| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-cost filter circuit which is small and integrated, and by which disturbance signals of arbitrary frequencies can be eliminated. SOLUTION: The filter circuit is provided with a 90°phase shifter 5 to which desired signals and disturbance signals are inputted; a first phase shifter 1 which has phase shift amounts different between the desired signal frequency, and the disturbance signal frequency and to which one output a1 of the 90°phase shifter 5 is inputted; a second phase shifter 2 to which the other output b1 of the 90°phase shifter 5 is inputted; and a synthesizer 6 to which an output cl of the first phase shifter 1 and an output d1 of the second phase shifter are inputted, and which synthesizes the two outputs. The first phase shifter 1 and the second phase shifter 2 perform phase shifting processing by different phase shift amounts between the desired signal frequency and the disturbance signal frequency. The synthesizer 6, to which the output c1 of the first phase shifter 1 and the output d1 of the second phase shifter 2 are inputted and which synthesizes the outputs, offsets and eliminates the disturbance signals and allows only the desired signals to pass through. COPYRIGHT: (C)2007,JPO&INPIT
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