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晶体振荡器的常见故障是开路(为接触不良、晶体损坏等)和频偏。有些维修人员用测晶振电容值来判断其好坏,虽然该法可判别晶振的开路故障,但对频偏故障却无能为力,容易造成误判。其理由如下: 从结构上看,静态下的晶振相当一个平板电容器,设其等效电容为C_0,它的大小与晶片的材质、几何尺寸及电极面积有关,对某一晶振成品而言,可认为C_0为定值。当晶振工作时,动态参数将发生变化,其振动惯性可等效为一个电感L,晶片的弹性可等效为一个电容C,且C还小于C_0,晶片振动摩擦损耗了等效电阻R,上述三个参数串联后与C_0并联,其等效电路为图1
Crystal oscillator common fault is open (poor contact, crystal damage, etc.) and frequency offset. Some maintenance personnel to measure the value of the crystal oscillator to determine its good or bad, although the law can determine the crystal oscillator open fault, but the frequency offset failure can not help, likely to cause miscarriage of justice. The reasons are as follows: From a structural point of view, the static crystal oscillator quite a flat capacitor, set its equivalent capacitance C_0, its size and the wafer material, geometry and electrode area, for a finished crystal, Think C_0 is constant. When the crystal work, the dynamic parameters will change, the vibration inertia can be equivalent to an inductance L, the elasticity of the wafer can be equivalent to a capacitor C, and C is less than C_0, the chip vibration friction loss equivalent resistance R, the above Three parameters in series with C_0 parallel, the equivalent circuit shown in Figure 1