Microacoustic Filter with an Acoustically-Decoupled Electrode Structure

An apparatus comprising:

• a microacoustic filter configured to generate a filtered signal from a radio-frequency signal, the microacoustic filter comprising:
• a substrate;
• means for producing a formed acoustic wave associated with a laterally-excited plate mode;
• means for converting the radio-frequency signal to an acoustic wave and converting the formed acoustic wave into the filtered signal;
• and
• means for separating the means for producing from the means for converting by forming a cavity between the means for producing and the means for converting.

A method of manufacturing a microacoustic filter, the method comprising:

• providing a piezoelectric layer having a crystalline structure operative to laterally excite a plate mode;
• providing a substrate;
• providing an electrode structure between the piezoelectric layer and the substrate, the electrode structure having a surface that faces the piezoelectric layer;
• and
• providing at least one spacer extending from the substrate past a plane defined by the surface of the electrode structure and towards the piezoelectric layer to form a cavity between the electrode structure and the piezoelectric layer.

A microacoustic filter comprising:

• a piezoelectric layer having a crystalline structure operative to laterally excite a plate mode;
• a substrate;
• and
• an electrode structure that is positioned between the piezoelectric layer and the substrate, the electrode structure having a surface that faces the piezoelectric layer and is separated by a gap from the piezoelectric layer.