Efficient surface acoustic wave device capable of excitation in plural frequency bands, and signal receiver and communication system utilizing the same

A surface acoustic wave device comprising:

• a piezoelectric substrate;
• plural interdigital transducers provided on said piezoelectric substrate, for exciting surface acoustic waves, each of said interdigital transducers being provided with plural portions of mutually different pitches of electrode fingers, respectively corresponding to different frequencies, and said portions being arranged in parallel manner in a direction perpendicular to the propagating direction of the surface acoustic waves;
• and
• a wave guide path provided on said piezoelectric substrate, for outputting a convolution signal by the surface acoustic waves excited by said plural interdigital transducers;
• wherein the surface acoustic waves generated by said interdigital transducers are entered in concentrated manner into said wave guide path.

A signal receiver comprising:

• a code generator for generating a reference signal;
• a surface acoustic wave device for outputting a convolution signal of a received signal and the reference signal;
• and
• a circuit for demodulating information, using the convolution signal outputted from the surface acoustic wave device;
• wherein said surface acoustic wave device includes:
• a piezoelectric substrate;
• plural interdigital transducers provided on said piezoelectric substrate, for exciting surface acoustic waves, each of said interdigital transducers being provided with plural portions of mutually different pitches of electrode fingers, respectively corresponding to different frequencies, and said portions being arranged in parallel manner in a direction perpendicular to the propagating direction of the surface acoustic waves;
• and
• a wave guide path provided on said piezoelectric substrate, for outputting a convolution signal by the surface acoustic waves excited by said plural interdigital transducers;
• wherein the surface acoustic waves generated by said interdigital transducers are entered in concentrated manner into said wave guide path.

A communication system comprising:

• a transmitter for transmitting a signal modulated according to information;
• and
• a receiver including:
• a code generator for generating a reference signal;
• a surface acoustic wave device for outputting a convolution signal of a received signal and the reference signal;
• and
• a circuit for demodulating information, using the convolution signal outputted from said surface acoustic wave device, said surface acoustic wave device including:
• a piezoelectric substrate;
• plural interdigital transducers provided on said piezoelectric substrate, for exciting surface acoustic waves;
• each of said interdigital transducers being provided with plural portions of mutually different pitches of the electrode fingers, respectively corresponding to different frequencies, and said portions being arranged in parallel manner in a direction perpendicular to the propagating direction of the surface acoustic waves;
• and
• a wave guide path provided on said piezoelectric substrate, for outputting a convolution signal by the surface acoustic wave excited by said plural interdigital transducers;
• wherein the surface acoustic waves generated by said interdigital transducers in said surface acoustic wave device are entered in concentrated manner into said wave guide path.