US Patent 7557333 Optical signal receiving circuit and optical signal receiving apparatus

An optical signal receiving circuit has a current-voltage converting circuit which receives the output current signal of a photoelectric converting circuit, converting an optical signal into the current signal, and converts the current signal into a voltage signal. A differential circuit in the subsequent stage to the current-voltage converting circuit uses a resistor as its current source to facilitate setting of an operating voltage level in the circuit. To eliminate an adverse effect of asymmetry of the output waveform from the differential circuit due to the use of the resistor, the reference voltage level as the other input to the reference circuit is generated from the output voltage signal of the current-voltage converting circuit by a voltage generating circuit incorporating a feed-forward-controlling connection. Thus, coexistence of high bandwidth characteristics and broad dynamic range having so far been difficult to attain by low voltage apparatus can be realized.