| 摘要 |
PROBLEM TO BE SOLVED: To obtain a quadrature modulation circuit capable of cancelling a DC component generated by D-A conversion without delay by increasing a response speed to cancel a DC component in an unadjusted circuit configuration. SOLUTION: A quadrature modulation IC 3 with differential input signal terminals which has input terminals I, Q of orthogonally crossing base-band signals I1, Q1 and differential input signal terminals IN, QN is used as a quadrature modulator. A DC component abstracted from the signals I1, Q1 by low-pass filters 6, 16 is inputted into terminals IN, QN of the modulation IC 3. Thus, a carrier leakage can be reduced with a simpler configuration.
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