| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency converting circuit for simultaneously realizing the reduction in the voltage, current, and noise and a high conversion gain, and for reducing the deterioration of a noise figure against the fluctuation of a local oscillation signal. SOLUTION: In this frequency converting circuit 100, output of thermal noise generated from eighth and ninth resistances 18 and 19 connected with the bases of the second and third differential transistor pairs 12 and 13 is multiplied by a difference in gain between second and third differential transistor pairs 12 and 13, then the influence of the thermal noise generated from the eighth and ninth resistances 18 and 19 is offset and does not appear in the output when the gains of the second and third transistor pairs 12 and 13 are made equal. That is, the load resistances of the second and third differential transistor pairs 12 and 13 are adjusted so that the gains of the second and third differential transistor pairs 12 and 13 can be made equal. Thus, any thermal noise signal generated by the eighth and ninth resistances 18 and 19 can not be outputted.
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