| 摘要 |
PURPOSE:To improve a maximum input level for normal operation by adding a clamp circuit to limit an output signal of a preamplifier to a prescribed amplitude to the reception circuit. CONSTITUTION:A clamp circuit 5 to limit an output signal of a preamplifier 2 to a prescribed amplitude is provided to the reception circuit. Thus, the linearity of a gain variable amplifier 3 is lost by allowing the clamp circuit 5 to clamp an output level of the preamplifier 2 to be less than a maximum drive amplitude and a maximum input amplitude of the gain variable amplifier 3, but the waveform distortion in the preamplifier 2 and the gain variable amplifier 3 is minimized and malfunction of an identification recovery circuit 4 at a post-stage is avoided. Thus, the maximum optical input level for normal operation is improved. |
