Surface acoustic wave device

A surface acoustic wave device, comprising:

• a substrate of piezoelectric material;
• said substrate being adapted to propagate an acoustic surface wave having a predetermined center frequency along a first predetermined path therein;
• a transmitting transducer disposed on said piezoelectric substrate at a first location for generating a first acoustic surface wave and causing it to propagate along said predetermined path in said piezoelectric substrate responsive to an input signal applied thereto;
• said transmitting transducer having a center as measured along said predetermined path;
• a receiving transducer disposed on said piezoelectric substrate at a second location on said predetermined path and having a plurality of sections, said sections of said receiving transducer being aligned with each other along said path, each consecutive two of said sections of said receiving transducer being spaced a first predetermined distance from each other as measured along said predetermined path, said receiving transducer having a center as measured along said predetermined path and said center of said receiving transducer being spaced from said center of said transmitting transducer by a second predetermined distance as measured along said predetermined path;
• said receiving transducer being adapted to convert said first acoustic surface wave to an electrical output signal and also to generate an undesired reflected wave;
• and
• a reflecting transducer disposed on said piezoelectric substrate at said second location on said predetermined path and having a plurality of sections, said sections of said reflecting transducer being interleaved with said sections of said receiving transducer in such a manner that said sections of said receiving and reflecting transducers are alternately aligned along said path;
• said reflecting transducer having a center as measured along said predetermined path and said center of said reflecting transducer being spaced from said center of said transmitting transducer by a third predetermined distance as measured along said predetermined path, said third distance being different from said second predetermined distance, said reflecting transducer being responsive to said first surface acoustic wave generated by the transmitting transducer to generate a cancellation reflected wave which propagates along said predetermined path substantially in counterphase with said undesired reflected wave, whereby said undesired reflected wave is cancelled by said cancellation reflected wave.

A surface acoustic wave device (SAW), comprising:

• a substrate of piezoelectric material;
• said substrate being adapted to propagate an acoustic surface wave having a predetermined center frequency along a first predetermined path therein;
• a transmitting transducer disposed on said piezoelectric substrate at a first location for generating a first acoustic surface wave and causing it to propagate along said predetermined path in said piezoelectric substrate responsive to an input signal applied thereto, said transmitting transducer having a plurality of sections which are aligned with each other along said path, each consecutive two of said sections of said transmitting transducer being spaced a first predetermined distance from each other;
• a receiving transducer disposed on said piezoelectric substrate at a second location on said predetermined path, said receiving transducer and said transmitting transducer each having a respective center as measured along said path, said center of said receiving transducer being spaced from said center of said transmitting transducer by a second predetermined distance;
• said receiving transducer being adapted to convert said first acoustic surface wave to an electrical output signal and also to generate an undesired reflected wave responsive to said first acoustic surface wave;
• and
• a reflecting transducer disposed on said piezoelectric substrate at said first location on said predetermined path and having a plurality of sections, said sections of said reflecting transducer being interleaved with said sections of the transmitting transducer in such a manner that said sections of said transmitting and reflecting transducers are alternately aligned along said path;
• said reflecting transducer having a center as measured along said predetermined path, and said center of said reflecting transducer being spaced from said center of said receiving transducer by a third predetermined distance which is different from said second predetermined distance;
• said reflecting transducer being adapted to generate, responsive to said first surface acoustic wave generated by said transmitting transducer, a cancellation reflected wave which propagates along said predetermined path substantially in counterphase with said undesired reflected wave, whereby said undesired reflected wave is cancelled by said cancellation reflected wave.