Surface acoustic wave filter device formed on a plurality of piezoelectric substrates

A communication apparatus comprising:

• an antenna for receiving or transmitting a signal;
• a first surface acoustic wave sub-filter having a first filter characteristic and electrically connected to the antenna;
• and
• a second surface acoustic wave sub-filter having a second filter characteristic and electrically connected to said first surface acoustic wave sub-filter;
• wherein said first and second surface acoustic wave sub-filters are provided on a first and second piezoelectric substrates having mutually distinctive electro-mechanical coupling coefficients, respectively, and said first and second filter characteristics are such characteristics that synthesis of said first and second filter characteristics form a combined filter having a desired filter characteristic.

A surface acoustic wave device comprising:

• a plurality of surface acoustic wave elements including a plurality of piezoelectric substrates;
• and
• connecting means for electrically connecting said surface acoustic wave elements so that said surface acoustic wave elements are combined with each other to form a combined and desired characteristic,
• wherein said piezoelectric substrates have different electro-mechanical coupling coefficients.

A surface acoustic wave device comprising:

• a first surface acoustic wave element having a first characteristic desired to transmit a signal;
• a second surface acoustic wave element having a second characteristic different from said first characteristic, said first and second surface acoustic wave elements being provided on a first piezoelectric substrate, said second characteristic being such that a third characteristic desired to receive a signal is formed when said second characteristic is combined with a fourth characteristic of a third surface acoustic wave element provided on a second piezoelectric substrate having an electro-mechanical coupling coefficient different from that of said first piezoelectric substrate;
• and
• a package means for packaging both of said first and second surface acoustic wave elements.

A wave filter comprising:

• transceiver means for communicating an external radio frequency signal;
• means for receiving a received radio frequency signal from the transceiver means;
• a first piezoelectric substrate, having a first electro-mechanical coupling coefficient, including,
• a first surface acoustic wave generator means having a first electrode and a first common electrode,
• a second surface acoustic wave generator means having a second electrode and sharing the first common electrode with the first surface acoustic wave generator means;
• first coupling means for inducing a signal into the first electrode in accordance with the received radio frequency signal, and
• means for outputting, from the first common electrode, an intermediate signal induced therein from the received radio frequency;
• a second piezoelectric substrate, having a second electro-mechanical coupling coefficient distinct from the first electro-mechanical coupling coefficient, including,
• a third surface acoustic wave generator means having a third electrode and a second common electrode,
• a fourth surface acoustic wave generator means having a fourth electrode and sharing the second common electrode with the third surface acoustic wave generator means;
• second coupling means for inducing a signal into the third electrode in accordance with the intermediate signal, and
• means for outputting, from the third electrode, an output signal induced therein from the intermediate signal.