| 摘要 |
PURPOSE:To decrease the number of constituent elements greatly and to accelerate the economization and size reduction of a subscriber circuit by setting the impedance values of the 3rd and the 1st impedance elements equal to each other or N times as large as it, and setting the impedance value of the 5th impedance element equal to or N times as large as the impedance value of a two-wire circuit. CONSTITUTION:The impedance value of a two-wire subscriber circuit which is viewed from two-wire terminals 2A and 2B is denoted as Z2, impedance values of impedance elements 31-34 are equalized to Z1, and impedance values of impedance elements 35-37 are set to Z2. Consequently, the two-wire and four-wire converting circuit is constituted by using only two operational amplifiers 22 and 23 and five impedance elements 31-36 so that a voltage Vzi inputted to the two-wire terminals 2A and 2B is transmitted to a four-wire transmission output terminal 4F and a voltage V4i applied to a four-wire reception input terminal 4B is transmitted to the two-wire terminals 2A and 2B without being transmitted to the four-wire transmission output terminal 4F. |
