In an array of acoustic resonators, the effective coupling coefficient of first and second filters are individually tailored in order to achieve desired frequency responses. In a duplexer embodiment, the effective coupling coefficient of a transmit band-pass filter is lower than the effective coupling coefficient of a receive band-pass filter of the same duplexer. In one embodiment, the tailoring of the coefficients is achieved by varying the ratio of the thickness of a piezoelectric layer to the total thickness of electrode layers. For example, the total thickness of the electrode layers of the transmit filter may be in the range of 1.2 to 2.8 times the total thickness of the electrode layers of the receive filter. In another embodiment, the coefficient tailoring is achieved by forming a capacitor in parallel with an acoustic resonator within the filter for which the effective coupling coefficient is to be degraded. Preferably, the capacitor is formed of the same materials used to fabricate a film bulk acoustic resonator (FBAR). The capacitor may be mass loaded to change its frequency by depositing a metal layer on the capacitor. Alternatively, the mass loading may be provided by forming the capacitor directly on a substrate.

Controlled effective coupling coefficients for film bulk acoustic resonators

A microwave filter made of acoustically coupled, bulk wave acoustic resonators. The resonators utilize piezoelectric materials sandwiched between conducting electrodes. Layers of material that intervene between the resonators control the amount of acoustic coupling between the resonators and the amount of coupling is selected to obtain desired filter characteristics. The resonators and the intervening layers may be supported upon a substrate by means of a series of layers of material that function as an acoustic mirror or reflector.

Coupled resonator bulk acoustic wave filter

A piezoelectric thin film resonator includes: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode located to sandwich the piezoelectric film; a load film formed from patterns in a resonance region in which the lower electrode and the upper electrode face each other across the piezoelectric film, wherein the patterns are formed so as to surround a center of the resonance region and intersect with a pathway extending from the center to an outer periphery of the resonance region.

Piezoelectric thin-film resonator and filter

A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed An FBAR is fabricated on a substrate by introducing a mass loading electrode to a bottom electrode layer For a substrate having multiple resonators, mass loading bottom electrode is introduced for only selected resonator to provide resonators having different resonance frequencies on the same substrate

Method of mass loading of thin film bulk acoustic resonators (fbar) for creating resonators of different frequencies and apparatus embodying the method

A piezoelectric resonator is disclosed. In one embodiment the piezoelectric resonator includes a resonating member having a bi-directionally adjustable resonance frequency, the resonating member including a semiconductor material of a semiconductor-on-insulator wafer, the semiconductor-on-insulator wafer including an oxide layer adjacent to the semiconductor material and a handle layer adjacent to the oxide layer, the oxide layer disposed between the handle layer and the semiconductor material, and electrode, and a piezoelectric material disposed between the semiconductor material and the electrode, and a capacitor created by the semiconductor material and the handle layer separated by an air gap formed out of the oxide layer, wherein the capacitor is configured to receive a direct current voltage that adjusts the resonance frequency of the resonating member.

Piezoelectric on semiconductor-on-insulator microelectromechanical resonators

An improved piezoelectric resonator having multiple layers of material within each electrode of the resonator. One layer of material within each electrode is selected and used to increase the effective coupling coefficient between the piezoelectric layer of material in the resonator and the electric fields resulting from the voltages applied to the electrodes. The second layer of material within each electrode is selected and used to decrease the electrical losses within the electrodes.

Kenneth Meade Lakin

Papers

Piezoelectric resonator with layered electrodes