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US 5,296,824 AGranted
Low loss wide bandwidth parallel channel acoustic filter
AssigneeMotorola, Inc.
InventorsFrederick Y. Cho, Thomas S. Hickernell, David Penunuri
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Abstract
An acoustic wave filtering apparatus includes an acoustic wave propagating substrate for supporting propagation of acoustic waves and a plurality of acoustic wave filters for filtering an electrical signal. Each of said plurality further comprises an input for supplying electrical input signals, an input unidirectional acoustic wave transducer for converting electrical signal energy into acoustic energy, an output unidirectional acoustic wave transducer for converting acoustic signals to electrical signals, and an output for combining and delivering electrical output signals to external electrical apparatus.
Claims27
A method for providing wide bandwidth, low band-pass insertion loss acoustic filters comprising the steps of:
- providing an acoustic wave propagating substrate;
- coupling a first acoustic wave filter having a first input, a first output, a first center frequency, low insertion loss and a first bandwidth to the acoustic wave propagating substrate;
- coupling a second acoustic wave filter having a second input, a second output, a second centre frequency, low insertion loss and a second bandwidth to the acoustic wave propagating substrate, said first and second acoustic wave filters each including corresponding electrodes having a common width and a common periodicity;
- connecting the first and second inputs directly together to provide a common input;
- supplying an input signal to the common input;
- providing by the first output, a first output signal;
- providing by the second output, a second output signal;
- connecting the first and second outputs directly together to provide a common output;
- and
- combining the first and second output signals by the common output to produce an output signal having a wide bandwidth, wherein said wide bandwidth is greater than either the first or second bandwidth.
7 more elements
A wide bandwidth acoustic wave filter comprising:
- a piezoelectric substrate comprising a piezoelectric material including a surface;
- a first acoustic wave filter, having a first center frequency, low loss and a first bandwidth, disposed on said surface of said piezoelectric substrate;
- a second acoustic wave filter, having a second center frequency, low loss and a second bandwidth, disposed on said surface of said piezoelectric substrate, said first and second acoustic wave filters including corresponding electrodes having a common width and a common periodicity;
- an input commonly connected to said first and second acoustic wave filters, said input receiving a first input signal and coupling said first input signal to said first and second acoustic wave filters;
- said first acoustic wave filter providing a first output signal in response to said first input signal;
- said second acoustic wave filter providing a second output signal in response to said first input signal;
- and
- an output commonly connected to said first and second acoustic wave filters, said output combining said first and second output signals from said first and second acoustic wave filters to provide a width bandwidth, low loss acoustic wave filter output, wherein said wide bandwidth is greater than either said first or said second bandwidth.
5 more elements
A wide bandwidth acoustic wave filtering apparatus including in combination:
- acoustic wave propagating substrate means for supporting propagation of acoustic waves;
- a plurality of acoustic wave filtering means for filtering an electrical input signal;
- an input commonly connected to each of said plurality of acoustic wave filtering means, said input receiving said electrical input signal and coupling said electrical input signal to each of said plurality of acoustic wave filtering means;
- each of said plurality of acoustic wave filtering means having a distinct center frequency and a distinct bandwidth, each of said plurality of acoustic wave filtering means including corresponding electrodes having a common width and a common periodicity, each of said plurality of acoustic wave filtering means comprising:
- input means for receiving said electrical input signal, said input means coupled to said input;
- input unidirectional acoustic wave transducer means for converting said electrical input signal into acoustic energy, said input unidirectional acoustic wave transducer means coupled to said input means;
- and
- output unidirectional acoustic wave transducer means for converting said acoustic energy to an output electrical signal, said output unidirectional acoustic wave transducer means acoustically coupled to said input unidirectional acoustic wave transducer means, wherein said input and output unidirectional acoustic wave transducer means comprise said corresponding electrodes having said common width and said common periodicity;
- and
- said wide band acoustic wave filter apparatus further including output means, said output means commonly connected to each of said output unidirectional acoustic wave transducer means, said output means for combining said electrical output signals from each of said plurality of acoustic wave filtering means and delivering a filtered electrical output signal having a broad bandwidth and low acoustic loss, wherein said broad bandwidth exceeds each of said distinct bandwidths.
