SAW FILTER

Surface acoustic wave filters, commonly known as SAW filters, are used primarily as bandpass and bandstop filters. Applications are typically commercial, low power filtering. In additions to SAW filters single resonators, called SAW resonators are available. These resonators are mainly used for SAW oscillator construction. SAW filters have found wide spread use in high volume commercial applications because of their low cost versus performance versus size. Some common applications that have adopted SAW filters include GPS, PCS, PCN, CDMA, Wireless LAN, GMS, CATV, Bluetooth, and keyless entry.

A SAW filter is manufactured on a substrate of quartz or lithium niobate by applying thin layers of metal. What differentiates a SAW filter from a crystal or monolithic filter is the mode of resonance. While traditional crystal resonators undergo transverse modes of oscillation SAW filters create surface waves, or Raleigh waves. Each Raleigh wave is generated by a series of interdigital strips of gold that collectively form an IDT. The wave is launched across the substrate to another IDT that converts the mechanical energy back to electrical. It is the spacing and length of each metal strip on the IDT that determines the passband and center frequency of the resulting filter. While these filters have great commercial appeal custom SAW filters require tooling. Thus for custom SAW filters there is typically a one time engineering charge.

Filtronetics, Inc. offers saw filters in either surface mount (SMD) or through-hole packages. Available frequency ranges from 20 MHz to over 2.5 GHz. Bandwidths can vary from 100 KHz to about 20 percent of the center frequency. We can provide from 1 piece to over 1 million SAW filters.