Weighted SAW reflector using distributed acoustic reflective dots

A reflector for reflecting surface acoustic waves, said reflector comprising:

• a piezoelectric substrate;
• a grating structure disposed on the substrate, said grating structure including spaced apart grid lines, said grid lines defining gaps therebetween, said gaps being either uniformly or non-uniformly spaced;
• and
• a plurality of acoustic reflective dots distributed within the gaps and/or on the grid lines, said reflective dots having a predetermined density and sequence that determines the net reflectivity of the grating structure and controls the magnitude and phase of the reflected surface acoustic waves, wherein the dot distribution has a predetermined sampling period, said sampling period being defined by M grid lines per each N wavelength (Nλ/M) of the surface acoustic waves, where λ is the wavelength of the center frequency of a frequency band of interest, M and N are integers and M>N.

A SAW filter for filtering a signal, said filter comprising:

• a piezoelectric substrate;
• at least one input transducer disposed on the substrate, said input transducer being responsive to the input signal and generating surface acoustic waves propagating on the piezoelectric substrate in response to the signal;
• at least one reflective grating disposed on the substrate for reflecting the acoustic waves from the at least one input transducer, said grating including spaced apart grid lines defining gaps therebetween, said grating further including distributed acoustic reflective dots disposed relative to the grid lines in a predetermined manner, wherein a density and sequence of the distributed acoustic reflective dots controls the magnitude and phase of the reflected acoustic waves;
• and
• at least one output transducer disposed on the substrate, said output transducer being responsive to the reflected acoustic waves from the reflective grating, said at least one output transducer converting the acoustic waves into electrical energy.