| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit which does not deteriorate transmitting modulation characteristics by building a VCO for generating a frequency of twice as large as a transmitting output frequency in a semiconductor integrated circuit device, for transmitting in a mobile radio set and building a filter for removing an unnecessary harmonic signal from a transmitting output in it. SOLUTION: The signal generated from the built-in VCO 1 is divided in frequency into 2 by a frequency divider 2, and a 0°/90°phase shifting signal is generated. A transmitting modulation signal of both phases made by quadrature modulating the signal from a base band signal input terminal 4 by a quadrature modulator 3 is generated. Aπtype harmonic signal removing filter 11 is provided. The GND of the filter has a special purpose GND terminal 18. Consequently, the wraparound of the signal particularly having twice as large as the transmitting output frequency to the built-in VCO is reduced. The deterioration of the transmitting modulation characteristics can be prevented. COPYRIGHT: (C)2006,JPO&NCIPI
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