Tunable surface acoustic wave resonators and filters

A frequency tunable SAW inter digital transducer IDT structure with embedded electrode doped regions for surface acoustic wave devices comprising

• a support substrate with a support substrate thickness;
• a first piezoelectric layer with a first piezoelectric layer thickness on said support substrate;
• a plurality of positive electrode doped regions embedded in said first piezoelectric layer, said positive electrode doped regions are piezoelectric semiconductors having a first doping type;
• a plurality of negative electrode doped regions embedded in said first piezoelectric layer, said negative electrode doped regions are piezoelectric semiconductors having a second doping type, wherein each said negative electrode doped region is between two adjacent positive electrode doped regions with a center to center distance between a positive electrode doped region and an adjacent negative electrode doped region controlled to a pitch b;
• a plurality of metallic positive electrode fingers each on one embedded positive electrode doped regions, said positive electrode fingers are connected to a positive electrode pad;
• a plurality of metallic negative electrode fingers each on one embedded negative electrode doped regions, said negative electrode fingers are connected to a negative electrode pad;
• and
• a DC biasing voltage is connected to said IDT through thin film bias resistors to control and vary dimensions of depletion regions formed in said embedded positive electrode doped regions and embedded negative electrode doped regions so that a loading mass and a metallization ratio associated with each said positive electrode fingers and each said negative electrode fingers are adjusted to achieve frequency tuning for surface acoustic waves to be excited or to be received in said IDT,
• said thin film bias resistors are integrated with said SAW IDT and resistance value of said thin film bias resistors is controlled to be sufficiently large to isolate RF signals from DC biasing circuit, whereas said positive electrode pad and negative electrode pad are connected to an electrical signal source or to a signal receiver to excite surface acoustic waves in said IDT or to receive surface acoustic waves from said IDT.