Practical surface acoustic wave devices

A tutorial discussion is presented on selected surface acoustic wave (SAW) devices for the use of engineers and electronic systems designers. Currently practical components for use in radar systems, communications systems, and as frequency domain filters are described. Emphasis is placed on nondispersive and dispersive delay lines, devices for generating and detecting various radar waveforms, devices for generating and detecting fixed and programmable biphase and multiphase codes, and broad-band and narrow-band filters. The device possibilities of several new approaches are described, including multistrip couplers, nonlinear convolvers, reflective structures, and overlay films. It is concluded that, while SAW devices have found many applications in large radar systems because of their size, cost effectiveness, and reliability, wide-scale applications, for example as frequency domain filters, will be needed to justify continued research in this field. Wide-scale applications will come as systems engineers realize the potential of these devices and confidently design them into their systems.     

Surface Wave Device Applications in Microwave Communication Systems

The application of certain prototype devices, already realized in the complementary surface acoustic wave (SAW) and magnetostatic wave (MSW) technologies, is examined in the context of analogue and digital microwave communications equipments. The specifications of Gaussian response IF bandpass filters and satellite channel multiplexing filters are detailed in the context of SAW designs. Extensions of SAW filter technology to the construction of IF remodulating modems incorporating frequency modulated oscillators and discriminators are examined. Stable SAW oscillators are also reviewed in the context of lightweight, rugged, spacequalified local oscillator drives. The application of MSW technology to the design of a group delay equalizer for millimetric waveguide long-haul digital communications equipments is surveyed. Finally, the paper addresses the design of fixed and variable delay lines realized in both technologies, and SAW code generators, for application to path-length equalization and test{ng of high data rate microwave radio relay systems, respectively.     

声表面波VCO的研制

介绍了１５５．５２ＭＨｚ、６２２．０８ＭＨｚ声表面波（ＳＡＷ）、１２４４．１６ＭＨｚ浅体波（ＳＴＷ）压控振荡器（ＶＣＯ）的原理、设计和性能。采用低插损、高Ｑ值的ＳＡＷ延迟线和ＳＴＷ谐振器，高性能微波放大器，变容二极管电移相器，使振荡器具有非常低的相位噪声（＜－１４０ｄＢｃ／Ｈｚａｔ１００ｋＨｚ）、高输出功率（＞９ｄＢｍ）、低温度－频率漂移（＜±３５ｐｐｍ，温度范围：－５～６０℃）、大频率调谐范围（＞４００ｐｐｍ）。     

The theory, design, and applications of surface acoustic wave Fourier-transform processors

This paper addresses the theory, design, and applications of surface acoustic wave (SAW) Fourier-transform processors. These analog processors are shown to perform several sophisticated real-time signal-processing functions at wide bandwidth (tens of megahertz) making them attractive for use in radar, sonar, and communication equipments. Theoretical results show how specific arrangements of physically realizable SAW chirp filters permit Fourier transformation of both baseband and IF input signals. The operation of SAW Fourier-transform processors, with separate real- and imaginary-baseband inputs, highlights their use as wide-band "FFT-type" processors. The application of individual SAW-based processors to spectrum analysis, network analysis, beamforming, and frequency-hopped wave-form synthesis is discussed and demonstrated. Finally, the use of combinations of two or more SAW Fourier-transform processors for cepstrum analysis and programmable correlation is described.     

Magnetostatic wave devices for UHF band applications

Magnetostatic surface wave (MSSW) devices made with pure and gallium-substituted yttrium-iron garnet (Ga:La-YIG) films are described. These devices include nondispersive and dispersive delay lines, band-pass filters, oscillators, and resonators. By controlling the magnitude of the bias magnetic field and the temperature of operation, it is possible to tune these devices over a wide frequency range extending from 0.3 to 4 GHz and from 3 to 18 GHz using Ga:La-YIG and pure YIG films, respectively.These devices could be used in pulse compression radar, microscan receivers, complicated Fourier transform processors, and fundamental oscillator circuits. In this paper, we briefly show results for pure YIG devices tunable in C and X bands and discuss, in detail, the performance of the Ga:La-YIG devices for UHF applications.     

