1. Field of the Invention
The present invention relates to an optical receiver applied to an optical transmission system, and an optical transmission system.
2. Description of the Related Art
A transimpedance amplifier (TIA) to convert current to a voltage is used in an optical transmission system.
The optical transmission system refers to a system in which data arising from optical conversion of an electrical signal is transmitted from an optical transmitter (TX) and the optical data received by an optical receiver (RX) is converted to an electrical signal.
A photodiode (PD) converts the optical data sent from the optical transmitter (TX) to a current and the TIA is used to convert this current to a differential voltage.
The electrical signal output from a driver of the optical transmitter (TX) is converted to an optical signal by an electro-optical conversion element, a laser diode (LD) or a vertical cavity surface emitting laser (VCSEL). This optical signal passes through an optical fiber to be subjected to opto-electrical conversion by the PD of the optical receiver (RX).
In the communication from the optical transmitter (TX) to the optical receiver (RX), power loss at the connection part of the optical fiber and in the electrical/optical conversion and the optical/electrical conversion is large and the output current of the PD has significantly-low amplitude in some cases. Thus, it is preferable for the TIA to have a high signal-to-noise ratio (SNR).