Frequency conversion circuit and radio communication apparatus with the same

A radio communication equipment comprising:

• a first frequency conversion circuit for receiving a reception signal sent from one of a plurality of radio equipments of different frequency bands and converting the reception signal to a first intermediate frequency signal having a frequency lower than that of the reception signal;
• a second frequency conversion circuit including a sampling circuit for sampling the first intermediate frequency signal in accordance with a predetermined sampling frequency signal to output a second intermediate frequency signal, and a sampling signal generator for outputting the sampling frequency signal to the sampling circuit, the sampling frequency signal having a frequency determined so that an integer multiple of not less than three times the sampling frequency is outside a frequency range of the first intermediate frequency;
• and
• demodulating means for demodulating the second intermediate frequency signal.

A radio communication equipment comprising:

• a filter for band-limiting received signals of different frequency bands;
• a frequency conversion circuit including a sampling circuit for sampling the received signal band-limited by said filter, in accordance with a predetermined sampling frequency signal to output an intermediate frequency signal, and a sampling signal generator for outputting the sampling frequency signal to said sampling circuit, the sampling frequency signal having a frequency determined so that an integer multiple of not less than three times the sampling frequency is outside a frequency range of the received signal;
• and
• demodulating means for demodulating the intermediate frequency signal.

A radio communication equipment comprising:

• a first frequency conversion circuit which includes a first sampling circuit for receiving one of a plurality of reception signals of different frequency bands and sampling the one of the reception signals in accordance with a first sampling frequency signal to output a first intermediate frequency signal, and a first sampling signal generator for supplying the first sampling frequency signal to said first sampling circuit, the sampling frequency signal having a frequency determined so that an integer multiple of not less than three times the sampling frequency is outside a frequency range of the first intermediate frequency signal;
• a second frequency conversion circuit including a second sampling circuit for sampling the first intermediate frequency signal in accordance with a second sampling frequency signal to output a second intermediate frequency signal, and a second sampling signal generator for outputting the second sampling frequency signal to said sampling circuit, the second sampling frequency signal having a frequency determined so that an integer multiple of not less than three times the second sampling frequency signal is outside a frequency range of the first intermediate frequency signal;
• and
• demodulating means for demodulating the second intermediate frequency signal.

A radio communication equipment comprising:

• a first frequency conversion circuit which includes a sampling circuit for receiving one of a plurality of reception signals of different frequency bands and sampling the one of the reception signals in accordance with a sampling frequency signal to output a first intermediate frequency signal, and a sampling signal generator for supplying the sampling frequency signal to said sampling circuit, the sampling frequency signal having a frequency determined so that an integer multiple of not less than three times the sampling frequency is outside a frequency range of the first intermediate frequency signal;
• a second frequency conversion circuit for frequency-converting the first intermediate frequency signal in accordance with a predetermined frequency signal to output a second intermediate frequency signal;
• and
• demodulating means for demodulating the second intermediate frequency signal.