Abstract: A power-supply noise measuring circuit includes a voltage fluctuation detecting circuit, a unit time generating circuit, a current measuring circuit, and a sampling circuit. The voltage fluctuation detecting circuit generates a detection current in accordance with a voltage fluctuation of a power supply. The unit time generating circuit generates a unit time in accordance with a clock signal. The current measuring circuit treasures an amount of the detection current per unit time. The sampling circuit samples the amount of the detection current measured by the current measuring circuit, every unit time. The present invention provides the power-supply noise measuring circuit that has a small circuit area and enough accuracy.

Abstract: Current reading means detects an output current of a current source whose output current varies with a variation in temperature and outputs a value proportional to the output current. The temperature of the current source corresponding to the output value of the current reading means which is proportional to the output current of the current source is measured, and a parameter for converting the output value to temperature information is determined from the output value of the current reading means and the measured value of the temperature of the current source corresponding to the output value. The output value of the current reading means is converted to the temperature information using the determined parameter.

Abstract: A power supply noise reduction circuit and a power supply noise reduction method for reducing power supply noise at any frequency, includes forcing a power supply noise to resonate to the resonance frequency of a parallel resonance circuit, including an inductor and a capacitor to set the frequency of the noise equal or close to the resonance frequency of the parallel resonance circuit and, attenuating the noise, set equal or close to the resonance frequency of the parallel resonance circuit, using a low-pass filter including a resistor and a capacitor.

Abstract: An apparatus includes a current source, a current monitor circuit which monitors a current amount of the current source, and outputs a current amount signal corresponding to the current amount being monitored, a counter circuit which counts a count value based on the current amount signal, the count value corresponding to a period being taken until when the current amount reaches a predetermined value, and a control circuit which modifies an operation parameter for operating a circuit unit according to the count value.

Abstract: A power-supply noise measuring circuit includes a voltage fluctuation detecting circuit, a unit time generating circuit: a current measuring circuit, and a sampling circuit. The voltage fluctuation detecting circuit generates a detection current in accordance with a voltage fluctuation of a power supply. The unit time generating circuit generates a unit time in accordance with a clock signal. The current measuring circuit treasures an amount of the detection current per unit time. The sampling circuit samples the amount of the detection current measured by the current measuring circuit, every unit time. The present invention provides the power-supply noise measuring circuit that has a small circuit area and enough accuracy.

Abstract: Current reading means detects an output current of a current source whose output current varies with a variation in temperature and outputs a value proportional to the output current. The temperature of the current source corresponding to the output value of the current reading means which is proportional to the output current of the current source is measured, and a parameter for converting the output value to temperature information is determined from the output value of the current reading means and the measured value of the temperature of the current source corresponding to the output value. The output value of the current reading means is converted to the temperature information using the determined parameter.

Abstract: An apparatus includes a first sequential circuit which captures an input signal according to a first clock signal, a second sequential circuit which captures the input signal according to a second clock signal and outputs the captured input signal to a logic circuit, the second clock signal being modulated so that a period of the second clock signal is shorter than that of the first clock signal, a third sequential circuit which captures an output signal of the logic circuit according to the second clock signal, and a verification circuit which verifies whether an output signal of the first sequential circuit and an output signal of the third sequential circuit match with each other.

Abstract: A temperature measurement circuit includes a diode including a pair of terminals between which a constant voltage is applied and passing therethrough a current that changes depending on a temperature; and a temperature detection section that detects the temperature based on the current passing through the diode. The temperature measurement circuit measures the temperature with a higher accuracy.

Abstract: A power supply noise measuring circuit and measuring method are provided which are capable of evaluating a frequency component of power supply noise that affects performance and functions in a circuit by using a cross-correlation function. The power supply noise measuring circuit includes a SIN wave generating circuit which generates a sine wave signal having a variable frequency in a constant amplitude, a cross-correlation processing circuit which calculates and output a cross-correlation function between power supply noise and a sine wave signal fed from the SIN wave generating circuit, a comparator which compares a cross-correlation function output with a specified threshold voltage and which generates an output when the cross-correlation function output exceeds the threshold voltage, and a counter which counts the number of occurrences of the output from the comparator within a specified time of period.

Abstract: An apparatus includes a current source, a current monitor circuit which monitors a current amount of the current source, and outputs a current amount signal corresponding to the current amount being monitored, a counter circuit which counts a count value based on the current amount signal, the count value corresponding to a period being taken until when the current amount reaches a predetermined value, and a control circuit which modifies an operation parameter for operating a circuit unit according to the count value.

