Explanation of Crystal Units
By Macrobizes
June 10, 2004
Page: Previous 1 2 3 4 Next 1 Equivalent Circuit
Vibration of a crystal unit is actually mechanical vibration. However, the crystal unit can be expressed by a two terminal network if its behavior is electrically converted. The series circuit consisting of L1, C1, and R1 is related to elastic vibration, while the element C0 connected in parallel to the series arm as a capacitance attributable to the dielectric body of a quartz crystal plate. The resistance R1 is a resonance resistance of the crystal unit at the series resonance frequency. (See Fig.1.)
2 Frequency-Temperature
Characteristics of an AT-cut The frequency-temperature characteristics of an AT-cut crystal unit most generally used at present are expressed by cubic curves. (See Fig.2.) A crystal plate is cut at an angle at which a required frequency tolerance is obtained in the given operating temperature range. Actually, however there can be some dispersion in apparent cutting angle due to the result of cutting and polishing accuracy in the successive processes. Therefore, it is necessary to raise processing accuracy.
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