Newell, Darrell E.
M.S. (Master of Science)
Department of Industry and Technology
Oscillators; Crystal; Electronic circuits--Temperature compensation
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.
Miguel, Edward K., "A temperature compensated SC cut quartz crystal oscillator" (1982). Graduate Research Theses & Dissertations. 905.
viii, 128 pages
Northern Illinois University
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