Asymmetric polyphase filter

Abstract

Abstract Asymmetric polyphase filer having first to fourth input terminals for applying thereto a 4-phase input signal including first to fourth signal vectors, respectively, which succeed one another in phase each time through 90°, first to fourth intercoupled identical filter sections, respectively, connected to the terminals, at least one of the odd and even filter sections being coupled to two output terminals, said filter sections having constant reactances. To provide the possibility of an integrable realization of an asymmetrical filter transfer characteristic which is highly insensitive to component variations, the first and third filter sections and the second and fourth filter sections constitute a balanced in-phase and a balanced quadrature filter section circuit, respectively, in which the mutually corresponding reactances of the first and third filter sections and those of the second and fourth filter sections are constituted by active balanced integrators each having a balanced input terminal pair and output terminal pair with a balanced amplifier stage arranged therebetween, the output terminal pair being fed back to the input terminal pair via two mutually equal capacitances couplings being provided between the ouptut terminal pair of each of the integrators of the in-phase filter section circuit via two mutually equal resistors to the input terminal pair of the corresponding integrator of the quadrature filter section circuit, and conversely, which couplings are pairwise anti-reciprocal with respect to one another.

Inventors

• 👤 Johannes O. Voorman

Bibliographic Details