| 摘要 |
PURPOSE: An analog SLIC(Subscriber Line Interface Circuit) for an exchange subscriber board is provided to implement SLIC functions in the analog circuit applying a general OP amplifier and a relay in the exchange subscriber board, thereby reducing a cost. CONSTITUTION: A relay(110) transmits signals incoming from a TIP terminal and a RING terminal to the other end, transmits a ring signal inputted from a ring signal generator to the RING terminal, and transmits an external signal to the TIP terminal and the RING terminal. A logic circuit(120) combines signals inputted from an RR terminal and a DET terminal, and outputs a control signal for controlling a switching process of the relay(110). A comparator(130) compares size of the signals incoming from the TIP terminal and the RING terminal, and outputs the signals to the DET terminal. A low pass filter(140) filters AC components of the signal incoming from the TIP terminal. A differential amplifier(150) differentially amplifies the signals of the TIP and the RING terminals, and outputs the signals to a TX terminal. An inverting amplifier(160) inversely amplifies the signals, and outputs the signals. A current amplifier(170) amplifies currents of the outputted signals, and outputs the signals to the TIP and the RING terminals.
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