| 摘要 |
<p>PURPOSE:To suppress mutual interference between a voice line and a data line provided side by side with this voice line by providing a means to control an input impedance and an output impedance. CONSTITUTION:When a switch is turned off, the control terminal of an analog switch 1 to turn an audio signal on/off is pulled up by a resistor 4 of a high impedance and turned to a high level, and the analog switch 1 is turned on. Since a capacitor 3 of large capacity is connected through the resistor 4 to a power source at such a time, the input impedance of the switch circuit is turned to the high impedance. When a switch 2 is turned on, the control terminal of the analog switch 1 is connected to a ground and turned to a low level, and the analog switch 1 is turned off. Since the capacitor 3 is connected to the ground at such a time, the output impedance of the switch circuit is turned to a low impedance.</p> |
