Abstract: The present invention is aimed at providing an output circuit that is of relatively small scale and may perform adjustment to make the output-signal rise slew rate and the fall slew rate equal to each other. An output circuit includes a signal output unit configured to produce at a signal output node a signal that makes transition between a first potential and a second potential, a load circuit having a variable load, and a first switch circuit configured to select one of electrical conduction and non-conduction between the signal output node and the load circuit.

Abstract: An integrated circuit device includes a first power supply domain and a second power supply domain, wherein the first power supply domain includes a first power supply line and a second power supply line, an internal circuit between the first power supply line and the second power supply line, a first clamp circuit that electrically couples between the first power supply line and the second power supply line when a certain potential difference is generated between the first power supply line and the second power supply line, and at least one of a junction element that is between the first clamp circuit and the first power supply line and a junction element that is between the first clamp circuit and the second power supply line, the junction element allowing current to flow when the first clamp circuit becomes electrically conductive.

Abstract: The present invention is aimed at providing an output circuit that is of relatively small scale and may perform adjustment to make the output-signal rise slew rate and the fall slew rate equal to each other. An output circuit includes a signal output unit configured to produce at a signal output node a signal that makes transition between a first potential and a second potential, a load circuit having a variable load, and a first switch circuit configured to select one of electrical conduction and non-conduction between the signal output node and the load circuit.

Abstract: The invention relates to a modulation controlling circuit for supplying a modulating signal to an external modulator that outputs a modulated optical signal, while setting a proper operating point in the external modulator. The external modulator that operates in cooperation with the modulation controlling circuit of the invention enables high-quality modulation at a wide bit rate range. Therefore, in an optical transmission system or a measuring instrument to which the invention is applied, the characteristics and the performance are improved and the operation is made stable without loss of advantages of the external modulator.

Abstract: The optical transmission apparatus for multiple wavelengths according to the present invention comprises; a light source, a temperature control section for controlling the temperature of the light source, a temperature control (ATC) loop for controlling the operation of the temperature control section, and a wavelength control (AFC) loop. The ATC loop detects the temperature of the light source and feedback controls the operation of the temperature control section, so that the optical output wavelengths of the light source fall within a wavelength capture range corresponding to a target wavelength of the AFC loop. The AFC loop has a wavelength detection filter having a periodic transmission wavelength characteristic.

Abstract: The optical transmission apparatus for multiple wavelengths according to the present invention comprises; a light source, a temperature control section for controlling the temperature of the light source, a temperature control (ATC) loop for controlling the operation of the temperature control section, and a wavelength control (AFC) loop. The ATC loop detects the temperature of the light source and feedback controls the operation of the temperature control section, so that the optical output wavelengths of the light source fall within a wavelength capture range corresponding to a target wavelength of the AFC loop. The AFC loop has a wavelength detection filter having a periodic transmission wavelength characteristic.

Abstract: The invention relates to a modulation controlling circuit for supplying a modulating signal to an external modulator that outputs a modulated optical signal, while setting a proper operating point in the external modulator. The external modulator that operates in cooperation with the modulation controlling circuit of the invention enables high-quality modulation at a wide bit rate range. Therefore, in an optical transmission system or a measuring instrument to which the invention is applied, the characteristics and the performance are improved and the operation is made stable without loss of advantages of the external modulator.

Abstract: A transisterized circuit may be driven with a low voltage without saturation of a direct current operating voltage point. The transisterized circuit includes a first transisterized circuit formed by a cascade connection of a first differential transisterized circuit and a first emitter follower circuit, a second transisterized circuit formed by a cascade connection of a second emitter follower circuit and a second differential transistor circuit, and an inversion circuit connected between said first transisterized circuit and said second transistor circuit.

Abstract: An amplifier circuit includes an amplifier which derives an output voltage from an input current, and a bypass circuit which bypasses part of the input current so that the remainder of the input current is applied to the amplifier.

Abstract: A burst optical signal receiver receives optical signals produced in a burst form from a predetermined subscribers. This burst optical signal receiver comprises an identifying circuit for comparing the input level of an input optical signal with a predetermined threshold value to identify the input level; a peak detector for detecting and holding the peak value of the input optical signal; a DC feedback circuit for acquiring the DC level of an output of the identifying circuit; and a circuit for producing the predetermined threshold value from the DC level from the DC feedback circuit and the peak value held in the peak detector and supplying the predetermined threshold value to the identifying circuit. The peak detector has a plurality of peak detection sections having different gains and operational dynamic ranges and causes those peak detection sections to operate in accordance with the input level of the input optical signal.

Abstract: A light receipt system has a bias circuit and a light-receipt element. The bias circuit controls light input power to the light-receipt element to the optimum multiplication factor. The bias circuit of the light-receipt element has a first resistor, a second resistor, and a third resistor. The first resistor and the second resistor are connected in parallel, and the light-receipt element is connected between a connection of the first resistor and the second resistor, and the third resistor. A bypass current path is provided, connected to a junction point between the first resistor and the second resistor.