Spectral performance of sapphire dielectric resonator-controlled oscillators operating in the 80 K to 275 K temperature range

This paper reports on the phase noise performance obtained for X-band oscillators using cooled, sapphire dielectric resonators as the frequency-determining element. We report on results obtained using: (1) a TE-cooled, high-order mode resonator purchased from Poseidon Industries exhibiting a loaded Q of 140,000 at an operating temperature of 275 K, and (2) a low-order (TE02) mode resonator fabricated at Westinghouse exhibiting a loaded Q of 350000 at an operating temperature of 77 K. The oscillator sustaining stage designs incorporate GaAs amplifier flicker-of-phase noise feedback reduction techniques as well as a technique that avoids the need for X-band signal amplification altogether. Sustaining stage open loop, flicker of phase noise levels obtained are typically 20 dB below those normally exhibited by GaAs X-band amplifiers.