Abstract: A calculation unit calculates a detection value of a capacitance of a capacitor based on a detection signal. A correction unit repeatedly performs a shift to a correction mode. When the correction mode is entered, the correction unit controls an AC voltage output unit so that a difference between amplitudes of first and second AC voltages changes, and obtains a correction value corresponding to a change in the detection value of the calculation unit caused by the change in the difference between the amplitudes. The correction unit corrects the detection value calculated by the calculation unit in accordance with the change in the correction values obtained in the correction mode.

Abstract: A first detection signal creation unit has detection nodes connected to detection electrodes in one-to-one correspondence. The first detection signal creation unit supplies charge from each detection node through a second wire to the relevant detection electrode so that a voltage at the relevant detection node vibrates according to an alternating-current voltage, and creates first detection signals matching the supplied charge. First filters are provided in first paths, each of which branches from an alternating-current output node to a first wire. A phase difference signal creation unit creates a phase difference signal matching the phase difference between the alternating-current voltage and one of the first detection signals.

Abstract: A capacitance detection device has: a first capacitor disposed in the path between a first node connected to a detection electrode and a second node; a second capacitor disposed in the path between the first node and the ground; a third capacitor disposed in the path between the first node and a third node connected to a shield electrode placed in proximity to the detection electrode; an alternating-current voltage output circuit that outputs a first alternating-current voltage to the third node; a first attenuation circuit that outputs a second alternating-current voltage resulting from attenuating the amplitude of the first alternating-current voltage; and a charge amplifier that supplies charge to the first capacitor through the second node and outputs a detection signal matching the supplied charge.

Abstract: A sensor detects the rotation of a component (object) of a vehicle in a non-contact manner, and generates a differential signal according to the rotation. Two comparators have different hysteresis characteristics. At both edges of one signal that is an output of one of the comparators, if a signal of the other comparator is not at the same level, it is determined that a distance (gap) between an object and the sensor is within a predetermined range in which the differential signal is effective.

Abstract: A sensor detects the rotation of a component (object) of a vehicle in a non-contact manner, and generates a differential signal according to the rotation. Two comparators have different hysteresis characteristics. At both edges of one signal that is an output of one of the comparators, if a signal of the other comparator is not at the same level, it is determined that a distance (gap) between an object and the sensor is within a predetermined range in which the differential signal is effective.

Abstract: A protection circuit includes a power supply terminal, a ground terminal, a control unit connected to the power supply terminal and the ground terminal, and a supply unit connected to the power supply terminal and the ground terminal, for preventing application of voltage in a reverse direction to a circuit unit having a predetermined function. In this case, the control unit generates a control potential, which controls the control unit and the supply unit in accordance with a potential supplied from the power supply terminal and a potential supplied from the ground terminal. The supply unit is configured to be capable of supplying current to a circuit unit connected to a subsequent stage on the basis of a potential supplied from the power supply terminal, a potential supplied from the ground terminal, and the control potential generated by the control unit.

Abstract: Provided is a control method of a frequency variable filter circuit including a resonant circuit of an inductor and a variable capacitance unit, the method including: determining a center frequency of the frequency variable filter circuit, wherein the variable capacitance unit includes a capacitor bank, a capacitance value Y of the capacitor bank is expressed by an equation below with respect to an assigned frequency, and the center frequency thereof is determined by deciding coefficients ?, ?, A, B and C. Y=A×(??X)n+B×(??X)(n-1)+C×(??X)(n-2)+ . . .

Abstract: A wideband amplifying circuit includes a first bipolar transistor in which an RF signal is input at an input terminal, a transistor output circuit connected to a collector of the first bipolar transistor, and a feedback circuit connected between the output terminal of the transistor output circuit and a base of the first bipolar transistor. The feedback circuit is formed by a series-connected circuit of a first resistor in which one terminal is connected to the input terminal of the first bipolar transistor, and a second resistor in which one terminal is connected to the output terminal of the transistor output circuit and the other terminal is connected to the other terminal of the first resistor, and a third resistor is provided between a connection point of the first resistor and the second resistor and the ground.

Abstract: A splitter circuit includes a plurality of transistors each including a collector that is connected to a direct-current power supply and a base to which a common input signal is supplied, and a plurality of first resistors each including one end that is grounded and the other end that is connected to an emitter of a corresponding one of the plurality of transistors. A signal that appears on the emitter of each of the plurality of transistors is output from the other end of a corresponding one of the plurality of first resistors as an output signal.

Abstract: An FM demodulator for reproducing data by performing FM demodulation of a received RF signal in a Bluetooth transmission system is provided. The FM demodulator includes a frequency discrimination unit and a level determination unit. The FM demodulator frequency-discriminates the RF signal, performs digital conversion of the discriminated RF signal, and outputs converted data. The level determination unit performs level comparison of current input-data, supplied from the frequency discrimination unit in the latest clock period, with last input-data, supplied from the frequency discrimination unit in the immediately preceding clock period, determines a logic state of the current input-data based on the result of the level comparison, and reproduces data in accordance with the determined logic state.

Abstract: An FM demodulator for reproducing data by performing FM demodulation of a received RF signal in a Bluetooth transmission system is provided. The FM demodulator includes a frequency discrimination unit and a level determination unit. The FM demodulator frequency-discriminates the RF signal, performs digital conversion of the discriminated RF signal, and outputs converted data. The level determination unit performs level comparison of current input-data, supplied from the frequency discrimination unit in the latest clock period, with last input-data, supplied from the frequency discrimination unit in the immediately preceding clock period, determines a logic state of the current input-data based on the result of the level comparison, and reproduces data in accordance with the determined logic state.