Low-loss SAW Filters using new SPUDT structures

The new SPUDT structures based on triple electrode sections (TES) per wavelength with the period between SAW sources about nl/3 are presented. The simulation technique which accounts for second order effects has been developed within the framework of modified equivalent circuit model. The SPUDT structures have been implemented in filters with 0.1-3.2% bandwidths fabricated on […]

SAW filters with very high shape factor

Transversal filters with very high shape factor have been developed based on multiharmonic and withdrawal weighted transducers with isolated sections. The developed simulation technique provides excellent  results both for in-line filter structures and those with  multistrip couplers. The experimental results are presented for IF filters manufactured on YZ-LiNbO3  and ST-quartz substrates. In-line filters exhibit SF […]

Wideband low loss SAW filters for telecommunication and mobile radio applications

The possibility of utilizing cuts of LiNbO3 with high piezoelectric coupling for leaky waves - 41°-YX and 49°-YX - in wideband SAW filters, has been demonstrated. The equivalent circuit model was modified for longitudinally coupled resonator filters and some second-order effects have been taken into account to improve the accuracy of filter simulation. Thick Al electrodes are used to increase the […]

Lower-loss Filters on Langasite

The advantages of langasite as a substrate material for SAW filters are not realized entirely till now because of the natural unidirectivity of most cuts available for practical applications. This paper presents new results that allow the utilization of langasite for SAW filters. The mathematic model, SPUDT cell structures and design method were developed for naturally unidirectional orientations. This approach allows designs […]

Single Port SAW Resonators Design

This work deals with some aspects of resonator performance improvement on unidirectional substrates with arbitrary reflection angle. A design concept is proposed based on the use of resonators with slight (by about 1-2%, depending on the material properties) frequency increase (or decrease, for opposite phase) of the IDT pitch in the transducer center for bi-directional substrates. For naturally unidirectional orientations properly […]

Low-loss slanted SAW Filters with low shape factors

This paper describes SAW filters based on quasi-slanted transducers. Stepped electrodes structures used  for  such filters realization provide decreasing of filter shape factor and simplify their performance. Experimental  results  of the filters with relative bandwidths from 2 % to 70 % are represented. INTRODUCTION SAW filters based on slanted or tapered transducers have  been  under […]

Design of SAW Filters on Langasite

Due to good temperature stability and moderately high electromechanical coupling coefficient langasite (Li3Ga5SiO4 or LGS) is known as a promising material for SAW devices. The characteristics of the Rayleigh wave propagation on LGS have been studied fairly well. However, no design of SAW devices on LGS suitable for modern communication systems has been reported as […]

RSPUDT Filters based on different width split fingers

RSPUDT filters based on different width split fingers for IF applications have been developed. Such filters provide improvement of insertion loss comparing to DART-RSPUDT filters. A new optimization procedure for RSPUDT filter design has been proposed, based on the adjustment of RSPUDT through a synthesis grid of narrow structure elements. The width of these elements is equal to or smaller than a […]

Novel structures for low-loss slanted Filters

New structures of slanted transducers are described. These structures are based on a variation of weighting along a filter aperture. The first quasirectangular structure has equal lengths but different numbers of fingers for every frequency channels. The second partially-weighted transducer comprises with different weighting for lateral and central frequency channels. The use of such structure allows to improve some filter parameters, such as […]

Applocation of SAW – Filters in the ethereal Television Systems in the city conditions

Abstract - The results of investigation and practical application of "low-loss" filters on surface acoustic waves (SAW) in ethereal collective television systems in city conditions are given. Use of the circuit of channel amplifiers in which frequency selectivity is carried out by the high-frequency SAW- filters included on an input and an output of the […]