A review of thin-film resonator technology

Thin-film resonator technology has been under development for over 40 years as a means to reach higher frequencies than obtainable with conventional quartz-crystal technology. Using advances in microelectronic processing, thin films of piezoelectric materials are used to fabricate resonators and filters over a range of 500 MHz to 20 GHz. This article is a review of the thin-film resonator (TFR) technology that describes the core structures and issues and gives examples of filters and resonators that have been manufactured or demonstrated.