Abstract: A variable gain amplifier includes a differential amplifier circuit having a pair of input terminals and a pair of output terminals, and a first variable attenuation circuit connected between at least one of the pair of input terminals and the pair of output terminals of the differential amplifier circuit and capable of switching a resistance value on the basis of a control signal which is input from the outside.

Abstract: A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

Abstract: A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

Abstract: A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

Abstract: A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.

Abstract: A DC-coupled laser drive circuit (1) includes (i) a voltage drop section (14) provided between a power source and a pre-driver (12) and (ii) a voltage drop amount controlling section (16) for controlling, according to an output of the pre-driver (12), an amount of a voltage drop in the voltage drop section (14).

Abstract: An optical burst signal receiving device includes: a photoelectric conversion unit that photoelectrically converts an input optical burst signal into a current burst signal and outputs the current burst signal; a transimpedance amplifier that converts the current burst signal output from the photoelectric conversion unit into a phase-inverted voltage burst signal; an equalizing amplifier that performs equalizing amplification on the output signal from the transimpedance amplifier and then outputs the resulting signal; a level detection circuit that detects the level of the output signal from the transimpedance amplifier; and an automatic gain control circuit that controls at least one of the transimpedance amplifier and the equalizing amplifier such that the optimum gain is attained for the level of a burst cell detected by the level detection circuit, in which the level detection circuit has: a monitor window generating unit that generates a monitor window signal that regulates a level detection block, which