| 摘要 |
PROBLEM TO BE SOLVED: To obtain a quadrature modulation circuit and a transmitter capable of canceling spurious components with a quadrature modulator by adding a simple circuit to the input side and in which increase of signal sources, increase of the number of components and increase of circuit scale are suppressed as much as possible. SOLUTION: The quadrature modulation circuit is provided with each high-pass type active filer for extracting only noise components from base band signals I, Q, respectively and for amplifying them to be doubled, each synthesizer for compositing the each noise component and differential base band signals I', Q' and for outputting synthetic differential base band signals I'<SB>1</SB>, Q'<SB>1</SB>, respectively and the quadrature modulator for canceling the noise components included in each channel from the respectively corresponding base band signals I, Q and synthetic base band signals I'<SB>1</SB>, Q'<SB>1</SB>and for outputting a modulation signal by local oscillation waves. COPYRIGHT: (C)2004,JPO&NCIPI
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