基于AD698的粗糙度测试仪信号调理电路的设计

Design of the signal modulation circuit of roughness tester based on AD698

LVDT(Linear Variable Differential Transformer,可变差分变送器)是触针式粗糙度测试仪的感测部件。当粗糙度测试仪的触针沿着物件表面滑动时,LVDT将触针的纵向机械位移转变成与之成比例的直流信号,从而感测该位移的大小和方向。以往对LVDT输出信号的处理多采用分立元件电路或AD598集成芯片,采用AD698集成芯片能有效减少由温度导致的激励信号飘移,同时,本文将引入一种高灵敏度设计方案,能在不增加输出噪声的情况下,有效提高灵敏度,从而在整体上提高该调理模块的性能。

The AD698 （Linear Variable Differential Transformer）is the core component of contact（Stylus）instruments of surface tester. The LVDT transformed the longitudinal mechanical displacement into measurable DC output when the stylus of the surface tester slides on the surface of the object to be gauged. In the old design of the signal conditioning subsystem,we commonly used the discrete component circuits or AD598. The employment of the AD698, we could efficiently reduce the voltage drifts of the excitation signal resulting from the change of the temperature, we also make it possible to obtain high sensitivity, but not to enhance the output noise.