| 摘要 |
PURPOSE:To decrease the number of parts, and to simplify a circuit by using efficiently a capacity body for determining a cut-off frequency and a switch element for switching the cut-off frequency. CONSTITUTION:In a cut-off frequency circuit (for instance, an LPF), the cut-off frequency is determined by a capacity body 7 and a resistor 8, and the capacity body 7 is constituted of a reference capacitor 71 whose capacity is C, and capacitors 72, 73 and 74 having a relation of a capacity 2<n-1>.C [(n) is the num ber of control bits] of a power of the capacity C. In this way, by selecting the closing of a switch element, as for the cut-off frequency, 15 kinds of cut-off frequencies are obtained, extending from 1/2-1/15.
|
