Patent ID: 6778785
Filing Date: 2004-08-17
Classification: H04B

Abstract:
A light receiving circuit comprising:a light receiving element to which a voltage is applied, a capacitor connected to one end of said light receiving element for removing a direct current component of an electric signal generated in response to a light received by said light receiving element and outputting an alternating component, low pass filter connected to the other end of said light receiving element for removing the alternating current component of the electric signal generated in response to the light received by said light receiving element and outputting the direct current component as an average received light level, a level shift circuit for shifting the average received light level outputted from said low-pass filter based on a preset reference voltage, and a variable gain amplifier for receiving a voltage of said shifted level as a control voltage and amplifying or attenuating the electric signal of the alternating component outputted from said capacitor with a gain corresponding to said control voltage.