| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect an NRZ signal in small amplitude by setting an appropriate offset voltage.SOLUTION: An NRZ signal amplifier 2 includes: an offset circuit 11 for adding an NRZ signal and an offset voltage, and outputting it; a main amplifier 12 for amplifying an output signal of the offset circuit 11 and outputting mutually inverted two signals; input side voltage detection means 13 for detecting a high level voltage and a low level voltage of an input signal of the main amplifier 12; output side voltage detection means 14 for detecting the mutually inverted two signals; and offset voltage control means 15 for calculating a center voltage between a detected high level voltage and a low level voltage, setting an offset voltage to the offset circuit 11 so as to the center voltage becomes approximately the center of proper input range for the main amplifier 12, performing fine tuning of the offset voltage so as to a voltage difference between the mutually inverted two signals approaches to zero on the basis of the voltage difference and polarity change point.</p> |
