| 摘要 |
A digitized quadrature modulator for receiving of I-channel input digital signal and Q-channel input digital signal, and for quadrature modulating the I-channel and Q-channel input digital signals by a digital signal processing. The modulator has a digital filter (504) for shaping the spectrum of the I-channel and Q-channel input digital signals to provide I-channel and Q-channel output signals, the output signals having a predetermined phase shift between the I-channel and the Q-channel so as to compensate a phase difference based upon the quadrature modulation by the digital signal processing, complementers (505a, 505b) for taking the complement of the I-channel and Q-channel output signals to provide I-channel and Q-channel complement signals, and a multiplexer (505c) for multiplexing the I-channel and Q-channel output signals from the digital filter and the I-channel and Q-channel complement signals from the complementers to provide a quadrature modulated output signal. <MATH> |
