Low insertion loss and good temperature stability are the main requirements for
filters used in communication system front ends. These requirements severely limit the design
options for SAW filters that can be used in modern communication systems. It should be noted
that until recently SAW filters with a relative bandwidth of 1..10% and low losses, and most
demanded for communication systems, had low-temperature stability. This was due to the
temperature coefficients of waveguide material medium frequency of the SAW filters. Such
materials are strong piezoelectrics niobate and lithium tantalate.
Research aimed at improving the temperature stability of devices based on lithium niobate and
tantalate was started a long time ago. Still, only emerging new technologies have provided the
possibility of solving this problem for mass production conditions. Currently, the input circuits
of almost all mobile communication devices incorporate filters (duplexers) on SAW.
Keywords: Acoustoelectric circuit, Bandwidth, Communication devices, Duplexer, Electromechanical coupling coefficient, Filter, Lithium niobate, Measurements, Surface acoustic wave, Transducer.
