| 摘要 |
PROBLEM TO BE SOLVED: To provide a sigma delta modulator capable of setting a center frequency at which quantization noise power is minimum and a tone generated by mismatching is avoided. SOLUTION: The sigma delta modulator receives an analog signal X. A modulation unit 310 of the modulator includes two signal converters 318, 320, which respectively have analog signal sections 328, 368, and digital signal sections 338, 378. The signal converters 318, 320 respectively receive analog signals X<SB>1</SB>, Y<SB>2</SB>having a phase offset of a first phase difference. Two feedback sections are respectively coupled between an output position of the one signal converter and the analog signal section of the other signal converter to transmit a feedback signal with a phase offset of a second phase difference. A digital output signal Y is a sum of output signals of the two signal converters 318, 320. COPYRIGHT: (C)2004,JPO
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