Patent ID: 7687971

Claim:
An apparatus, comprising: a piezoelectric layer; a first electrode along a first side of the piezoelectric layer; and a second electrode along a second side of the piezoelectric layer; wherein the piezoelectric layer is between the first electrode and the second electrode; wherein the first and second electrodes are adapted to receive a voltage bias to create an electric field in the piezoelectric layer between the first and second electrodes that controls an acoustic velocity of a surface acoustic wave; wherein the piezoelectric layer comprises a piezoelectric material that is substantially insulating; wherein the first and second electrodes comprise slightly conductive doped layers of the piezoelectric material; wherein a solid comprises the piezoelectric layer, the first electrode, and the second electrode; the apparatus further comprising an input transducer and an output transducer, wherein the surface acoustic wave travels along a surface of the solid from the input transducer to the output transducer; wherein the input and output transducers are located on the first electrode; wherein the first electrode is configured to receive the voltage bias to create the electric field in the piezoelectric layer; wherein the first electrode is configured to prevent a short circuit between adjacent fingers of the input and output transducers and to reduce damping of the surface wave through induced electrical currents.