Design and Synthesis of a VHF Surface Acoustic Wave Oscillator

Abstract

<p>This thesis covers the design and fabrication of a Surface Acoustic Wave (SAW) oscillator. The oscillator was designed to operate at 124 MHz in the fundamental mode and was constructed on an ST-X quartz substrate. The type of SAW oscillator incorporated was of the delay line type where a SAW delay line is inserted in the feedback loop of an amplifier with excess gain. The delay line exhibited a bandpass characteristic with an insertion loss of 32 dB. The oscillator has a short-term stability of 2.0 parts in 10⁷over 1 second and a medium-term stability of less than 8 ppm over 12 hours. The oscillator had an effective loaded Q of 628 and power output was -10 dBm into 50 Ω with the second harmonic down 22 dB, and the third down 33 dB. The theory of operation of the SAW delay line oscillator is covered along with fabrication procedures and experimental results.</p>