| Technical Topics Acceleration - acceleration sensitivity of quartz crystal resonators, resonators propensity to change frequency with acceleration. Aging - the systematic gradual change in frequency over time. Angle & Tolerance - angle of cut, Angle Rotation and tolerance in quartz crystals. Calibration & Calibration Tolerance - the adjustment the frequency of vibration to the design frequency called out by the specification. Capacitance - electrode capacitance, holder capacitance, and shunt capacitance. Crystal Blanks - the quartz wafer exclusive of any mounting structure or hermetic package. Crystal Holders - diagrams of various crystal holders. Cut - quartz crystal cuts; AT cuts, BT cuts and SC cuts. DRAT - Doubly Rotated AT Cut Crystals. Doubly Rotated AT-DRATS - Doubly Rotated AT Cut Crystals. Drive Level - the power level applied to a quartz crystal during oscillation. Frequency - the crystal's vibration mode (fundamental or overtone), the harmonics of that mode, and the physical dimensions of the quartz plate. Frequency vs Mode - vibrating quartz crystal has a number of modes being excited simultaneously Frequency vs. Package Size - chart providing the lower fundamental frequency limit for a specific holder type. Frequency Stability - The change in frequency over temperature is usually expressed in PPM/degree Celsius and is referred to as frequency stability or temperature coefficient. G Sensitivity - the frequency of the resonator is affected by gravity. Holders - hermetically sealed package types. Hysteresis - Retrace - Hysteresis or retrace is a resonator's repeatability of its frequency vs. temperature characteristic. Inflection Point - the point on the Frequency vs. Temperature curve where the change in frequency changes from positive to negative. Inversion Or Turn Points - the two inversion points, the Lower Inversion Point and the Upper Inversion Point. Metal Holders - HC Types - metal holders HC-types are through-hole devices available with either leads or pins. Military Quartz Crystals - crystals designed, manufactured and qualified to military specification MIL-PRF-3098/H Motional Capacitance & Motional Inductance - motional capacitance and motional inductance in crystal designs for oscillators. Quality Factor - Q factor, the ratio of the energy stored per cycle vs. the energy dissipated in a cycle. Perturbations - Dips - the effect of temperature dependent mode coupling. Called perturbations, band-breaks or activity dips. PIND - Particle Impact Noise Detection - the test to detect extraneous solid material. Phase Noise - random phase modulation which is present in quartz crystal oscillator. Resistance - the impedance of the crystal, measured in ohms at series resonance. Series & Parallel Resonance - series and parallel resonance of crystals. Shock - mechanical shock and thermal shock for crystals. Short Term Stability - short term stability - change of frequency typically exhibited per day. Specifying Frequency Stability - Frequency stability or temperature coefficient has two elements, frequency change (deviation) and temperature range. Spurious Modes - inharmonic modes of vibration in the quartz plate. Surface Mount Packages - there are a number of surface mount options available, some derived from metal HC-types and others in metal/plastic and ceramic packages. Vibration - crystal vibrational anomalies in a vibrating environment. |
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