微波体声波延迟线的电磁屏蔽

本文分析了微波体声波延迟线多层介质的电磁屏蔽效应，结果表明，全屏蔽方式可以有效地解决微波延迟线研制中的直通抑制问题。实验结果证实了理论分析。     

GaPO4 high temperature crystal microbalance demonstration up to 720°C

Quartz-homeotypic gallium (ortho-) phosphate, GaPO₄, is of special interest for resonator applications asking for temperature compensated cuts with higher electro-mechanical coupling than quartz and operational temperatures up to 970°C. The crystal microbalance technique, well known for quartz (QCM) which can be used only at moderate temperatures, can now be extended to much higher temperatures using GaPO₄ crystals, benefiting from all three advantages mentioned above. Two different experiments were done to demonstrate the advantages of a crystal microbalance based on GaPO₄. First, the GaPO₄ resonator was used for film thickness determination and compared with a commercial QCM. This experiment demonstrated that the measuring range can be extended by using GaPO₄ resonators instead of quartz. The second experiment demonstrates the possibility for thermogravimetric analysis up to 720°C by using a new concept for resonator mounting.This revised version was published online in November 2005 with corrections to the Cover Date.     

Parametric model of the BAW resonator phase-noise

Excepted for the very short terms the frequency stability of ultra-stable oscillators is mainly limited by the resonator noise. In this work we proposed a parametric model of the bulk acoustic wave (BAW) resonator phase noise based on an equivalent circuit. This model explains phase noise generated by a BAW crystal from a point of view of parametric fluctuations and proves the f⁻¹ dependences of the crystal noise. The model performance is verified with simulation. Simulation results are compared to experimental data and discussed. Comparison of three existing models is made.     

Integrated approach to electrode and AlN depositions for bulk acoustic wave (BAW) devices

This paper investigates the (002) texture of AlN films deposited by reactive pulsed direct current sputtering on Al, Al–Cu, W and Mo metal electrodes. X-Ray diffraction and atomic force microscopy studies show that the AlN texture is dependent on the deposition conditions and nature of the underlayers. A smooth underlayer with a sharp texture represents the best combination of properties. AlN films with a full width at half maximum less than 1.5 have been deposited on the electrodes studied. It is also possible to deposit well-textured electrodes with a roughness less than 2.5 nm.     

Ion chromatographic determination of salicylate in human serum with a bulk acoustic wave sensor as detector

Salicylate is a hydrolysis product of salicylate-containing drugs (such as aspirin) in patients' blood. Monitoring of this ion in blood is helpful for diagnosing of overdosage of these drugs. The present paper describes an ion chromatography (IC) method developed for determination of total salicylate in human serum, in which a hulk acoustic wave (BAW) sensor was used as detector; 0.5 mmoI/L sodium carbonate (Na₂CO₃, pH 8.5) served as mobile phase. Interference in the determination was negligible. The method is simple, rapid, accurate, and precise. Serum salicylate was analyzed using both the proposed IC-BAW method and the classical Trinder spec-trophotometric method, and the results showed that the two method agreed well.     

一种新型声表面波振荡器系统的设计研究

针对振荡器中声表面波器件存在的体声波干扰、电极反射及旁瓣过大问题,提出了一种新型声表面波振荡器系统的设计方案。该方案将多条耦合器用于分离体声波,分裂电极用于减弱电极反射问题,并采用了输入、输出换能器双加权的措施来降低旁瓣信号。通过对一个中心频率为50.8MHz声表面波振荡器的实现和测试,得到该新型声表面波振荡器系统的振荡频率为50.613 MHz,与系统的设计值误差仅为3.6‰,并且具有良好的周期性和稳定性。     

Balanced RF Duplexer with Low Interference Using Hybrid BAW Resonators for LTE Application

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long‐Term Evolution band‐7 duplexer should be designed to prevent the co‐existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice‐ and ladder‐type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance‐to‐unbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as 2.0 mm × 1.6 mm. The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to ?16.9 ppm/°C.     

基片开槽抑制SAW滤波器体声波的工艺研究

当叉指换能器在基片上激励声表面波模式时，同时伴随着体声波的激励。文章根据叉指换能器的激励原理，采取对压电基片背面开槽抑制叉指换能器体声波进行了实验研究。分别在ST、LT、LN压电基片上背面开槽并制作了中心频率为28MHz、70MHz、71MHz、120MHz声表面波滤波器。实验观察了体声波的抑制情况，并得出了具体实验数据。     

基于NbN，AIN技术的体声波器件研究

体声波滤波器由于其低插损、小尺寸、高带外抑制等特性，随着第三代移动通信以及蓝牙技术的发展而得到广泛研究，而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能．我们以单晶MgO作为器件衬底，MgO/NbN多层结构作为AIN薄膜体声波器件的反射器，NBN／AIN／NbN三层结构为谐振器．在这样的多层结构的设计中由于各种材料之间的晶格失配小，可以获得从几十纳米到几百纳米厚度不等的单晶AIN薄膜．通过控制AIN薄膜和NbN薄膜的不同厚度，可以获得不同频段范围的谐振器．压电薄膜的质量，以及体声波在多层结构界面上的能量损耗，直接影响到谐振器电学性能．基于AIN材料的压电性能，设计了NBN／AIN／NBN三层结构的谐振器，并进行了数值模拟．     

声体波延迟线在电子战中的应用

讨论了用声体波延迟线实现准相干诱饵的一种方式,阐述了其对声体波延迟线的参数要求。