Filter device, and duplexer and multiplexer provided with filter device
A filter and resonator technology, applied in the direction of electrical components, impedance networks, etc., can solve the problems of reduced passband input loss, damaged attenuation band attenuation characteristics, large passband input loss, etc., to achieve the effect of reducing input loss
Pending Publication Date: 2021-04-16
MURATA MFG CO LTD
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Problems solved by technology
However, for example, if an inductor is connected in series to the parallel arm resonator, the antiresonance frequency of the parallel arm resonator remains almost the same and the resonance frequency shifts to the lower frequency side, so the input loss in the pass band decreases, but the attenuation characteristics of the attenuation band The steepness of
On the other hand, for example, if many parallel arm resonators are added to the ladder filter circuit, the steepness of the attenuation characteristic in the attenuation band will increase, but the input loss in the pass band will increase.
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[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code|symbol is attached|subjected to the same element, and overlapping description is abbreviate|omitted.
[0027] figure 1 It is a diagram showing an example of the circuit configuration of the filter device 10 according to the first embodiment. An antenna for transmitting and receiving radio frequency (RF: Radio Frequency, radio frequency) signals is sometimes used in a mobile communication device. In such a case, for example, a wave splitter is used to separate the transmitted signal from the received signal. The filter device 10 can constitute, for example, a transmission signal filter circuit and a reception signal filter circuit for constituting such a demultiplexer. The demultiplexer may be, for example, a composite filter device that includes a plurality of filter circuits and divides signals of a plurality of frequency bands. Th...
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The invention provides a filter device, a duplexer and a multiplexer. The filter device includes a plurality of series arm resonators and a plurality of parallel arm resonators provided in a filter chip, and a plurality of inductors connected in series with each of a part of the parallel arm resonators included in the plurality of parallel arm resonators. A first inductor having the largest inductance among the plurality of inductors is connected in series to a first parallel arm resonator having the largest anti-resonance frequency among the plurality of parallel arm resonators. One end of the first parallel arm resonator and one end of a second parallel arm resonator included in another part of the plurality of parallel arm resonators are connected to the same wiring among a plurality of wirings separated by the plurality of series arm resonators on a line connecting an input terminal and an output terminal of the filter chip. The other end of the first parallel arm resonator is connected to a first ground terminal of the filter chip, and the other end of the second parallel arm resonator is connected to a second ground terminal of the filter chip.
Description
technical field [0001] The invention relates to filter arrangements. Background technique [0002] In a mobile communication device such as a mobile phone, a common antenna may be used for transmitting a transmission signal and receiving a reception signal in order to reduce the size of the terminal. A duplexer that separates the transmitted and received signals is connected to such an antenna. As an example of a duplexer, a ladder-type filter circuit that passes a signal of a given frequency band by connecting a plurality of resonators having a natural resonance frequency and an anti-resonance frequency in a ladder type can be used. , and attenuate signals in other frequency bands. [0003] For example, Patent Document 1 describes a ladder-type filter including a series arm resonator, a parallel arm resonator, and an inductor connected in series to the parallel arm resonator. [0004] prior art literature [0005] patent documents [0006] Patent Document 1: Internatio...
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Login to View More IPC IPC(8): H03H9/48H03H9/54H03H9/64H03H9/70H03H9/72
CPCH03H9/6483H03H2001/0078H03H9/568H03H9/542H03H9/02559H03H9/0557H03H9/725H03H9/52H03H9/13H03H9/70H03H9/205
Inventor 近藤清磨
Owner MURATA MFG CO LTD