| 摘要 |
PROBLEM TO BE SOLVED: To eliminate leakage of a carrier as much as a level equivalent to a desired signal level without decreasing a level of a modulation signal by using one orthogonal modulator for a modulation purpose, using the other orthogonal modulator for a purpose of generating a carrier leakage elimination signal and using an adder to sum output signals of both the modulators. SOLUTION: A signal distributor 1 distributes a carrier signal C into two identical signals the one is given to an orthogonal modulator 10 and the other is given to an orthogonal modulator 20. The orthogonal modulator 10 modulates an I signal and a Q signal and the orthogonal modulator 20 generates a carrier leakage elimination signal S2 to eliminate an offset error. That is, the orthogonal modulator 20 modulates an modulation output S1 obtained by the orthogonal modulator 10 and including an offset error with a DC bias having the same amplitude as that of a carrier leakage component of the I signal and of opposite polarity and with a DC bias having the same amplitude as that of a carrier leakage component of the Q signal and of opposite polarity and an attenuator 21 applies fine-adjustment to its output S2 and an adder 2 sums the outputs S1, S2. |
