Extremely Low Phase Noise SAW Resonator Oscillator Design and Performance

SAW resonator designs with overnioded cavities. very wide apertures. dual apertures, etc.. as well as modified fabrication techniques. have been used to realize an overall reduction in an oscillator's phase noise spectrum. i.e.. white +M. flicker FM. and random walk FM. The incident RF power handling capability of these SAW resonator designs is in excess of +20 dBm. a key requirement to achieving an extremely low oscillator phase noise floor. A new processing technique was also employed to reduce both the flicker FM and random walk FM phase noise levels. Using these various techniques a 5 to 15 dB improvement in the overall phase noise spectrum for several prototype oscillators was demonstrated. Specifically. a white OM noise floor of -182 dBclHz. and a flicker FM noise level of -1 10 dBc/Hz at fm = 100 Hz carrier offset were measured on several 500 MHz SAW resonator oscillators. A 42s MHz SAW resonator oscillator exhibited a fractional frequency stability. w (T). of 1~10-~' for T = lx104 seconds. This exceptionally go2d time domain stahility corresponds to a random walk FM noise process for which S,,(fm) = 6 Hz2lHz at fm = l~lO-~ Hz. This data

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