| With the superiority on compactness, repeatability, performance and mass producibility, surface acoustic wave (SAW) filters have been widely adopted in equipment related to communication, navigation, wireless data transmission as well as audio and video electronic products for filtering unwanted signals.With the boom of mobile communication, multi-mode and multi-band 3G handsets create large needs for SAW filters and duplexers, attracting intensive research and development of wideband and low loss SAW filters.Content of this dissertation covers fundamental theories, designs, fabrication and measurement technologies of SAW filters as well as impact of SAW filters on circuit performace. In addition, simulation, fabrication and measurement of SAW filters and resonators were conducted, the main work is as follows.SAW transversal filters of 500 MHz central requency with small group delay variation by adopting single phase unidirectional tranduders were fabricated, ZnO/IDT/Diamond structure was produced for high SAW velocity and was applied to a 5 GHz SAW filters fabrication.Resonator design was discussed by couple-of-mode analysis and simulation, resonators were fabricated and spurious modes in resonators were studied. With length and width weighted dummy electrodes adopted for suppression of spurious modes, SAW filters of ladder-type structure were fabricated for central frequency of 940 MHz, 1 GHz, 1.8 GHz respectively.A laser probe system for visualization of SAW distribution was improved, data acquisition of 2620(x)×410(y) points in 20 min. is realized, better quality image can be reconstructed from the processed data by removing spurious due to electromagnetic feedthrough and optical reflection variation in wavenumber domain.Impact of reflection coefficient of SAW filters on amplifiers was investigated, suppression by using quadrature hybrids was suggested and validated by microstrip and lumped elements configration, respectively.
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