| 摘要 |
PURPOSE:To prevent characteristics from varying with ambient temperature by providing two variable resistance elements which are substantially equal in characteristic varying in resistance value with a control signal, varying a control voltage and thus varying the resistance value of the 1st variable resistance element accurately, and making the resistance value of the 2nd variable resistance element follow up the variation in the control voltage. CONSTITUTION:An operational amplifier 5 amplifies the difference between signals impressed to its two input terminals and outputs an error output (v). A converter 6 receives the error output (v) and outputs a control signal Y of a voltage, a current, light, or magnetism. The 1st and the 2nd variable resistance elements 30 and 40 vary in resistance value by receiving the same control signals Y, and their characteristics of resistance variation are substantially equal. The resistance value RY of the 1st and the 2nd variable resistance elements 30 and 40 is optionally controllable with the control voltage Vc. No matter how ununiform characteristics of the 1st and the 2nd variable resistance elements 30 and 40 in a pair are as compared with another pair, both elements have resistance values corresponding to the control voltage Vc on condition the characteristics of both elements are substantially the same as a pair.
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