Low noise 9-GHz sapphire resonator-oscillator with thermoelectric temperature stabilization at 300 Kelvin

The authors report on an X-band microwave oscillator incorporating a room temperature thermoelectric stabilized sapphire resonator operating at 9.00000 GHz. With a Galani type stabilization scheme they have measured a reduced single sideband phase noise of about -124 dBc/Hz at 1 kHz with a f/sup -3/ dependence. The measurement was limited by the flicker noise of the phase detector in the feedback electronics. The frequency stability was also measured; at an integration time of 0.1 seconds a /spl delta/f/f of about 10/sup -11/ with a /spl tau//sup 0.7/ dependence was measured. The frequency drift strongly correlated with ambient temperature fluctuations.>