| 摘要 |
PROBLEM TO BE SOLVED: To improve communication performance by making the cutoff frequency of an HPE and the cutoff frequency of an LPF lower than the cutoff frequency of a stabilizing circuit. SOLUTION: The cutoff frequency of the HPF 2 and the cutoff frequency of the LPF 5 are set much lower than the cutoff frequency of a voltage regulator 6. When the line-directional impedance is observed from a transmitting and receiving means 3 in a connection relation such as this, the parallel impedance of the cascaded impedance between a diode bridge 1, a telephone line through the HPF 2, and a station and cascaded impedance of the LPF 5 and voltage regulator 6 is seen. With characteristics like this, the impedance observed from the transmitting and receiving means 3 eventually has the impedance value of a line load passed through the HPF 2, so that the phenomenon where a transmit signal is absorbed by a power receiving circuit as a load is not generated in a frequency band in which the output of the transmitting and receiving means 3 decreases.
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