Piezoelectric resonance wave filter and duplexer

A piezoelectric resonator, piezoelectric resonance technology, applied in the direction of electrical components, impedance networks, etc., can solve the problem that the thickness of the film cannot be optimized

Active Publication Date: 2004-06-23
快速追踪有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For this reason, even in the case of using silicon oxide as the material of the thin film, the thickness of the thin film cannot be optimized so that the temperature coefficient of the resonant frequency of the resonator approaches zero

Method used

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  • Piezoelectric resonance wave filter and duplexer
  • Piezoelectric resonance wave filter and duplexer
  • Piezoelectric resonance wave filter and duplexer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0071] Embodiments of the present invention are described in more detail below with reference to the accompanying drawings. refer to Figure 4 , the configuration of the duplexer according to the embodiment of the present invention will be described first. Figure 4 is a circuit diagram of a duplexer according to this embodiment. The duplexer 90 according to this embodiment has antenna terminals 91 and 92, which are connected to an antenna not shown; transmission signal terminals 93 and 94, which are connected to a transmission circuit not shown, for outputting a transmission signal to the antenna; And reception signal terminals 95 and 96 are connected to an unillustrated reception circuit for inputting a reception signal from the antenna.

[0072] The duplexer 90 also has a transmission filter 97 for passing a transmission signal but cutting a reception signal; and a reception filter 98 for passing a reception signal but cutting a transmission signal. Each filter 97 and 98 h...

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Abstract

A piezoelectric resonant filter includes a group of series resonators and a group of parallel resonators for forming a ladder-type filter circuit. Each of the resonators has a piezoelectric thin film 15 having piezoelectric characteristic, and lower and upper electrodes 14 and 16 disposed on opposite surfaces of the piezoelectric thin film 15 for applying an excitation voltage to the piezoelectric thin film 15. The group of the parallel resonators exhibits a low frequency side attenuation extremum in the filter whereas the group of the series resonators exhibits a high frequency side attenuation extremum in the filter. At least one of the group of the series resonators and the group of the parallel resonators has a temperature compensating layer 20 for bringing the temperature coefficient of the resonant frequency close to zero. The thickness of the temperature compensating layer 20 in the group of the series resonators is different from the thickness of the temperature compensating layer 20 in the group of the parallel resonators.

Description

technical field [0001] The present invention relates to a piezoelectric resonant filter including a thin-film piezoelectric resonator, and a duplexer including such a piezoelectric resonant filter. Background technique [0002] In mobile communication devices such as cellular phones which have been remarkably spread in recent years, reduction in size and increase in operating frequency have been improved year by year. For this reason, electronic components used in mobile communication devices also need to be reduced in size and increase in operable frequency. [0003] Some mobile communication devices have duplexers for switching between transmit and receive signal paths so that one antenna can be used for both transmission and reception. The duplexer has a transmission filter for passing the transmission signal but cutting off the reception signal, and a reception filter for passing the reception signal but cutting off the transmission signal. [0...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/58H03H3/04H03H9/02H03H9/17H03H9/24H03H9/60H03H9/70
CPCH03H9/02102H03H9/605H03H3/04H03H9/706H03H2003/0407H03H9/02149H03H9/175H03H9/174H03H9/24
Inventor 小室荣树斋藤久俊野口隆男阿部秀典
Owner 快速追踪有限公司
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