| 摘要 |
PROBLEM TO BE SOLVED: To obtain a low pass filter circuit for a telephone line in which any tipping can be prevented from being generated in a voice signal band. SOLUTION: In this low pass filter circuit constituted of plural inductors and plural capacitors, inductors L1 and L2 are serially connected with the parallel circuits of inductors L3 and L4 and capacitors C4 and C5, and capacitors C2 and C3 are connected in parallel. In this case, the parallel connection parts of two diodes D1 and D2 and two diodes D3 and D4 are serially connected between the inductors L1 and L2 and the parallel circuits of the inductors L3 and L4 and the capacitors C4 and C5, and the two diodes D1 and D2 and the two diodes D3 and D4 are respectively connected in parallel with the directions of polarity opposite to each other, and the parallel connection parts of the two diodes are respectively set by each unit between an incoming line and an outgoing line, and a capacitor C1 is connected in parallel with the telephone line side when this is viewed from the parallel connection parts of the diodes.
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