S.A.W. filters - Some case histories

The design of surface acoustic wave (SAW) filters is reviewed and the application of SAW design criteria is illustrated by three case histories. Consideration is given to the problem of determining the finite impulse response of a SAW transversal filter which gives a frequency response meeting specifications, and of implementing the impulse response as accurately as possible, taking into account electrode effects, diffraction, signal reflection, bulk waves and temperature effects. Case histories are then presented detailing the application of these techniques to a television receiver, a cable television filter, and three 70 MHz radar filters of different bandwidths. It is concluded that problems remain in the analysis of second-order effects, the design of substrate materials, and the development of multilayer substrates.