| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress an image component in a wide frequency range, and maintain high modulation precision. <P>SOLUTION: The same phase component signal It and a quadrature component signal Qt of a sine wave which are the same frequency and the same amplitude and whose phases intersect are inputed to a quadrature modulator 24 together with a local signal La, the output signal X is converted to a signal Y in an intermediate frequency band by a frequency converter 30, the signal Y is converted to a digital signal, then, is applied with demodulation processing by a quadrature demodulator 33, and the same phase component signal Ir and the quadrature component signal Qr are demodulated. Respective errors of the quadrature modulator 24 and correction values for offsetting the errors are calculated based on these demodulation signals. A control part 40 changes a carrier frequency one by one, and correction values obtained at each carrier frequency are stored in a memory 37. Moreover, when the quadrature modulation signal of the desired carrier frequency is outputed, the control part 40 sets the correction values corresponding to the carrier frequencies in a correction part 22. <P>COPYRIGHT: (C)2007,JPO&INPIT |
