| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable resistance circuit with which the variance in the manufacture of integrated circuits and the influence of ambient temperatures can be offset, and to provide application circuits using the variable resistance circuit. SOLUTION: The circuit is provided with a control circuit 10 having two constant-current sources 12 and 13 of which constant-current ratio is varied by an electrical signal to be applied to a control terminal 5 with a signal, an operational amplifier 7, a resistor 9, and two MOS transistors 6 and 8 having their gates connected in common. Then, one output terminal of the control circuit is connected to one end of the resistor and to an inverted input terminal of the operational amplifier, and the other output terminal of the control circuit is connected to the drain of the MOS transistor 6 connected at the gate thereof to an output terminal of the operational amplifier and to the non-inverted input terminal of the operational amplifier. Then, the other end of the resistor and the source of the MOS transistor 6 are connected to a reference voltage terminal 4, the MOS transistor is operated in a triode region, and a portion between the source and the drain of the MOS transistor 8 connected at the gate thereof to the output terminal of the operational amplifier and connected at the source thereof to the reference voltage terminal directly or via a voltage copy circuit 11 is used as an equivalent resistance. COPYRIGHT: (C)2003,JPO
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