Gallium phosphate plane resonators and filters

Gallium phosphate is a quartz analogue that possess much more intense piezoelectric properties. Here, we report a study made to determine more accurately the properties of filters that can be made using gallium phosphate AT cu resonators. The energy trapping properties of such resonators are first studied using computations and experiments; important differences with quartz are found. The computed and experimental vibrations modes are compared using synchrotron radiation X-ray topography determination. Using these results, we examine in detail the possibilities to build filters or diplexers with large bandwidth. Several topologies are considered (Jaumann filters including or not inductances, ladder filters, ...) and an experimental example is given. The obtained results demonstrate the large potential of this material for filtering applications.