| 摘要 |
<p>A communication device which generates transmission signals and reception signals using two oscillators and at the same time minimizes the generation of spurious components. As shown in Figs. 9A, 9B, VCO2's oscillation frequency fVCO2=N (2 fDD), fDD being the difference between transmission frequency fT and reception frequency fR. A signal having a frequency of 3 fDD is output from a 3/(2 N) frequency multiplication circuit. A signal having a frequency of 2 fDD is output from an N divider. The results are that a transmitting intermediate frequency fTIF=3 fDD and a receiving intermediate frequency fRIF=2 fDD. The oscillation frequency fVCO1 of VCO1 is fCH. Therefore, a transmission frequency fT=fCH + fTIF=fCH + 3 fDD. This circuit does not pose a transmission spurious problem with a self-reception band.</p> |
