US Patent 8009407 Adjustable capacitor and circuit provided therewith

A capacitor includes a multi layer structure on a ceramic or crystalline substrate. The multilayer structure includes a lower electrode, an upper electrode, and a dielectric that is tunable by a voltage applied to the electrodes. The multilayer structure is configured such that resonant oscillation modes of bulk acoustic waves can be propagated in the multilayer structure and such that the resonant frequencies of the oscillation modes are outside a first band range of between 810 and 1000 MHz, second band range of between 1700 and 2205 MHz and third band range of between 2400 and 2483.5 MHz.