| 摘要 |
A frequency mixing circuit which comprises first to fourth unbalanced differential pairs Q1 - Q8 each composed of two transistors whose emitter area ratio is K:1( K > 1), and first to fourth transistors Q9 - Q12 each for driving the pairs. In the first and second pairs Q1 - Q4, the bases of the transistors Q1, Q3 having each smaller and larger emitter areas are connected to form a first input terminals pair. In the third and fourth pairs Q5 - Q8, the bases of the transistors Q5, Q7 having each smaller and larger emitter areas are connected to form a second input terminals pair. The respective one terminals of the first and second input terminals pairs are connected to be applied with a signal voltage VRF. The respective other terminals of the first and second input terminals pairs are respectively applied with voltages +/- (1/2) VAGC. The bases of the first to fourth transistors are applied with a signal voltage VLO. Wide range AGC function can be provided stably. <IMAGE>
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