Frequency demodulator for DBS using an SAW adaptive filter

A frequency demodulator for DBS using an SAW adaptive filter is described. It gives quasioptimal performance with the D2-MAC/packet system and can also be useful with C-MAC/packet when a single FM demodulator is used. The SAW device is described and experimental results arc given     

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.     

New low-loss broadband SAW filter using unidirectional IDTs with U-shaped MSCs

A new low-loss broadband SAW filter is presented. A new configuration using one pair of electrically connected IDTs with an optimum number of fingers, as well as unidirectional IDTs with U-shaped MSCs, is described. Experimental results with bandwidth as wide as 10% and loss as low as 3 dB are achieved. Very accurate computer-aided design of a low-loss filter with MSCs is obtained.     

Low-loss SAW filter using internal reflection types of single-phase unidirectional transducer

A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the change of the electromechanical coupling coefficient within a half or one wavelength is described.     

Thermosonic flip-chip bonding for SAW filter

A flip-chip bonding (FCB) method suitable for the surface acoustic wave (SAW) filter was developed. In this method, the gold-ball bumps formed on the chip are directly bonded onto the ceramic substrate by thermosonic bonding. After FCB, they are sealed with a cap without using underfill resin. To obtain high bond strength, characteristic properties of the substrate electrode and the ball bump, were optimized. Furthermore, bondability has been improved by adopting a ramp-up loading profile. The reliability test was carried out with 6-pin SAW chips, and we confirmed the sufficient reliability of bonds.     

Narrow-aperture SAW filter with both transducers finger-length-weighted

A 2.5 ?-aperture SAW filter has been designed and tested. The single-mode nature of the waveguiding filter allows finger-length-weighting to be distributed between input and output transducers according to a simple procedure. The resulting filter has a stopband rejection in excess of 50 dB.     

SAW chirp filter performance above 1 GHz

The performance of a practical compact SAW dispersive filter with a bandwidth in excess of 500 MHz and centered at 1.3 GHz is described. The linear FM chirp filter was fabricated and serially reproduced by electron-beam microfabrication. The effect of an externally implemented weighting function on the time domain performance is discussed. The filter has been found suitable for pulse compression in a high-resolution monopulse radar. Replication of filter sets with identical characteristics is discussed.     

Gigahertz signal processing using reflex optoelectronic switching matrices

The application of reflex optoelectronic switching matrices (ROSM) to signal processing in the gigahertz region is analyzed. Various signal processing functions such as delay generation, loop filtering, word generation/detection, integration, and digital to analog conversion are identified and their respective realizations in a ROSM are presented. It is found that for dedicated signal processing functions, simpler submatrices instead of full matrices can be employed with significant reduction in complexity and cost. The performance of ROSM's using currently commercially available components confirms the feasibility of gigahertz signal processing with ROSM's.     

New low-loss SAW filter using internal floating electrode reflection types of single-phase unidirectional transducer

A new single-phase unidirectional transducer utilising the difference between excitation and reflection positions caused by the floating electrodes of open and short metal strips inserted into the interdigital transducer within a half wavelength is described.     

FIR digital filter design techniques using weighted Chebyshev approximation

This paper discusses the various approaches to designing FIR digital filters using the theory of weighted Chebyshev approximation. The different design techniques are explained and compared on the basis of their capabilities and limitations. The relationships between filter parameters are briefly discussed for the case of low-pass filters. Extensions of the theory to the problems of magnitude and complex approximation are also included, as are some recent results on the design of two-dimensional FIR filters by transformation.     

Piezoelectric thin film unidirectional SAW transducer and filter

Small passband ripple piezoelectric thin film unidirectional transducers and filters are presented. ZnO thin film deposited on a fused silica was used in the experiment. As the result, the characteristics of no pass-band ripple and minimum insertion loss of 5.2 dB, and also the directionality of 22 to 29 dB per one transducer are obtained.     

Fabrication of submicrometre resist patterns using an edge-defined technique

An edge-defined technique for the fabrication of submicrometre resist patterns is described. The technique consists of resist pattern fabrication, deep UV hardening, plasma deposition, spin coating of resist, developing back, and wet etch. A 100 nm line in 1.2 ?m-thick resist layer is obtained with essentially vertical walls.     

