The crystal unitis an electronic device that is capable of composing a frequency generatorcircuit with an extremely high stability .It has achieved high degree ofcompactness and high performance .
Vibration of a crystal unitis actually mechanical vibration. However, the crystal unit can be expressed bya two-terminal network if its behavior is electrically converted. The seriescircuit consisting of L1, C1,and R1 is related to elastic vibration ,while theelement C0 connected in parallel to the series arm as A capacitanceattributable to The dielectric body of a quartz crystal plate .The resistanceR1 is a resonance resistance of The crystal unit at the series Resonancefrequency. (See Fig.1.)
