Specifying the Proper SAW Filter

Although SAW devices can greatly simplify RF filter designs, their successful use does require that they be properly specified. In addition to providing the center frequency and bandwidth for the filter, designers should consider a number of other factors that may affect system operation. These include the SAW filter’s insertion loss, signal group delay, out-of-band rejection ratio and thermal stability as well specifying the allowable ripple in the amplitude, phase and group delay responses. These factors affect the filter’s in-system operation as well as cost, and interactions among some of the factors may require that designers make tradeoffs.