Surface acoustic wave reference oscillators for UHF and microwave generators

The principles of operation of surface acoustic wave (SAW) delay lines and resonators are outlined and their application in stable reference UHF oscillators is described. The factors affecting oscillator stability are considered with particular emphasis on the phase noise performance. Two specific examples of these types of oscillators are presented. The first is a hybrid integrated delay-line oscillator operating at 720 MHz; a miniature version on a 16 mm square substrate is also shown. The broadband circuits permit operation at frequencies between 150 and 1200 MHz. The second is a 360 MHz resonator oscillator with an extremely good phase noise performance for use in satellite navigation systems. The main advantages compared to bulk acoustic wave (BAW) quartz-crystal oscillators, at a lower frequency, are reduced size, weight and power consumption and easier filtering of unwanted harmonics.