Quartz Crystals Glossary
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Vibration of a crystal is actually a mechanical vibration. However, the crystal unit can be expressed by two terminal networks if its behavior is electrically converted. The series circuit consisting of L1, C1 & R1 is related to elastic vibration, while the element C0 is connected in parallel to the series arm as a capacitance attributable to the dialectic body of a quartz crystal plate. The resistance R1 is a resonance resistance of the crystal unit at the series resonance frequency.
ESR
It is the abbreviation for "Equivalent Series Resistance." A crystal unit has a resistive element. This term is required to define and quantify that characteristic.
Etch
A process crystal manufacturers use to improve the surface condition of a crystal and to increase the frequency of a blank. The word "etch" is used to describe the material used in the etch process, as well as the process itself.
Frequency
It is a periodic repetition of an event within a unit of time. In an electrical circuit, it is the number of waves that pass through a given point in one second. In other words, it is the number of times a resonator plate oscillates or vibrates in one second. The customer usually specifies the nominal or desired frequency.
Frequency Stability
The acceptable deviation usually represented in parts per million (PPM), over a specified temperature range. Deviation is referenced to the measured frequency at +25? C.
Frequency Tolerance
The acceptable deviation from nominal frequency usually represented in parts per million (PPM), at a specific temperature, usually +25? C.
Fundamental
Lowest frequency a resonator plate will oscillate. Usually set by the physical dimensions of the plate.
Geometry
Shape of the resonator plate in a crystal unit. There are 3 geometrical forms available: Flat, Contoured, and Beveled.
Henry
Basic unit of inductance, represented by the letter "H." One henry of inductance is produced in a closed circuit by changing current uniformly at the rate of one Ampere per second.
Hertz (Hz)
Basic unit of measurement of frequency, "Hertz" used instead "cycle per second". Also used to denote one complete occurrence of an event in 1 second
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