Optical receiver, master station device, optical communication system

An optical receiver to be installed in a master station device that receives an optical signal in a time division multiplexing scheme from a plurality of slave station devices, the master station device being connected to the slave station devices via an optical transmission channel, the optical receiver comprising:

• a photoelectric conversion element to convert the optical signal into a current signal;
• a preamplifier to amplify the current signal output from the photoelectric conversion element and to convert the amplified current signal into a voltage signal;
• a limiting amplifier to further amplify the voltage signal output from the preamplifier and to limit an amplified amplitude of the voltage signal within a predetermined range;
• and
• upper-level circuitry to output a reset signal to the preamplifier in accordance with timing of reception of the optical signal, wherein
• the preamplifier includes
• core amplifier circuitry to amplify the current signal,
• automatic gain control circuitry to change a conversion gain of the core amplifier circuitry by adjusting a first adjustment value,
• single phase differential conversion circuitry to convert a single-phase signal output from the core amplifier circuitry into a differential signal,
• automatic threshold control circuitry to change a threshold for use in the single phase differential conversion circuitry by adjusting a second adjustment value,
• processing circuitry to associate the first adjustment value obtained by adjustment performed by the automatic gain control circuitry on a basis of an output of the core amplifier circuitry and the second adjustment value obtained by adjustment performed by the automatic threshold control circuitry on a basis of the output of the core amplifier circuitry with identification information of a corresponding one of the slave station devices received from the upper-level circuitry, and to store the first adjustment value, the second adjustment value, and the identification information in association with one another in a memory,
• adjustment-purpose core amplifier circuitry to amplify the current signal output from the photoelectric conversion element,
• adjustment-purpose automatic gain control circuitry to change a conversion gain of the adjustment-purpose core amplifier circuitry by adjusting a third adjustment value on a basis of an output of the adjustment-purpose core amplifier circuitry, and
• adjustment-purpose automatic threshold control circuitry to adjust a fourth adjustment value on a basis of the output of the adjustment-purpose core amplifier circuitry,
• the preamplifier updates the first adjustment value stored in the memory using the third adjustment value, and
• the preamplifier updates the second adjustment value stored in the memory using the fourth adjustment value.

An optical receiver to be installed in a master station device that receives an optical signal in a time division multiplexing scheme from a plurality of slave station devices, the master station device being connected to the slave station devices via an optical transmission channel, the optical receiver comprising:

• a photoelectric conversion element to convert the optical signal into a current signal;
• a preamplifier to amplify the current signal output from the photoelectric conversion element and to convert the amplified current signal into a voltage signal;
• a limiting amplifier to further amplify the voltage signal output from the preamplifier and to limit an amplified amplitude of the voltage signal within a predetermined range;
• and
• upper-level circuitry to output a reset signal to the preamplifier in accordance with timing of reception of the optical signal, wherein
• the preamplifier includes
• core amplifier circuitry to amplify the current signal,
• automatic gain control circuitry to change a conversion gain of the core amplifier circuitry by adjusting a first adjustment value,
• single phase differential conversion circuitry to convert a single-phase signal output from the core amplifier circuitry into a differential signal,
• automatic threshold control circuitry to change a threshold for use in the single phase differential conversion circuitry by adjusting a second adjustment value,
• a processing unit to associate the first adjustment value obtained by adjustment performed by the automatic gain control circuitry on a basis of an output of the core amplifier circuitry and the second adjustment value obtained by adjustment performed by the automatic threshold control circuitry on a basis of the output of the core amplifier circuitry with identification information of a corresponding one of the slave station devices received from the upper-level circuitry, and to store the first adjustment value, the second adjustment value, and the identification information in association with one another in a memory,
• signal detection circuitry to detect a signal included in the output of the core amplifier circuitry, and
• a selector capable of switching states between a first state in which an output of the automatic threshold control circuitry is connected to a differential input of the single phase differential conversion circuitry and a second state in which the output of the automatic threshold control circuitry is connected to a single-phase input of the single phase differential conversion circuitry, the states being switched on a basis of a signal detection result of the signal detection circuitry, and
• the selector selects the first state during a time period after the automatic threshold control circuitry changes the threshold using the second adjustment value according to the reset signal until the signal detection circuitry detects a signal, and selects the second state after the signal detection circuitry detects the signal.