Nonreciprocal circuit device with a dielectric film between the magnet and substrate

Abstract

A nonreciprocal circuit device having a circuit element on a dielectric substrate providing at least part of a low-pass filter, the nonreciprocal circuit device having less interference and irregular operation caused by spurious radiation, and in addition, with reduced insertion loss. A lumped constant isolator (an example of a nonreciprocal circuit device) includes a magnet provided for applying a DC magnetic field to a magnetic assembly, which in turn has multiple intersecting central electrodes provided adjacent to a ferrite body. A dielectric substrate is disposed in between the permanent magnet and the magnetic assembly. An inductor forming part of a &pgr;-type low-pass filter is provided as an example of a circuit element on the dielectric substrate, a dielectric layer or film being disposed between the dielectric substrate and the magnet.