| 摘要 |
PROBLEM TO BE SOLVED: To prevent malfunction of a duplicate APC circuit by adding a latching circuit and a waveform-shaping circuit so as to correctly generate an alarm with respect to a same level input of a data signal and outputting the alarm, only at an abnormal input of a data signal and a clock signal. SOLUTION: An output voltage Vout has a hysteresis characteristics with respect to an input voltage Vin. When the amplitude of the voltage Vin is Vt or over, the voltage Vout is switched in matching with an input signal with the voltage Vin, when the amplitude of the voltage Vin is less than the voltage Vt, the voltage Vout is not switched. When the amplitude of the voltage Vin is the voltage Vt or higher, an output signal that is waveform-shaped by a waveform shaping circuit 11 is switched in matching with the received data signal, the level is converted into an intermediate level by an averaging circuit and no alarm is outputted. When the amplitude of the voltage Vin is less than the voltage Vt, the output signal of the waveform shaping circuit 11 is a DC, and the output of the averaging circuit turns into a DC H level or L level and an alarm is issued. |
