旋涂法制备声表面波化学传感器膜的研究

声表面波化学传感器因高灵敏、便携而快速等优点被用来检测有毒有害气体。聚合物在声表面波敏感器件表面的旋涂技术是研究的热点。用旋涂法把溶于丙酮的氟硅氧烷聚合物溶液在声表面波器件表面制备成膜。通过网络分析仪,对在基片不同的旋涂区域和不同聚合物粘度对敏感芯片的品质因数和插入损耗的差异的分析、对比,确定环基片中心区为成膜的最佳旋涂区域,聚合物溶液增比粘度小于0.34时对成膜质量影响较小。     

Use of a surface-acoustic-wave (SAW) device to monitor etching of thin films

The use of a surface-acoustic-wave (SAW) device to monitor etching of thin films is described. The device is a delay-line-stabilized SAW oscillator in which the propagation path is coated with a thin film of the material to be etched. Removal of material decreases the mass loading on the delay line and this increases the frequency of the oscillator. The frequency of a 75-MHz oscillator is found to increase by more than 690 KHz for 1-µm decrease in film thickness. Using dual-oscillator arrangement, one can simultaneously monitor substrate temperature as well as thickness of material removed.     

声表面波延迟线振荡器为核心的气体传感器

声表面波(SAW)器件的工作频率随基片表面上的负载质量变化而发生漂移,通常利用这一性质作气相分析与检测,已经有了若干用SAW延迟线器件制成的化学传感器。传感器表面涂着一层有化学选择性的薄膜,这一涂层则在化学分析时有选择地吸收待测气体分子,涂层在吸收了气体后发生一些物理变化,因而这种传感器的灵敏度与SAW延迟线表面上的涂层对气体的吸收量有关。许多实际使用的传感器是用双SAW延迟线组成的,它们集成在一片基体上,并在一个延迟线表面上涂上气体吸附薄膜,而另一个则不涂任何物质。 本文讨论了这种传感器的若干问题,如温度影响、响应时间以及频率变化与气体浓度间关系的非线性。最后提出了在传感器应用时的改进方法与措施。     

Voltage-controlled SAW filter on berlinite

An electrically tunable narrow-bandwidth SAW filter described. This new device works similarly as a SAW voltage controlled oscillator. Because of stability requirements ar recent availability, experiments are reported on berlini (AlPO4) crystal.     

Integrated Circuit Compatible Surface Acoustic Wave Devices On Gallium Arsenide

Improvements in gallium arsenide materials technology have led to the rapid development of GaAs MIC, CCD, and digital IC technologies in the last several years. In this paper we consider the additional capabilities afforded by the inherent piezoelectric properties of GaAs. The primary emphasis of the work is on surface acoustic wave (SAW) device configurations using MESFET and Schottky-barrier diode fabrication techniques which are compatible with the eventual monolithic integration of electronic devices on the same substrate. The GaAs SAW technology described here provides a means for achieving electronically variable delay, high-Q resonator structures for VHF/UHF oscillator frequency control, and real-time signal processing operations such as convolution and correlation. Prototype device designs and performance are described, includlng two-port GaAs SAW resonators with Q's as large as 13 000 at 118 MHz and a programmable GaAs SAW PSK correlator capable of signal correlation at 10-MHz chip rates. Further GaAs SAW device development required for increasing the operating frequency range to 500 MHz and processing bandwidth to 100 MHz is indicated.     

The use of saw oscillators to suppress fm noise in local oscillators for on-board satellite applications

SAW oscillators can provide fundamental frequency operation to above 1·5 GHz, with stability and FM noise performance approaching that offered by bulk crystal oscillator technology. Their high fundamental frequency, small size and rugged construction gives SAW technology a unique capability at UHF and microwave frequencies. The low FM thermal noise floor associated with fundamental frequency operation can be combined with the stability and low close-to-carrier noise of multiplied bulk crystal oscillators by locking a high frequency SAW oscillator to a bulk crystal reference. SAW oscillator stability is compatible with conventional phase-locked-loop techniques and also with injection lock stabilization, and their own low close-to-carrier FM noise ensures that such locked sources exhibit minimum phase noise. Furthermore, locked oscillator phase noise is not significantly degraded when extreme operating conditions, such as those experienced in space applications, demand a reduced SAW device Q for reliable locking using either technique. Use of a PLL avoids any need for reference frequency multiplication, and provides additional design flexibility with respect to reference frequency selection and phase noise optimization. Injection locking offers design simplicity and uses fewer frequency control components, which can contribute additional noise in PLL sources.     

