| 摘要 |
<P>PROBLEM TO BE SOLVED: To decrease the number of D-A converters and reduce circuit scales, thereby lowering power consumption. <P>SOLUTION: A digital orthogonal modulation circuit includes an orthogonal modulating means, a D-A converter 17, and a frequency conversion means. The orthogonal modulating means orthogonally modulates local oscillation signals +cosω0t and +sinω0t in accordance with inputted inphase component data I0 and orthogonal component data Q0, respectively, adds up two digital signals I0cosω0t and Q0sinω0t after the orthogonal modulation, and outputs a digital signal (I0cosω0t+QOsinω0t) after the addition. The D-A-converter 17 D-A converts the digital signal (I0cosωOt+Q0sinω0t) from the orthogonal modulating means into an analog signal and outputs the analog signal. The frequency conversion means frequency-converts the analog signal from the D-A converter 17 and outputs this by mixing the analog signal with carrier signals +cosω1t and +sinω1t. <P>COPYRIGHT: (C)2008,JPO&INPIT |
