声表滤波器热释电效应的研究

Study on Pyroelectric Effect of Surface Acoustic Wave Filter

该文分析了热释电效应产生的机理,极化强度与温度变化的关系,进而分析了钽酸锂和铌酸锂的热释电效应,这两种材料是制作声表面波滤波器的基片材料。取3只128°铌酸锂白片样品数进行试验,当温度变化时,热释电效应引起静电放电一般约为6V,但有1只器件在温度变化到-50℃左右时,会出现振荡波形峰-峰值约在25V的最大波形,这些静电会对声表面波器件本身或后级电路造成严重影响。通过分析静电放电失效模式,提出了器件防静电的方法。最后,验证了声表面波滤波器使用还原基片用于防静电的方案。

The mechanism of piezoelectric effect and the relationship between the polarization intensity and temperature are analyzed in this paper.And then the pyroelectric effects of LiTaO3 and LiNbO3 are analyzed.These two materials are the substrate materials for fabricating surface acoustic wave filters.3 samples of white 128°LiNbO3 wafesare selected to do the test.It is found that the pyroelectric effect caused by electrostatic discharge is generally about 6 volts when the temperature changes.But when the temperature changes to-55 ℃ or so,a device appears the oscillating waveform peak-to-peak value of about 25 volts waveform.This static electricity will seriously affect the surface acoustic wave device itself or the post-stage circuit.By analyzing the failure mode of the electrostatic discharge（ESD）,the anti-electrostatic method of the device is proposed in this paper.Finally,the scheme of using reduction substrate for anti-electrostatic of SAW filter is verified.