Acoustic surface wave resonator with suppressed direct coupled response

An acoustic surface wave resonator device comprising:

• substrate means having at least a surface of piezoelectric material on which acoustic surface waves may be propagated,
• first and second means on said substrate means for reflecting acoustic surface waves propagating thereon, said second reflecting means being disposed a predetermined distance from said first reflecting means so as to define a cavity therebetween for supporting a standing wave at a resonant frequency,
• input and output interdigital transducer means for electric to acoustic conversion at the input transducer means and acoustic to electric conversion at the output transducer means, said input and output transducer means being disposed on said substrate means in the cavity between said first and second reflecting means,
• each of said input and output transducer means including respective sets of opposed conductive transducer pads, and a plurality of interdigitated electrode finger means alternately originating from one and the other of the set of conductive transducer pads, and
• each of said pluralities of interdigitated electrode finger means of said input and output transducer means including intermediate portions thereof located in offset relationship to the peak of the standing wave to be established between said first and second reflecting means, each of said electrode finger means extending from the transducer pad corresponding thereto at a position centered upon the peak of the standing wave, said intermediate portion thereof being offset one-quarter wavelength between the linear portions of the electrode finger means.

An acoustic surface wave resonator device comprising:

• substrate means having at least a surface of piezoelectric material on which acoustic surface waves may be propagated,
• first and second means on said substrate means for reflecting acoustic surface waves propagating thereon, said second reflecting means being disposed a predetermined distance from said first reflecting means so as to define a cavity therebetween for supporting a standing wave at a resonant frequency,
• input and output interdigital transducer means for electric to acoustic conversion at the input transducer means and acoustic to electric conversion at the output transducer means, said input and output transducer means being disposed on said substrate means in the cavity between said first and second reflecting means,
• each of said input and output transducer means including respective sets of opposed conductive transducer pads, and a plurality of interdigitated electrode finger means alternately originating from one and the other of the set of conductive transducer pads, and
• each of said pluralities of interdigitated electrode finger means of said input and output transducer means including intermediate portions thereof located in offset relationship to the peak of the standing wave to be established between said first and second reflecting means, each of said electrode finger means extending from the transducer pads corresponding thereto at a position centered upon the peak of the standing wave, said intermediate portion thereof being declensionally offset one-quarter wavelength between the linear portions of the electrode finger means.

An acoustic surface wave resonator device comprising:

• substrate means having at least a surface of piezoelectric material on which acoustic surface waves may be propagated,
• first and second means on said substrate means for reflecting acoustic surface waves propagating thereon, said second reflecting means being disposed a predetermined distance from said first reflecting means so as to define a cavity therebetween for supporting a standing wave at a resonant frequency,
• input and output interdigital transducer means for electric to acoustic conversion at the input transducer means and acoustic to electric conversion at the output transducer means, said input and output transducer means being disposed on said substrate means in the cavity between said first and second reflecting means,
• each of said input and output transducer means including respective sets of opposed conductive transducer pads, and a plurality of interdigitated finger means alternately originating from one and the other of the set of conductive transducer pads, and
• each of said plurality of interdigitated electrode finger means of said input and output transducer means including intermediate portions thereof located in offset relationship to the peak of the standing wave to be established between said first and second reflecting means, each of said electrode finger means extending from the transducer pads corresponding thereto at a position centered upon the peak of the standing wave, each electrode finger means including a series of declensional offsets of one-quarter wavelength separated by linear portions of the electrode finger means, and the offsets in each series thereof being in alternating directions.

An acoustic surface wave resonator device comprising:

• substrate means having at least a surface of piezoelectric material on which acoustic surface waves may be propagated,
• first and second means on said substrate means for reflecting acoustic surface waves propagating thereon, said second reflecting means being disposed a predetermined distance from said first reflecting means so as to define a cavity therebetween for supporting a standing wave at a resonant frequency,
• input and output interdigital transducer means for electric to acoustic conversion at the input transducer means and acoustic to electric conversion at the output transducer means, said input and output transducer means being disposed on said substrate means in the cavity between said first and second reflecting means,
• each of said input and output transducer means including respective sets of opposed conductive transducer pads, and a plurality of interdigitated electrode finger means alternately originating from one and the other of the set of conductive transducer pads, and
• each of said pluralities of interdigitated electrode finger means of said input and output transducer means including intermediate portions thereof located in offset relationship to the peak of the standing wave to be established between said first and second reflecting means, each of said electrode finger means comprising pairs of fingers in the split electrode configuration for interdigital transducers such that the finger pairs are centered upon the peak of the standing wave, each of said finger pairs including one linear finger perpendicularly extended from the transducer pad corresponding thereto, and a finger having an intermediate angular offset portion laterally crossing over the linear finger.

An acoustic surface wave resonator comprising:

• substrate means having at least a surface layer of piezoelectric material on which acoustic surface waves may be propagated,
• first and second means on said substrate means for reflecting acoustic surface waves propagating thereon, said second reflecting means being disposed a predetermined distance from said first reflecting means so as to define a cavity therebetween for supporting a standing wave at a resonant frequency,
• input and output interdigital transducer means for electric to acoustic conversion at the input transducer means and acoustic to electric conversion at the output transducer means, said input and output transducer means being disposed on said substrate means in the cavity between said first and second reflecting means,
• each of said input and output transducer means including respective sets of opposed conductive transducer pads, and a plurality of interdigitated electrode finger means alternately originating from one and the other of the set of conductive transducer pads,
• and each of said pluralities of interdigitated electrode finger means of said input and output transducer means linearly extending from the transducer pads corresponding thereto at a slope designated by the formula .lambda./2d, where .lambda. is the wavelength at the resonant frequency and d is the length of the electrode.