圆形IDT结构声表面波滤波器的设计与实现

采用硅基AlN薄膜作为压电衬底,利用改进的δ函数模型对变迹加权圆形IDT结构进行建模仿真,根据仿真结果设计SAW带通滤波器版图,并在实验室制作了中心频率为300 MHz,带内插损8 dB的SAW带通滤波器样品。测试结果表明,其仿真结果与试验结果一致性较好。     

Positive/negative reflection-type SAW reflectors on ST-quartz using new fabrication technique

A positive/negative reflection-type (PNR) SAW grating reflector on an ST-quartz substrate utilising both a gold and aluminium strip and its simple fabrication technique requiring no critical mask alignment are described.     

A 44-MHz wideband switched-capacitor bandpass filter using double-sampling pseudo-two-path techniques

A fully differential wideband sixth-order switched-capacitor bandpass filter is designed for channel selection in cable TV applications. A modified double-sampling pseudo-two-path technique is proposed to achieve a second-order wideband bandpass filter with a single opamp. Implemented in a standard double-poly four-metal 0.35-/spl mu/m CMOS process and operated at 176-MHz sampling frequency, the filter achieves a measured center frequency of 44 MHz with a bandwidth of 6.28 MHz and a dynamic range of 58.3 dB at 3% IM3. The filter consumes 92.5mW at a single 3.0-V supply and occupies a chip area of 0.52 mm /sup 2/.     

Design and performance of a SAW ladder-type filter at 3.15 GHzusing SAW mass-production technology [wireless LANs]

To meet the increasing demand for high-performance filters in gigahertz radio-communication systems, we have improved the design techniques and fabrication processes for surface-acoustic wave (SAW) devices. The standard optical projection printing technique based on i-line lithography used for mass-production was optimized, thus attaining a linewidth of 0.3 μm. As a first SAW device prototype, we designed and fabricated a ladder-type bandpass filter from LiTaO₃ substrates, at 3.15 GHz having a 3 dB-bandwidth of 128 MHz and a minimum insertion loss of 1.7 dB     

A new compact LTCC bandpass filter using negative coupling

This letter presents the design and realization of a new compact bandpass filter (BPF) fabricated on multilayered ceramic substrates. This BPF features coupled resonators with negative coupling coefficients. A BPF with center frequency 2.45 GHz is designed and fabricated. Its size is only 2.0 mm/spl times/1.8 mm/spl times/0.67 mm when implemented by a standard low temperature co-fired ceramic technology. The size reduction is due to the higher coupling coefficient between the negatively-coupled resonators than the positively-coupled ones, allowing tighter space between the resonators. The measured insertion losses of the previous BPF were less than 3dB and return losses more than 18dB in the passband. The measured result agrees very well with the electromagnetic (EM) designed response.     

Low-distortion switched-capacitor filter design techniques

The distortion mechanism in switched-capacitor (SC) filters are considered, and closed-form expression relating switched-capacitors filter distortion to circuit parameters are derived. Design techniques for low-distortion applications are discussed and are applied to a sixth-order experimental filter. The filter design uses a fully differential class A/B op amp with a continuous-time common-mode feedback circuit. Distortion measurements show that for 82-dB dynamic range (relative to noise floor) the total harmonic distortion of 0.02% within the whole 4-kHz bandwidth and 0.07% within 20-kHz bandwidth.     

近表面加工技术制备的高性能Ge:B 阻挡杂质带探测器

阻挡杂质带（BIB）探测器是当前远红外天文探测领域的主流探测器。通过近表面加工技术成功制备出了高性能的Ge:B BIB探测器,响应波数范围从50 cm^-1到400 cm^-1。在3.5 K温度和30 mV工作电压下,器件在峰值响应84.9 cm^-1处的响应率达到21.46 A·W^-1,探测率达到4.34×10¹⁴cm·Hz^1/2·W^-1。研究了BIB探测器中界面势垒对响应光谱的影响。提出了一种新的激发模式—电极区内的载流子可以通过光激发的方式越过势垒。此外,还发现了一种增强BIB探测器在小波数处相对响应强度的方法。     

Miniature SAW device using MEMS technology

A miniature SAW device is designed and fabricated at 1 GHz for wireless communication system. A 5 μm thin film of ZnO is successfully deposited using RF sputtering technique on plasma-enhanced chemical deposition (PECVD) SiO₂ layer of 1 μm on top of Si wafer under various operating conditions. The c-axis-oriented ZnO film exhibit a sharp diffraction peak corresponding to the (0 0 2) reflection at 2θ=34.42. The fabrication process utilizing the micro-electro-mechanical systems (MEMS) technology of the SAW device is described. Simulation of the RF-SAW filter is performed. Measurements and experimental work are presented for the RF-SAW device.