声表面波器件的反射特性及性能  

Reflection Property and Performance of Surface Acoustic Wave Devices

作　　者：王添仙 谢立强 邢建春 朱玺峰 WANG Tianxian , XIE Liqiang , XING Jianchun , ZHU Xifeng(College of Defense Engineering ,Army Engineering University, Nanjing 210007, China)

机构地区：[1]陆军工程大学国防工程学院,南京210007

出　　处：《传感技术学报》2017年第12期1850-1856,共7页Chinese Journal of Sensors and Actuators

基　　金：国家自然科学基金项目(51505499);江苏省自然科学基金项目(BK20150712)

摘　　要：为了准确分析反射型声表面波器件参数对其性能的影响,基于耦合模理论和P矩阵方法建立了器件的耦合模模型,分析得到器件的电反射特性即反射系数S11曲线,并在128°Y-X Li Nb O3压电基片试制了频率为90 MHz的多种参数的器件,分析与测试结果表明:单个叉指换能器器件的S11中心频率为91.26 MHz,幅值为-20.58 d B,与理论分析结果 91.44 MHz和-19.21 d B相近;带有反射栅的器件比单个叉指换能器件在中心频率处S11幅值增大约8.5 d B,谐振峰增多,时域曲线有明显的反射峰信号,验证了反射栅的反射特性;叉指换能器叉指对数减小使器件中心频率处的S11幅值减小,时域中的回波信号更尖锐,信噪比明显增大,表明对数较多的IDT具有较强的反射特性,对回波信号干扰较大,过小的叉指对数对器件声电转换效率影响很大,会使器件性能下降;较大的反射栅指条数对回波信号影响不大,但过小的指条数会降低反射栅反射系数,使得回波信号信噪比减小,纹波增多。In order to analyze the effect of the device parameters on the performance of the SAW（ Surface Acoustic Wave） reflective device,COM（ coupling of modes） model of SAW device was established by using COM and P matrix theory. Then,the reflective coefficients S11 of SAW device was deduced. Different parameters of SAW devices were designed and fabricated on 128° Y-X cut LiNbO_3 piezoelectric wafer. The conclusions are as follows. Firstly,the measured S11 results of single inter-digital transducer（ IDT） shows that the center frequency is 91.26 MHz and the amplitude is -20.58 dB,which matched well with the simulated results 91.44 MHz and-19.21 dB. Secondly,compared with single IDT device,the amplitude of the device with reflectors is greater 8.5 dB at the center frequency,and more resonance peaks in frequency domain and sharp peaks in time domain are presented. Thirdly,for the device with small IDT finger pairs,more resonance peaks in frequency domain and clear sharp peaks,larger signal-to noise ratio in time domain can be observed. This shows that the IDT with more finger pairs has stronger reflection property. Fourthly,when the electrode numbers of reflectors decreased,the signal-to noise ratio is decreased and the ripple is increased.The above conclusion can help researchers to optimize device parameters when designing SAW devices.

关 键 词：声表面波 叉指换能器 耦合模 反射系数 

分 类 号：TP212.3[自动化与计算机技术—检测技术与自动化装置]