Patent ID: 8280262

Claim:
A light receiving circuit comprising: a light receiving element that receives an optical signal and converts into electrical signal; a comparator that receives information about the optical signal through the light receiving element and generates a pulsed signal based on the received information; a band limit circuit disposed between the light receiving element and the comparator, the band limit circuit removing noise components of frequency higher than the pulsed signal, and generating an input voltage to be input to the comparator; and a comparator threshold circuit disposed between the light receiving element and the comparator, the comparator threshold circuit generating a threshold voltage to be input to the comparator, and controlling the threshold voltage to be input to the comparator within a binary range, wherein the band limit circuit comprises: a switch circuit that operates at a given clock frequency; a first capacity that integrates an electric charge of the voltage input to the band limit circuit during a sampling period; a second capacity to which the voltage input to the band limit circuit is connected and in which the transfer of the electric charge of the first capacity is performed during a hold period, the electric charge of the first capacity being separated from the voltage input to the band limit circuit; and amplification means connected to the second capacity, the amplification means outputting the voltage input to the comparator.