| 摘要 |
PROBLEM TO BE SOLVED: To obtain an intermediate frequency signal with respect to a desired 1st high frequency signal by suppressing an image signal. SOLUTION: An in-phase distributor 10 distributes a radio frequency signal RF into in-phase signals RF1, RF2 equal in level and phase, and a phase shift distributor 20 distributes a local oscillation signal LO into phase shift signals LO1, LO2 equal in levels and different in phase by 90 degrees. Unit mixers 301, 302 mix the in-phase signals RF1, RF2 and the phase shift signals LO1, LO2, and a phase shifter 40 receives mixed signals MX1, MX2. The phase shifter 40 allows the mixed signals MX1, MX2 to have a phase difference of 90 degrees to generate intermediate frequency signals IF1, IF2, which are given to a differential amplifier 50, where an image signal of an in-phase component is eliminated to output a desired intermediate frequency signal IF. Each of the phased shift distributor 20 and the phase shifter 40 is composed of an integration circuit and a differentiation circuit each consisting of resistors and capacitors to cancell the variation of values of elements, then a high image suppression ratio is maintained.
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