Patent ID: 8884208

Claim:
A light receiving circuit comprising: a trans-impedance amplifier which includes a photodiode to convert an optical signal into an electrical signal, a feedback resistor, a first current generating unit, and a first N channel transistor, one end of the photodiode being connected to a power supply line of a lower potential side, one end of the feedback resistor being connected to the other end of the photodiode, one end of the first current generating unit being connected to a power supply line of a higher potential side, the other end of the first current generating unit being connected to the other end of the feedback resistor and a drain of the first N channel transistor, a gate of the first N channel transistor being connected to the other end of the photodiode, a source of the first N channel transistor being connected to the power supply line of the lower potential side; an output circuit which includes a second current generating unit and a second N channel transistor and outputs an output signal from the drain of the second N channel transistor, one end of the second current generating unit being connected to the power supply line of the higher potential side, the other end of the second current generating unit being connected to a drain of the second N channel transistor, a gate of the second N channel transistor being connected to the drain of the first N channel transistor, a source of the second N channel transistor being connected to the lower potential side; and a first P-channel transistor, wherein the first current generating unit includes a second P-channel transistor, the second current generating unit includes a third P-channel transistor, a gate of the first P-channel transistor is connected to a drain of the first P-channel transistor and gates of the second and the third P-channel transistors, and the first, the second and the third P-channel transistors constitute a current mirror circuit.