| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a quadrature demodulator for generating an accurate quadrature phase signal. <P>SOLUTION: The quadrature demodulator is composed of a first and a second mixer circuit 11a and 11b for converting a frequency of a received signal on the basis of a local signal, a first and a second LPF 12a and 12b for removing frequency converted reception signals except for the signals of a desired baseband frequency band, and an error control circuit 13 for controlling an error between output signals from the first and second LPF 12a and 12b. The error control circuit 13 controls the error by generating a sum signal (Q+I signal) and a difference signal (I-Q signal) between signals (I signal and Q signal) having a phase difference of 90° generated by the LPF 12. Then, the sum signal is outputted as a signal of a Q component and the difference signal is outputted as a signal of an I component. Thus, the error reduced accurate quadrature phase signal can be generated. <P>COPYRIGHT: (C)2003,JPO |
