Publication Date

1982

Document Type

Dissertation/Thesis

First Advisor

Newell, Darrell E.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Industry and Technology

LCSH

Oscillators; Crystal; Electronic circuits--Temperature compensation

Abstract

This thesis proposes a method of temperature compensating a special SC Cut quartz crystal oscillator. Two modes, the B mode and the C mode, of the SC Cut are resonated simultaneously; one is used as a temperature sensor and the other is compensated for a high stability frequency output. The frequency of the C mode varies cubically over temperature about 60 parts per million within -40°C to + 100°C. The frequency of the B mode varies linearly at about -25 ppm per degree Celsius. The B mode frequency is used as an "on-blank" temperature sensor to generate a modulating voltage to compensate the C mode. A dual mode oscillator is developed which allows the frequency of the C mode to be controlled without affecting the B mode. A method of digital compensation is presented. A frequency counter uses a time base, derived from the C mode, to count the difference frequency after mixing the B and C modes. Its output will be a digital representation of the temperature of the crystal. It will be used to directly address a memory containing the compensation information. The memory systems used are RAMs to demonstrate the on-site programming and compensation of the oscillator in one step as a labor saving measure in manufacturing. The digital outputs containing the programmed compensation information are converted to an analog voltage using a digital-to-analog converter and a sample-and-hold circuit. The analog voltage output is tied back to the varactor in the C mode oscillator. The compensation information is programmed automatically using a phase-locked-loop, an up/down counter and a track-and-hold circuit all of which are connected to the oscillator via a 24 pin ribbon cable only during the programming phase. The system was compensated from -20° to + 70° Celcius.

Comments

Includes bibliographical references.||Includes illustrations.

Extent

viii, 128 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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