Microwave acoustic materials, devices, and applications

This paper surveys applications of acoustic waves in microwave devices. After a general and historical introduction to bulk acoustic waves (BAWs), surface acoustic waves (SAWs), practical wave types, and acoustoelectric transducers, a review is given of technologically important materials for microwave acoustic applications. Following this, we discuss BAW and SAW microwave devices and their technologies. Specifically reviewed are thin-film resonators and filters, transversal filters, and filters for correlative analog signal processing. Finally, an overview of the most important microwave applications is given, along with manufacturing and packaging issues     

System applications of magnetostatic wave devices

A need for microwave signal processing components ranging from simple delay lines to broadband, complex analog non-recursive transversal filters has led to the exploration of several solid-state technologies. Bulk acoustic delay lines lack spatial signal tapping and have high insertion loss. Electromagnetic delay lines have high insertion loss, limited signal processing capabilities, and are bulky. Surface acoustic wave (SAW) devices offer excellent signal processing capabilities at VHF/UHF but suffer from excessive loss at microwave frequencies and the requirement for transducers of sub-micron linewidths. However, a signal processing technology based on magnetostatic waves (MSW) propagating on epitaxial yttrium iron garnet (YIG) is emerging to fill microwave signal processing requirements. This paper summarizes the characteristics and status of magnetostatic waves and devices based on MSW, and initial experimental studies of the application of MSW devices to systems, and presents a survey of other potential areas of MSW device applications.     

Surface-acoustic-wave devices for signal processing applications

A survey of SAW devices is presented including delay lines, frequency filters, oscillators, matched filters, and Fourier transformers. Application of these devices to signal processing is discussed.     

Implementation of Satellite Communication Systems Using Surface Acoustic Waves

Current performance of surface-acoustic-wave (SAW) devices offers several advantages in the construction of digital communication networks. Experimental examples of delay lines, filters, oscillators, etc., used for the modulation, the frequency conversion, and the demodulation of n-phase-shift-keyed (PSK) digital signals are described and present results are reported. These devices, especially designed for satellite communication systems, operate in the range 70 MHz to 1 GHz where the surface wave technology allows reduction in size and weight combined with ruggedness and reliability.     

A surface acoustic wave delay line phase amplifier

Theoretical analysis of surface acoustic wave (SAW) delay line resonators is extended to show the possibility of a novel circuit, which can be used to amplify the phase shift of a fixed frequency signal associated with an electronic circuit.     

Properties and applications of reflective-array devices

The use of reflective arrays in surface-wave devices has yielded new devices such as resonators in addition to an enlarged parameter range for devices such as radar pulse expanders and compressors. A number of different grating geometries, substrates, and types of reflectors have been employed in resonators, band-pass filters, filter banks, oscillators, and dispersive delay lines. Simple, yet accurate, models have been developed for design and analysis of reflection gratings in these applications. The major application of reflective arrays has been in radar pulse compressors wherein low spurious levels and precise phase and amplitude response have been achieved in devices with time-bandwidth products as large as 10⁴. Other signal-processing applications such as chirp-z transforms can exploit the large time-bandwidth products available in reflective-array devices.     

Wireless identification and sensing using surface acoustic wave devices

Today Surface Acoustic Wave (SAW) devices are used in many electronic products, e.g. as filters in communications applications or for signal processing in radar systems. Due to the dependence of the propagation characteristic of the microacoustic wave on many physical parameters (e.g. temperature or strain) it is possible to build SAW sensors for a great variety of physical, chemical and biological parameters. SAW sensors are not only small, rugged and show small aging rates, they also can be used as wirelessly interrogable and completely passive sensors for many hostile environments. In this contribution the SAW device principles, design procedures and technological issues as well as examples of their use in certain measurement and identification applications are reviewed.     

