| 摘要 |
A receiver of the direct conversion system by which problems arising from interference between a reception signal and a local signal used by a quadrature demodulator on the reception side are moderated. Where the carrier frequency of a transmission signal is represented by f<SUB>t </SUB>and the carrier frequency of a reception signal by f<SUB>r </SUB>while the frequency interval between the transmission and reception carrier frequencies is represented by f<SUB>s </SUB>(=f<SUB>r</SUB>-f<SUB>t</SUB>), first and second local oscillators generate first and second local signals f<SUB>LO1</SUB>, f<SUB>LO2 </SUB>having frequencies f<SUB>LO1</SUB>≈f<SUB>t</SUB>-f<SUB>s </SUB>and f<SUB>LO2 </SUB>≈2.f<SUB>s</SUB>, respectively. A mixer mixes the first and second local signals to generate an internal local signal which is a sum frequency component. The internal local signal is supplied to a quadrature demodulator of the reception side. The mixer and a band-pass filter are formed in the same LSI chip as the quadrature demodulator.
|
