| 摘要 |
PROBLEM TO BE SOLVED: To remove image signals without fail, in a frequency conversion circuit that uses a sub-harmonic mixer. SOLUTION: In a frequency conversion part 30, a phase shift circuit 31 converts a received signals, RF signals into signals RF1, RF2 having 90 degrees for the phase differences; mixers 34a, 34b multiplies (or combines) each of the signals RF1, RF2 by a locally-generated signal Lo generated by a locally-generated signal-generating section 32; LPF35a, 35b extract a signal for a difference frequency ¾F<SB>RF</SB>-F<SB>Lo</SB>×N¾ with Nth harmonic for the RF signal and locally-generated signal Lo; and a PPF36 removes the image signal to output as an IF signal of a desired frequency. COPYRIGHT: (C)2011,JPO&INPIT
|
