RADIO FREQUENCY FILTER, RADIO FREQUENCY FRONT-END CIRCUIT, COMMUNICATION DEVICE, AND DESIGN METHOD FOR RADIO FREQUENCY FILTER
First Claim
1. A radio frequency filter comprising:
- a plurality of communication bandpass filters, each having a pass band corresponding to a different communication band;
a switch having a common terminal and a plurality of selectable terminals, the plurality of selectable terminals being respectively connected to one of the plurality of bandpass filters; and
a matching circuit having a first end connected to the common terminal,wherein the matching circuit is common to each of the plurality of communication bandpass filters, andeach of the plurality of communication bandpass filters are configured such that there is less signal transfer loss in the pass band when the bandpass filter is serially connected to the matching circuit than if no matching circuit were present.
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Accused Products
Abstract
A radio frequency filter includes communication bandpass filters disposed corresponding respectively to a plurality of communication bands, a switch, and a matching circuit. The switch includes a common terminal and a plurality of optionally selectable terminals, the plurality of optionally selectable terminals being individually connected to the plurality of bandpass filters in a one-to-one relation. The matching circuit is connected to the common terminal and is a common matching circuit to the plurality of communication bandpass filters. The plurality of communication bandpass filters are set such that filter characteristics of a serial circuit in combination of one of the plurality of communication bandpass filters, the one being selected by the switch, and the common matching circuit are improved in comparison with filter characteristics of the selected communication bandpass filter with respect to the communication band corresponding to the selected communication bandpass filter.
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Citations
17 Claims
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1. A radio frequency filter comprising:
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a plurality of communication bandpass filters, each having a pass band corresponding to a different communication band; a switch having a common terminal and a plurality of selectable terminals, the plurality of selectable terminals being respectively connected to one of the plurality of bandpass filters; and a matching circuit having a first end connected to the common terminal, wherein the matching circuit is common to each of the plurality of communication bandpass filters, and each of the plurality of communication bandpass filters are configured such that there is less signal transfer loss in the pass band when the bandpass filter is serially connected to the matching circuit than if no matching circuit were present. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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2. A radio frequency filter comprising:
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a switch having a common terminal and a plurality of selectable terminals; a matching circuit connected to the common terminal; and a plurality of communication bandpass filters, each connected to a respective one of the plurality of selectable terminals and having a pass band corresponding to different communication band, wherein each of the plurality of communication bandpass filters exhibits better filter characteristics when connected to the matching circuit by the switch, than the communication bandpass filter alone.
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17. A design method for a radio frequency filter comprising:
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a plurality of communication bandpass filters, each having a pass band corresponding to a different communication band; a switch having a common terminal and a plurality of selectable terminals, the plurality of selectable terminals being respectively connected to one of the plurality of communication bandpass filters; and a matching circuit having a first end connected to the common terminal and being common to each of the plurality of communication bandpass filters, the design method comprising steps of; obtaining an impedance of the matching circuit in each of the plurality of communication bands; and forming each of the plurality of communication bandpass filters with electrical components such that there is less signal transfer loss in the pass band when the bandpass filter is serially connected to the matching circuit than if no matching circuit were present.
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Specification