RF oscillator implementation using integrated CMOS surface acoustic wave resonators

This work is a proof of concept that a monolithic CMOS surface acoustic wave (SAW) resonator can function as an RF oscillator. The design of the oscillator includes the measurement characteristics of the CMOS SAW resonator, its matching networks, and RF amplifier is described. The integrated SAW resonator, with its operating frequency controlled by the spacing of its transducers was fabricated using a combination of CMOS plus post-CMOS processes. Based on the operation and performance of the SAW resonators, an equivalent circuit model of the CMOS SAW resonator was developed. A series resonant oscillator design was simulated using Microwave Office^TM. The designed matching network improves both the insertion losses and the phase slope of the resonator, while the RF amplifier provides sufficient gain to ensure oscillation. Measurements conducted on the RF-CMOS SAW oscillator demonstrated oscillation at 600 MHz.     

TV Tuning Systems with SAW Comb Filter

We have successfully developed two TV tuning systems which apply a SAW comb filter device in a new way. One is an automatic channel indicating system and the other is a frequency synthesizer. The SAW comb filter has comb peaks at the frequencies where channels are allocated. A channel number is recognized by counting the number of comb peaks which the local oscillator signal of a tuner goes through. The SAW comb filter has a minimum electrode width of 1 mu m. It has four sets of IDT's to cover all TV channels, fabricated on a single chip.     

SAW传感器及其在无源标识器中的应用

声表面波（SAW）器件作为信号处理器在现代扩频技术中已获得广泛的应用，推动了信号保密、抗干扰技术在通信、雷达、电子对抗等军用电子系统中的应用。然而，随着信息技术的深入发展，作为模拟技术的SAW技术，在信号处理领域依然展示着其实时强大的信号处理能力，同时在信息敏感方面也展现出卓越的优势，如其灵敏度高、直接频率和相位输出、多参量综合信号转换能力、性能稳定、无源低功耗、工艺简单且与半导体工艺兼容易于实现片上集成等特点，在多种物理、化学、生物传感器系统获得应用，广受重视。近年来，随着SAW器件工作频率提高到GHz以上，使得集信息敏感与信号处理、信号传输于一体的单芯片SAW无源标识器（SAW IDT）技术在多种SAW传感器系统获得广泛的应用，成为当今SAW和传感器两个技术领域的一个新发展亮点。本文基于信息敏感的角度对SAW传感器的理论、设计、结构、系统研究方向，在无源标识器（IDT）应用军方面进行了探讨。     

Composite substrate material for surface acoustic-wave oscillator

Surface acoustic-wave (SAW) oscillators have advantageous features compared with other technologies. The Y-128° LiNbO₃ is a well-known, high electromechanical-coupling SAW material, but its usefulness is limited because of its poor temperature-stability property. The AlN films have some excellent characteristics, such as high SAW velocity, stable chemical properties, and high-temperature stability. In this research, different thickness AlN films were sputtered on Y-128° LiNbO₃ to be a composite substrate for the SAW oscillator. As AlN film thickness increased, the temperature coefficient of frequency (TCF) value of the oscillator varied from −76.32 ppm/°C to −28.81 ppm/°C giving an improvement in the TCF of 62.25%. The oscillator frequency at 25°C also varied from 40.0909 MHz to 41.6221 MHz, giving an improvement in the oscillator frequency of 3.8%. The composite substrate (AlN/Y-128° LiNbO₃) can enhance the oscillator frequency and effectively improve the poor temperature stability for the SAW oscillator.     

