Fujitsu Corporation

Fujitsu Microelectronics Limited

Akira Miho

Yukihiro Ozawa

Hideki Isobe

Tatsuya Akiyama

A semiconductor integrated circuit includes a bus, a CPU connected to the bus, a DAC having a digital input thereof connected to the bus, an ADC having a digital output thereof connected to the bus, a voltage generating circuit, a first switch configured to cause an electrical coupling between an analog input of the ADC and the voltage generating circuit to switch between a conductive state and a nonconductive state, and a second switch configured to cause an electrical coupling between an analog output of the DAC and the analog input of the ADC to switch between a conductive state and a nonconductive state.

Calculation of ADC and DAC errors in LSI chip

A semiconductor integrated circuit includes a reference-voltage circuit configured to produce a predetermined reference voltage at an output node thereof, a comparator, coupled to a node to which an oscillating signal is supplied and to the output node of the reference-voltage circuit, to produce a result of comparison at an output node thereof, the result of comparison being made by comparing a voltage of the oscillating signal with the predetermined reference voltage, and a detection circuit coupled to the output node of the comparator to produce, in response to the result of comparison, a stable-state-detection signal indicating that the oscillating signal has an amplitude larger than the reference voltage.

Semiconductor integrated circuit with function to detect state of stable oscillation

An semiconductor device includes a voltage-decreasing regulator which converts a source voltage into an output voltage in accordance with a control signal, the regulator supplying the output voltage to an internal module via a power line. An analog-to-digital converter converts the output voltage received from the power line, into an output signal indicating a value of the output voltage. A voltage monitoring circuit has a control register holding a value predetermined for a selected operational mode. The voltage monitoring circuit generates the control signal based on a result of comparison between the value indicated by the output signal of the converter and the value held by the control register, and outputs the control signal to the regulator so that the regulator supplies the output voltage, adjusted to an optimal output voltage for the selected operational mode by the control signal, to the internal module.

Semiconductor device including a voltage monitoring circuit

An analog-to-digital converter includes a sample and hold circuit for sampling and holding an analog input signal, a comparator circuit for comparing the analog input signal held by the sample and hold circuit with an input signal and generating an output signal, a control circuit for generating a digital signal based on the output signal of the comparator circuit, a digital-to-analog converter for converting the digital signal generated from the control circuit into an analog signal and for supplying the analog signal to the comparator circuit as the input signal, and an initial setting circuit for initializing the analog input signal held by the sample and hold circuit and the input signal which is output from the digital-to-analog converter to a reference voltage.

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Kawasaki, Japan

Akira Miho