7 more elements
In a radio frequency apparatus, at least one surface acoustic wave (SAW) filter for providing a frequency selection function, said SAW filter comprising:
- acoustic wave propagating substrate means for supporting propagation of acoustic waves;
- an input receiving an electrical input signal;
- a plurality of acoustic wave filtering means each coupled to said input, each of said plurality of acoustic wave filtering means for filtering said electrical input signal, each of said plurality of acoustic wave filtering means having a distinct center frequency and a distinct bandwidth, each of said plurality of acoustic wave filtering means including corresponding electrodes of a common width and a common periodicity, each of said plurality of acoustic wave filtering means further comprising:
- input means coupled to said input for receiving said electrical input signal;
- input unidirectional acoustic wave transducer means for converting said electrical input signal coupled by said input means into acoustic energy, said input unidirectional acoustic wave transducer means coupled to said input means;
- and
- output unidirectional acoustic wave transducer means for converting said acoustic energy to an output electrical signal, said output unidirectional acoustic wave transducer means acoustically coupled to said input unidirectional acoustic wave transducer means, wherein said input and output unidirectional acoustic wave transducer means comprise said corresponding electrodes having said common width and said common periodicity;
- and
- said wide band acoustic wave filter apparatus further including output means, said output means commonly connected to said output unidirectional acoustic wave transducer means, said output means combining said electrical output signals from each of said plurality of acoustic waves filtering means and delivering a filtered electrical output signal having a broad bandwidth and low acoustic loss, wherein said broad bandwidth is greater than each of said distinct bandwidths.
6 more elements
In a radio frequency apparatus, at least one surface acoustic wave (SAW) filter for providing a frequency selection function, said SAW filter comprising:
- a piezoelectric substrate comprising a piezoelectric material including a surface;
- a first acoustic wave filter, having a first center frequency, low loss and a first bandwidth, disposed on said surface of said piezoelectric substrate;
- a second acoustic wave filter, having a second center frequency, low loss and a second bandwidth, disposed on said surface of said piezoelectric substrate, said first and second acoustic wave filters comprising corresponding electrodes having a common width and a common periodicity;
- an input directly connected to said first and second acoustic wave filters, said input receiving a first input signal and coupling said first input signal to said first and second acoustic wave filters;
- said first acoustic wave filter providing a first output signal in response to said first input signal;
- said second acoustic wave filter providing a second output signal in response to said first input signal;
- and
- an output directly connected to said first and second acoustic wave filters, said output combining said first and second output signals from said first and second acoustic wave filters and delivering a wide bandwidth, low-loss acoustic wave filter output, wherein said wide bandwidth exceeds either said first or said second bandwidth.
5 more elements
An acoustic filter having an input receiving electrical signals and an output providing electrical signals, said acoustic filter comprising:
- a first acoustic wave filter having a first center frequency, comprising a first transducer connected directly to said input and a second transducer connected directly to said output, said first transducer acoustically coupled to said second transducer, said first and second transducers each comprising a first acoustic reflector, a first gap having a first width and a first acoustic transducer, said first gap separating said first acoustic reflector from said first acoustic transducer;
- and
- a second acoustic wave filter having second center frequency, comprising a third transducer connected directly to said input and a fourth transducer connected directly to said output, said third transducer acoustically coupled to said fourth transducer, said third and fourth transducers each comprising a second acoustic reflector, a second gap having a second width and a second acoustic transducer, said second gap separating said second acoustic reflector from said second acoustic transducer, wherein said first and second gap widths differ by one-fourth of an acoustic wavelength of said first center frequency.
Dependencies are inferred from the claim text.