| 摘要 |
PURPOSE:To prevent the fluctuation of a slice level from being caused even if the characteristic of an active element is varied by supervising the output of an equalizing amplifier, and slicing the output by applying the linear amplification when the output is at the reference slice level or over, and holding the value equal to the slice level when the output is at the reference slice level or below. CONSTITUTION:A nonlinear amplifier 14 consists of a linear amplifier (amplifier and switch circuit) 24 and a comparator 26. The amplifier 24 amplifies linearly an input signal when an input signal S3 is higher than the slice level, and has a characteristic holding an amplifier output voltage at a level equal to the slice level when the input signal is lower, and the comparator 26 receives the input signal S3 and a voltage VB for deciding slice level from a reference voltage source 20 and executes the changeover control for the amplifier 24. Differential pair transistors (TRs) 32, 34 flow an equal current when S3=SB. The comparator 26 changes over a switch 42 in the position of the contact (b) when S3<=VB to connect a constant current source 44 to a resistor 46. Thus, the S3-VB is amplified linearly when S3>VB and an output at S3=VB is held when S3<=VB. |