一种新型多反射栅声表面波化学量传感器的研究

提出了一种新的延迟线型声表面波化学量化传感器,作为敏感组件的声表面波器件由１组叉指换能器和多个反射组成,经过高频调制的脉冲信号通过叉指换能器在器件表面激励起声表面波,遇到反射栅发生反射,反射回来的声表面波面由叉指换能器转化成电信号。Ｎ个反射栅即可形成Ｎ个反射脉冲,通过测量各个反射脉冲之间的传输时间,即可实现对相应各反射栅之间表面状态的检测,当各反射栅之间制备有化学敏感膜时,即可实现新型化学量传感器     

SAW Oscillators In UHF Transit Satellite Links

A 375-MHz surface-acoustic-wave (SAW) resonator controlled oscillator was developed for application in the Transit satellite marine navigation system. The SAW oscillator, in a 2-in/sup 3/ hybrid package, contains a heater, voltage regulator, and divider and is a direct replacement for a bulk wave oscillator and its multiplier chain. A short term stability of 2E - 10 and an aging rate of 3E - 8/day were achieved at 75°C. Comparison tests showed that the accuracy of the navigation system with the SAW oscillator was equivalent to the accuracy using the bulk oscillator.     

具有PDEB LB膜的声表面波湿度传感器

介绍一种新型聚炔离子导体湿敏材料－聚对二炔苯的Ｌａｎｇｍｕｉｒ－Ｂｏｌｄｇｅｔｔ成膜原理与制备，淀积有１０层ＰＤＥＢ ＬＢ膜层的声表面波延迟线型湿度传感器的特性。由于ＬＢ成膜技术拉制的膜可以在分子水平上进行定量控制，保证了膜的均匀性和一致性。     

一种便携SAW气体传感器的电路设计

该文采用信号处理技术,设计了一种振荡电路。该电路解决了双延迟线型声表面波(SAW)器件不易起振,频率跳变等问题。整个电路结构简单,对插损低于20 dB的器件有很好的起振效果,满足气体检测的需要。     

A Radar System Application of an 840-MHz SAW Resonator Stabilized Oscillator

An 840-MHz SAW resonator stabilized oscillator has been developed and is being manufactured for incorporation into a radar system. This stable fundamental-mode frequency source is simple and compact (1 in/sup 3/ in volume) and delivers a relatively high output power of +25 dBm. These advantageous characteristics are made possible by the high-frequency low-loss distortion-free/linear-phase response of the two-port SAW resonator filter incorporated in the design. Details of the device and circuit design and oscillator performance are presented.     

State of the art in wireless sensing with surface acoustic waves

Surface acoustic wave (SAW) passive devices can be used in novel applications such as wireless identification and sensing. For identification purposes, a SAW transponder picks up an electromagnetic request signal and stores it until all echoes caused by multipath propagation have died away. Then, a characteristic response is beamed back to the receiver. In radio-link sensors, a physical or chemical quantity influences the propagation properties of the SAW and consequently changes the response pattern of the device. This paper surveys the operating principle of such sensors and their state-of-the-art performance. Examples include temperature sensors and sensors for mechatronic applications     

Reference SAW oscillator on quartz-on-silicon (QoS) wafer forpolylithic integration of true single chip radio

The authors present an electro-acoustic circuit fabricated on quartz directly bonded on the processed silicon wafer (QoS), which allows us to polylithically integrate high precision passives with integrated circuits. We first fabricated a prototype SAW resonator and oscillator on thick QoS. The SAW resonator on QoS shows Q about 10,000 and 11 dB insertion loss at 289 MHz, and SAW oscillator on QoS shows phase noise of as small as -120 dBc at 100 kHz offset, demonstrating the feasibility of true single chip radio     

A charge-flow transistor oscillator circuit

The charge-flow transistor (CFT) turn-on delay time can be monitored with a two-inverter one-latch oscillator. Data are presented for a CFT oscillator incorporating the moisture-sensitive polymer film, poly (p-aminophenylacetylene). An instability of oscillator period is observed in certain bias conditions. The origin of this instability is shown to be charge-averaging the polymer film. The averaging time, which can be extracted from the transient behavior of the oscillator period after power-up, is identified as the bulk dielectric relaxation time of the polymer, and equals 130 s in the present case. A theory of oscillator operation that accounts for the observed behavior is presented, along with a brief illustration of the use of such devices in sensing applications.     

Development of a GaAs monolithic surface acoustic wave integratedcircuit

An oscillator technology using surface acoustic wave (SAW) delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. The oscillator consists of a two-port SAW delay line in a feedback loop with a four-stage GaAs MESFET amplifier. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. This oscillator technology is most suitable for sensor applications but can logically be extended to radio-frequency oscillator and filter applications by methods well known for other piezoelectric substrates