# US 5,708,403 A · Saw resonator having transverse mode ripple at antiresonance point

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- Number: US 5,708,403 A
- Document ID: US5708403A
- Status: Granted
- Kind: A
- Application number: 08/609,502
- Filed: 1996-03-01
- Granted: 1998-01-13
- Earliest claimed: 1995-03-03
- Assignees: Murata Manufacturing Co., Ltd.
- Inventors: Kazuhiko Morozumi; Michio Kadota
- Web page: https://patentgrep.com/patent/US5708403A

## CPC

- H04N 5/4446: {IF amplifier circuits specially adapted for B&W TV (RF amplifiers in general H03F3/189)}
- H03H 9/6496: {Reducing ripple in transfer characteristic}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

A SAW resonator for forming a frequency trap has a surface wave substrate and at least one interdigital transducer located on the surface wave substrate. The interdigital transducer includes a pair of comb-shaped electrodes each having a plurality of electrode fingers arranged so that the pair of comb-shaped electrodes interdigitates with each other. An overlapping width of the electrode fingers of the interdigital transducer is set such that in an impedance-frequency characteristic a transverse mode ripple occurring between a resonance point and an antiresonance point is located at the antiresonance point.

## Claims

### Claim 1

A SAW resonator comprising:
a surface wave substrate;
at least one interdigital transducer located on the surface wave substrate, the interdigital transducer including a pair of comb-shaped electrodes each having a plurality of electrode fingers arranged so that the pair of comb-shaped electrodes interdigitates with each other; wherein
an overlapping width of the electrode fingers of the interdigital transducer causes a transverse mode ripple, occurring between or adjacent to a resonance point and an antiresonance point, to be located substantially at the antiresonance point in such a manner that a peak point of the antiresonance point is dulled.

### Claim 2 (depends on 1)

A SAW resonator according to claim 1, wherein the overlapping width is in a range from about 2.8 .lambda. to 3.1 .lambda., where X is a wavelength of a surface acoustic wave excited on the surface wave substrate.

### Claim 3 (depends on 1)

A SAW resonator according to claim 1, wherein an impedance of the SAW resonator has a minimum value at the resonance point and a maximum value at the antiresonance point.

### Claim 4 (depends on 1)

A SAW resonator according to claim 1, wherein the resonance point is substantially equal to one of an adjacent channel picture signal frequency and an adjacent channel sound signal frequency of a television receiver.

### Claim 5 (depends on 1)

A saw resonator according to claim 1, wherein the overlapping width of each of the electrode fingers has substantially the same value which is in a range from about 2.8 .lambda. to 3.1 .lambda., where .lambda. is a wavelength of a surface acoustic wave excited on the surface wave substrate.