| 摘要 |
PROBLEM TO BE SOLVED: To decrease the NF(noise factor) without changing the CG (conversion gain) nor Q characteristic of a mixer circuit by providing a control means between a tuning circuit and an intermediate frequency terminal of the mixer circuit to perform the tuning control of the Q characteristic of the mixer circuit. SOLUTION: This frequency conversion circuit 11 consists of a mixer circuit consisting of a multiplication circuit and two pieces of Q value tuning control resistors RX which are connected to an intermediate frequency output terminal of the mixer circuit. These resistors RX are connected in series between both connection ends of a tuning circuit 14 and the collectors which construct a 2nd differential connection circuit 13b, i.e., between the circuit 14 and an IF amplifier 12 serving as the intermediate frequency output of the mixer circuit. Thus, the tuning control is carried out for the Q characteristic of the mixer circuit by the resistaces RX which are placed between the mixer circuit and the intermediate frequency output terminal of the mixer circuit. That is, the resistances RX function as the control means which perform the tuning control of Q characteristic of the mixer circuit.
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