| 摘要 |
PROBLEM TO BE SOLVED: To suppress fluctuation of input impedance due to a gain control voltage. SOLUTION: A variable gain circuit is constituted so that gains are outputted only from the output terminals Vout, Voutx of one variable gain circuit by connecting input terminals Vin, Vinx of two variable gain circuits 1, 2 to vary the gains by the gain control voltage to be provided in a gain control terminal in parallel. Each of the variable gain circuits 1, 2 is operated opposite to each other against the gain control voltage Vcd here.
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