Appeal No. 1998-1467
Application 08/598,137
filter for reducing the signal height of a spurious peak that causes the extra-passband suppressibility to
deteriorate and occurs especially at a frequency outside a passband (see specification, page 1).
Appellants recognized that modification of conventionally equal reflector and inter-electrode pitches in
accordance with given resonant frequencies provides higher extra-passband suppressibility by
minimizing the presence of unwanted spurious peaks (see specification, pages 2 and 4).
Representative claim 9 is reproduced below:
9. A resonator-type surface-acoustic wave (SAW) filter comprising:
a plurality of SAW reonators connected in series and parallel with each other, each SAW
resonator has a pair of terminals as well as reflectors having electrodes and an interdigital transducer
having interdigital electrodes, wherein:
in at least one of said SAW resonators connected in series with another of said SAW
resonators, a pitch between adjoining electrodes, which is referred to as an inter-electrode
pitch 8 , in said reflectors is different from a pitch between adjoining interdigital electrodes,
SREF
which is referred to as an inter-electrode pitch 8 in said interdigital transducers; and
SIDT
in each of said SAW resonators connected in parallel, a pitch between adjoining electrodes in
said reflectors is the same as a pitch between adjoining interdigital electrodes in said interdigital
transducers.
The following references are relied on by the examiner:
Hikita et al. (Hikita) 5,115,216 May 19, 1992
Takagi JP 2-270,416 Nov. 5, 1990
Japanese Kokai Patent Application
Hickernell et al. (Hickernell) EP 530,547 Mar. 10, 1993
European Patent Application
2
Page: Previous 1 2 3 4 5 6 7 Next
Last modified: November 3, 2007