| 摘要 |
PROBLEM TO BE SOLVED: To provide a gain controller which enables high-accuracy, wide-range gain control, with a simple and inexpensive constitution, without requiring high-accuracy gain control means and any arithmetic means for performing logarithmic compression. SOLUTION: This gain controller has a 1st differential circuit 31 constituted including 1st and 2nd current sources 1 and 2 which have different current values, and the current outputted by the 1st differential circuit 31 is converted by diodes 13 and 14 into a voltage and the gain of the input current is determined by the 2nd differential circuit 34 according to the potential difference between the diodes 13 and 14. Consequently, the gain varies at a constant ratio through constant variation in gain control voltage, and gain control can be performed over a wide range with high accuracy.
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