Abstract: An apparatus includes a first sequential circuit which captures an input signal according to a first clock signal, a second sequential circuit which captures the input signal according to a second clock signal and outputs the captured input signal to a logic circuit, the second clock signal being modulated so that a period of the second clock signal is shorter than that of the first clock signal, a third sequential circuit which captures an output signal of the logic circuit according to the second clock signal, and a verification circuit which verifies whether an output signal of the first sequential circuit and an output signal of the third sequential circuit match with each other.

Abstract: To provide a signal measuring circuit that measures a signal, such as noise, with high precision. A maximum reference value and a minimum reference value are generated based on the voltage level of a signal, the voltage difference between the maximum reference value and the minimum reference value is divided, a reference value is generated according to the divided voltage, and the voltage level of the signal is compared with the reference value, thereby measuring the signal.

Abstract: A power supply noise measuring circuit and measuring method are provided which are capable of evaluating a frequency component of power supply noise that affects performance and functions in a circuit by using a cross-correlation function. The power supply noise measuring circuit includes a SIN wave generating circuit which generates a sine wave signal having a variable frequency in a constant amplitude, a cross-correlation processing circuit which calculates and output a cross-correlation function between power supply noise and a sine wave signal fed from the SIN wave generating circuit, a comparator which compares a cross-correlation function output with a specified threshold voltage and which generates an output when the cross-correlation function output exceeds the threshold voltage, and a counter which counts the number of occurrences of the output from the comparator within a specified time of period.

Abstract: To provide a signal measuring circuit that measures a signal, such as noise, with high precision. A maximum reference value and a minimum reference value are generated based on the voltage level of a signal, the voltage difference between the maximum reference value and the minimum reference value is divided, a reference value is generated according to the divided voltage, and the voltage level of the signal is compared with the reference value, thereby measuring the signal.

Abstract: According to one embodiment, a signal from a power supply line is caused to pass through a high pass filter, and a first signal is generated by adding a voltage-divided signal to the signal. In addition, a second signal obtained by adding the voltage-divided signal to an identification voltage is generated. A comparator outputs a comparison result of comparing a voltage of the first signal with a voltage of the second signal, and a counter counts up a count value when the voltage of the first signal is higher than that of the second signal. A sample hold circuit sample-holds the count value just before the counter is reset.

Abstract: A power supply noise reduction circuit and a power supply noise reduction method for reducing power supply noise at any frequency, includes forcing a power supply noise to resonate to the resonance frequency of a parallel resonance circuit, including an inductor and a capacitor to set the frequency of the noise equal or close to the resonance frequency of the parallel resonance circuit and, attenuating the noise, set equal or close to the resonance frequency of the parallel resonance circuit, using a low-pass filter including a resistor and a capacitor.

Abstract: According to one embodiment, a signal from a power supply line is caused to pass through a high pass filter, and a first signal is generated by adding a voltage-divided signal to the signal. In addition, a second signal obtained by adding the voltage-divided signal to an identification voltage is generated. A comparator outputs a comparison result of comparing a voltage of the first signal with a voltage of the second signal, and a counter counts up a count value when the voltage of the first signal is higher than that of the second signal. A sample hold circuit sample-holds the count value just before the counter is reset.

Abstract: This invention provides a vertical-cavity surface-emitting laser device comprising a surface light-emitting part comprising a cavity consisting of two multilayer reflectors and an active region between them and a waveguide part for introducing induced light into the surface light-emitting part. The device is substantially independent of a temperature and allows a wavelength to be controlled after manufacturing the device.

Abstract: A system that affords synchronization signals for adjusting the skew in parallel transmission without producing data overhead to enable high-efficiency large-capacity transmission. On a transmitter side, a transmitter outputs two wavelengths. The transmitter transmits the data signals for transmission as it switches from a first wave length to a second wavelength at a certain synchronization timing. A wavelength filter separates a first wavelength and a second wavelength on a receiving side at the pre-stages of receivers receiving the data signals of the respective transmission paths. Data D1 and D2, separated in association with the first and second wave lengths, are stored in buffers B11, B12 to detect oncoming of data signals with maximum delay in the respective transmission paths. The data are output simultaneously from the second buffer B2 to the respective transmission paths in a timing of the data having the maximum delay.

Abstract: A value of a current flowing through a specified spot of an optical module is detected by a current detector to be held in a memory. A value of a current is detected again by the current detector a predetermined time later, and a differential value between the detected value of the current and the value of the current held in the memory is obtained by an arithmetic circuit. An alarm circuit generates alarm signal when the differential value exceeds a predetermined threshold value, and calls an attention to a necessity of preventive maintenance. Alternatively, a ratio of the differential value to the past value is further obtained by the arithmetic circuit. The alarm circuit compares the obtained ratio with a predetermined threshold value. If the differential value or the ratio exceeds the predetermined threshold value, the alarm circuit generates the alarm signal.