Patent ID: 8463211

Claim:
A radio frequency signal receiving apparatus, comprising: a first poly-phase filter, receiving a radio frequency input signal and thereby producing a plurality of filtered radio frequency signals; a first frequency-mixer module, coupled to the first poly-phase filter for conducting frequency-mixing operation on the filtered radio frequency signals according to a reduced-frequency signal so as to produce a plurality of reduced-frequency radio frequency signals; a first switch, receiving the reduced-frequency radio frequency signal and transmits the reduced-frequency radio frequency signal to a first channel or a second channel according to a selection signal; a second poly-phase filter, coupled to the first switch and receiving the reduced-frequency radio frequency signal transmitted by the second channel so as to conduct filtering operation; a low-pass filter module, coupled to the second poly-phase filter and the first switch and receiving the reduced-frequency radio frequency signal transmitted by the first channel to conduct low-pass filtering operation and further produce a low-intermediate-frequency signal or a zero-intermediate-frequency signal, the low-pass filter module comprises: a first low-pass filter, coupled to the first switch and the second poly-phase filter for receiving the output of the second poly-phase filter and conducting low-pass filtering operation on the received output or for conducting low-pass filtering operation on a portion of the reduced-frequency radio frequency signal transmitted by the first channel; a second low-pass filter, coupled to the first low-pass filter and the first switch for receiving another portion of the reduced-frequency radio frequency signal transmitted by the first channel and conducting low-pass filtering operation on the received another portion or for conducting low-pass filtering operation on the output of the first low-pass filter; and a second switch, coupled between the first low-pass filter and the second low-pass filter for turning on or off the connection between the first low-pass filter and the second low-pass filter, wherein, when the first low-pass filter receives the output of the second poly-phase filter while the second low-pass filter receives the output of the first low-pass filter and the first low-pass filter and the second low-pass filter respectively conduct low-pass filtering operation on the received signals, the low-pass filter module produces the low-intermediate-frequency signal; and a reducing-frequency voltage controlled oscillator, coupled to the first frequency-mixer module for producing the reduced-frequency signal.