Patent ID: 7755455

Claim:
An apparatus, comprising: an insulating piezoelectric layer; a base electrode along a first side of the insulating piezoelectric layer; and at least one gradient electrode along a second side of the insulating piezoelectric layer, wherein the at least one gradient electrode is configured to provide a voltage gradient across an aperture of a surface acoustic wave (SAW) filter; wherein the base electrode and the at least one gradient electrode are configured to provide a voltage bias across the insulating piezoelectric layer, wherein the voltage bias comprises a gradient based on the voltage gradient across the aperture of the SAW filter; wherein the base electrode and the at least one gradient electrode are configured to control at least one frequency characteristic of the SAW filter based on the voltage bias across the insulating piezoelectric layer; wherein the at least one frequency characteristic comprises one or more of a center frequency of the SAW filter and a fractional bandwidth of the SAW filter; wherein the insulating piezoelectric layer is formed on a semiconductor substrate that comprises the base electrode; wherein the semiconductor substrate comprises a doped region that forms the base electrode.