Publication Date


Document Type


First Advisor

Newell, D. E.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Industry and Technology


Oscillators; Crystal--Noise


This study presents a logical technique for the analysis and design of low noise crystal oscillator circuits, Basic noise mechanisms are reviewed, such as thermal noise and l/F noise. The quartz crystal is represented as a noise equivalent circuit and the crystal's noise contributions are derived. The active circuit is then discussed using the hybrid rr model. Considera­tions are given for the shot noise currents and the effects of the base spreading resistance on the best achievable noise performance. Since noise is a random phenomena, statistical calcula­tions such as the Allan Variance, Standard Deviation and the Autocorrelation Function are derived. The spectral density is represented in the frequency domain and a conversion technique for frequency domain data to time domain is developed. The con­version allows a fast method of representing the short-term stability of an oscillator. Measurement techniques for the collection of noise data are discussed using the frequency counter and the spectrum analyzer. Finally, a computer program called "NOISEY" was designed as an aide in evaluating crystal oscillator circuits. "NOISEY" looks at the crystal's equivalent noise circuit in junction with the active device of the oscillator. An evaluation can be made of the performance of an oscillator for noise content using this program.


Includes bibliographical references (leaf 95)


109 pages




Northern Illinois University

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