Generally, high frequency dielectric materials for filters and resonators require a relatively high dielectric constant (E.sub.r), a high unloaded dielectric Q, and a low absolute value of a resonant frequency temperature coefficient (T.sub.f). Currently, most widely used, commercially available dielectric materials such as Ba.sub.2 Ti.sub.9 O.sub.20 and BaNd.sub.2 Ti.sub.5 O.sub.14 exhibit E.sub.r values of approximately 37 and 78, respectively, Q values of 15000 and 8000, respectively, and T.sub.f values of 8 ppm/.degree. C. and 40 ppm/.degree. C., respectively. A need exists for smaller filters and resonators, thereby requiring dielectric materials with a higher E.sub.r that simultaneously maintains a relatively low T.sub.f.
USPTO Backgrounds
USPTO Backgrounds