Synthesis of modulation insensitive N-path filters

Through the intermediary of state-variable equations, realization of an N-path filter from a prescribed transfer function is obtained. An equivalence is found which shows how passive RC circuits incorporating time-variable gyrators can be used to realize N-path filters. It is also proved possible to realize any stable transfer function as an N-path filter structure and that the system is insensitive to the frequency of the multiplying signals or the frequency of the gyration conductance. „Listen again to this. I have seen moonlight Sometimes the statues leaning over like reeds In the middle of living fruit, – the statues”[1,p. 95].