| 摘要 |
PROBLEM TO BE SOLVED: To provide a mutual conductance type filter circuit in which a variable range of a cut-off frequency is expanded. SOLUTION: A current-mirror ratio of a constant current circuit is set to be variable, or the output current of the constant current circuit is made to be variable, or operation states of a plurality of transistors which operate in a constant current region are made to be variable, thereby making the cut-off frequency of the mutual conductance type filter circuit variable. In this way, the variable range of the cut-off frequency can be expanded without impairing constant current characteristics of the transistors. COPYRIGHT: (C)2004,JPO
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