GHz频带声表面波谐振器的研究

本文叙述了GHz频带声表面波谐振器的设计、制造和试验结果.对两种不同模式的声表面波谐振器进行了研究,它们是瑞利波型谐振器和表面横波型谐振器.对两种波型谐振器的频率温度特性进行了比较.最后对表面横波(STW)谐振器在振荡器中的应用进行了研究.     

压电和铁电薄膜及其应用的发展趋势

本文讨论了压电和铁电薄膜材料及其在固体器件中应用的发展趋势。薄膜生长技术的进展,为压电和铁电薄膜集成固体器件在各个领域的应用开辟了广阔的前景。ZnO和AIN薄膜将广泛地用于SAW和BAW器件。特别是成功地制作了薄膜体声波谐振器和高次谐波体波谐振器。以PbTiO_3为基的PZT和PLZT固溶体外延薄膜将应用于热电探测器和SAW器件。在实现了对多层薄膜的界面结构及其特性的成功控制之后,铁电薄膜将在铁电存储和集成光学领域发挥重要作用。     

Magnetostatic wave technology: a review

Magnetostatic wave (MSW) technology has been under investigation for more than a decade. Using ferrimagnetic films such as liquid-phase epitaxial (LPE) yttrium iron garnet (YIG) films, MSW devices and subsystems offer instantaneous bandwidths of up to 1 GHz at operating frequencies in the microwave bands (0.5-26.5 GHz). Because MSWs travel with velocities two-to-four orders of magnitude slower than electromagnetic waves, compact devices can be built using hybrid and monolithic microwave integrated circuit (MMIC) techniques. These devices include delay lines, dispersive delay lines, filters, resonators, and directional couplers. Subsystems using these devices, such as electronically tunable delay lines channelized filter banks, delay-line discriminators, oscillators, and frequency multipliers can be used for applications in signal identification, control and processing directly at microwave frequencies. An overview of the MSW technology is presented and an assessment of the various devices and subsystems that can be built using thin and thick LPE-YIG films is provided     

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.     

High-Q microwave acoustic resonators and filters

The authors present recent experimental and modeling results for high-Q microwave acoustic resonators and filters for use in oscillators and other frequency control applications. Overmoded resonators have exhibited an FQ product greater than 1×10¹⁴ Hz (e.g., Q=68,000 at 1.6 GHz) with a strong inductive response suitable for one-port and two-port oscillator feedback circuits. Ladder filters fabricated with overmoded resonators have loaded Qs greater than 40,000 with 76-kHz bandwidth at 1.6 GHz. Aluminum nitride films were used for transduction on Z-cut sapphire and lithium niobate substrates     

SAW Filters Composed of Interdigital Schottky and Ohmic Contacts on AlGaN/GaN Heterostructures

We proposed surface acoustic wave (SAW) filters composed of interdigital Schottky and ohmic contacts on AlGaN/GaN heterostructures. The contribution of the SAWs appeared in the radio frequency characteristics of the filters when the Schottky contacts were reverse biased. Onsets of the SAW signals and the threshold voltage of simultaneously fabricated high-electron mobility transistors were found to almost agree with one another. We also obtained an isolation of >40 dB. These results suggest that SAW-based functional devices are likely to be realized using AlGaN/GaN heterostructures with interdigital Schottky and ohmic contacts     

Lithium iodate—A new material for surface acoustic wave applications

Lithium iodate (LiIO3) is proposed as a new material for possible use in surface acoustic wave (SAW) devices. The variation of the SAW velocity, an estimate of the electromagnetic to acoustic coupiing (Δv/v), the temperature coefficient of delay (TCD), and the power flow angle have been theoretically predicted for the standard crystallographic cuts. This material is shown to have more than 1.5 times the coupling of LiNbO3, SAW velocities only slightly higher than Bi12GeO20, low temperature coefficients of delay, and low power flow angles.