| 摘要 |
PURPOSE:To reduce the number of components of the titled circuit by connecting plural circuits whose cut-off frequency is the same in cascade, and providing a variable Q means for each circuit part. CONSTITUTION:Filter circuit parts 7-9 having the same cut-off frequency are connected and variable Q means 10-12 varying the Q are provided to the circuit parts 7-9 respectively. Let the Q selection number by the means 10, 11, 12 be n1, n2 and n3 respectively, the number of Qs being selected of the entire filter circuit is given as n1Xn2Xn3. Four capacitors, 4 switches and a control circuit to turn on/off the switches are required to constitute the Q variable means, the constitution of the control circuit is comparatively simple and the number of component is less. When the number of Qs being selected to be required is increased, it is coped with the increase in the number of filter circuit parts connected in cascade.
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