| 摘要 |
PURPOSE:To obtain the frequency mixer circuit with less number of components and operated at a low voltage. CONSTITUTION:Transistors(TRs) Q1, Q2 and Q4, Q3 respectively form unbalanced differential pairs in which a size (area) ratio of emitters connected in common is K:1 (K>1) and they are driven respectively by a constant current source I0 A 1st AC signal (voltage VIN) is applied to bases of one pair and a 2nd AC signal (voltage VLO) is applied to bases of the other pair. Collectors of the Q1, Q4 and collectors of the Q2, Q3 are respectively connected in common, and a collector current I2 of the one connection is extracted as a voltage through a load resistor RL as an output voltage VO. The relation of I1=I+(1/2)DELTAI and I2=I-(1/2)DELTAI is in existence, and a difference DELTAI=I1-I2 includes components of sum and difference of two frequencies fIN and fLO. Since the relation of VO=VCC-RL.I2 exists, the components of the sum and difference of the two frequencies fIN and fLO are converted into a voltage by the load resistor RL.
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