| 摘要 |
A frequency mixing circuit comprises first and second differential pairs Q1, Q2 : Q3, Q4 each formed of two transistors different in emitter area from each other and constant current sources CS1, CS2 for respectively driving the first and second differential pairs. The collectors of the transistors having a large emitter area of K (K > 1) and the collectors of the transistors having a small emitter area of 1 of the first and second differential pairs are respectively connected in common. Between the both differential pairs. the bases of the transistors having an emitter area of K and the bases of the transistors having an emitter area of 1 are respectively connected in common. A first AC signal Vin to be mixed is applied to one of two sets of the commonly connected bases and a second AC signal VLO to be mixed is applied to the other thereof. Thus, the degradation of NF (noise factor) characteristic can be reduced and a good high frequency characteristic can be obtained at a low current. Current mirrors may be included in the collector, load circuits. <IMAGE>
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