been determined in such a manner that all pairs of d.c. signals supplied to the two ring modulators result in output signals which have all the same amplitude and each of which has a phase position conforming exactly to the phase position to which the respective pair of d.c. signals is assigned. By supplying these signals in a cyclical sequence one obtains a modulation signal of predetermined frequency supplying an output signal which is substantially free from undesirable mixture signals and whose frequency is displaced relative to the frequency of the supplied carrier signals by the frequency of the modulation signal.

Growing community of inventors

Oberhittnau, Switzerland

Roland Kappeli