Low phase-noise tunable oscillators using magnetostatic wave resonators

Two low phase-noise tunable oscillators were realised using magnetostatic wave (MSW) resonators. Operating ranges are 6.25-12.5 GHz and 9.875-11 GHz. Spurious oscillation at half the output frequency (f/2 bifurcation) is a typical source of phase-noise degradation but can be prevented by insertion of dissipative elements to selectively absorb f/2. Degradation of phase-noise caused by the strong non-linear (chaotic) behaviour of MSW resonators can be eliminated by controlling the signal level in the oscillator. Optimisation of resonator dimensions, housing geometry and magnetic bias field distribution avoids tuning hysteresis caused by parasitic modes of the resonator. Excellent phase-noise results are obtained in this way.