a tuned oscillator utilizing a thin film ferromagnetic resonator is disclosed . the oscillator comprises an active element for oscillator and a yig thin film resonator connected to the active element as a part of feed - back circuit for the active element . the yig thin film resonator is applied with a bias magnetic field perpendicular to a surfce of a yig disk which is generated by a permanent magnet for a fixed component and a coil for a variable component for the resonance frequency . the resonance frequency is stabilized by use of a pll circuit connected to an output of the oscillator and feeding back to the coil . since the yig thin film tuned oscillator has a high q value , high quality communication signal processing can be achieved . the yig tuned oscillator is used as local oscillator for a transciever .