Optical receiving circuit

Abstract

Provided is an optical receiving circuit that reduces a distortion of an output pulse width with respect to an input signal by adjusting the division ratio for a voltage applied to resistors in a resistor network. The optical receiving circuit includes: a differential amplifierthat converts a current signal converted from an optical input L and outputs a non-inverting voltage V+ and an inverting voltage V− whose amplitudes are regulated; a peak detectorthat detects a peak voltage Vp of the non-inverting voltage V+ and outputs the peak voltage Vp; a resistor networkperforming a summation operation based on the peak voltage Vp, the non-inverting voltage V+, and the inverting voltage V− to thereby generate a non-inverting input voltage V+ and an inverting input voltage V− whose oscillations cross each other at the middle points of the amplitudes thereof; a discriminatorthat discriminates a potential at which the oscillations of the non-inverting input voltage V+ and the inverting input voltage V− cross each other, and generates a rectangular signal in accordance with the cross potential; and an adjustment circuitthat, when the non-inverting voltage V+ or the inverting voltage V− is outputted with the amplitude thereof regulated in the differential circuit, adjusts a relative ratio between the voltages connected respectively to resistors of the resistor network, in such a way that the rectangular signal is outputted in the same waveform as the optical input L.