In this case, the SAW is a voltage-controlled surface-acoustic-wave oscillator (VCSO) developed by Synergy Microwave Corp., and it can contribute to impressive phase-noise performance in synthesized sources through microwave frequencies. The tale is told in the article "VCSO Technology Silences Synthesizers" in the February issue of Microwaves & RF.
In high-frequency synthesizer lore, many different frequency sources have been used as the primary oscillator, including voltage-controlled oscillators (VCOs), yttrium-iron-garnet (YIG), and SAW oscillators, with each offering different characteristics in terms of tuning range, switching speed, and noise. The VCSO-based synthesizer in the aforementioned article tunes from 5000 to 5300 MHz with phase noise specified at -120 dBc/Hz offset 100 kHz from the carrier.