Abstract: A signal output device is provided in a communication apparatus. The communication apparatus communicates with a different one of the communication apparatus using a single line. The signal output device includes a signal output unit. The signal output unit includes a first filter and a second filter. The first filter is provided by a Bessel filter. The second filter is provided by a Chebyshev filter or a Butterworth filter. The signal output unit outputs a signal which is obtained by passing a predetermined signal through the first filter and the second filter. The signal output from the signal output unit has a pass characteristic of the first filter and a pass characteristic of the second filter. A cutoff frequency of the first filter is set to be lower than a cutoff frequency of the second filter.

Abstract: A signal output device is provided in a communication apparatus. The communication apparatus communicates with a different one of the communication apparatus using a single line. The signal output device includes a signal output unit. The signal output unit includes a first filter and a second filter. The first filter is provided by a Bessel filter. The second filter is provided by a Chebyshev filter or a Butterworth filter. The signal output unit outputs a signal which is obtained by passing a predetermined signal through the first filter and the second filter. The signal output from the signal output unit has a pass characteristic of the first filter and a pass characteristic of the second filter. A cutoff frequency of the first filter is set to be lower than a cutoff frequency of the second filter.

Abstract: A receiving device includes a receiving circuit and an impedance control circuit. The receiving circuit receives a signal transmitted through a communication line. The impedance control circuit is coupled with the receiving circuit and has a detecting part. The detecting part detects a physical value of the signal and the physical value includes at least one of a voltage, an electric current, and an electric power. The impedance control circuit changes an input impedance based on the detected value so that a ringing of the signal is reduced.

Abstract: In a transmission device for differential communication, a first cathode-side element part is coupled between a first communication line and a cathode-side power supply line, a second cathode-side element part is coupled between a second communication line and the cathode-side power supply line, a first anode-side element part is coupled between the first communication line and an anode-side power supply line, and a second anode-side element part is coupled between the second communication line and the anode-side power supply line. A driving portion drives the element parts based on transmission data input from an outside. A target potential generating portion generates target potentials of the element parts based on potentials of the first communication line and the second communication line.

Abstract: A signal transmission circuit is capable of reducing distortion that occurs during signal transmission. A digital output signal is transmitted from a terminal to a signal line via an output buffer circuit and an output impedance unit. The terminal is connected to an impedance variation unit via an impedance control unit. The impedance variation unit designates an impedance for terminating the signal line when the output data is changed from a high level H to a low level. A reflection occurring on the signal line can be prevented and a waveform distortion can be suppressed.

Abstract: A signal receiver includes: a receiving circuit that receives a differential signal via a transmission line, which includes a pair of signal wires for transmitting the differential signal; and an impedance control circuit that controls an input impedance so as to reduce a common mode noise. The impedance control circuit includes a detection element for detecting at least one of a voltage, a current and an electric power of the common mode noise. The impedance control circuit controls the input impedance in accordance with change of the at least one of the voltages the current and the electric power of the common mode noise.

Abstract: A transmission apparatus for differential communication includes a driver bridge circuit and a pair of noise protection circuits. The driver bridge circuit includes four output devices that are independently connected between each of a pair of transmission lines and a power line or a ground line. Each noise protection circuit is provided to a corresponding transmission lines. Each noise protection circuit includes a ground potential detector and an impedance controller. The ground potential detector detects a potential of the corresponding transmission line with respect to the ground line. The impedance controller causes an impedance of the corresponding transmission line with respect to the ground line to become equal to an impedance of the other transmission line with respect to the ground line, when the detected potential becomes outside a predetermined potential range.

Abstract: In a transmission device for differential communication, a first cathode-side element part is coupled between a first communication line and a cathode-side power supply line, a second cathode-side element part is coupled between a second communication line and the cathode-side power supply line, a first anode-side element part is coupled between the first communication line and an anode-side power supply line, and a second anode-side element part is coupled between the second communication line and the anode-side power supply line. A driving portion drives the element parts based on transmission data input from an outside. A target potential generating portion generates target potentials of the element parts based on potentials of the first communication line and the second communication line.

Abstract: A transmission apparatus for differential communication includes a driver bridge circuit and a pair of noise protection circuits. The driver bridge circuit includes four output devices that are independently connected between each of a pair of transmission lines and a power line or a ground line. Each noise protection circuit is provided to a corresponding transmission lines. Each noise protection circuit includes a ground potential detector and an impedance controller. The ground potential detector detects a potential of the corresponding transmission line with respect to the ground line. The impedance controller causes an impedance of the corresponding transmission line with respect to the ground line to become equal to an impedance of the other transmission line with respect to the ground line, when the detected potential becomes outside a predetermined potential range.

Abstract: A receiving device includes a receiving circuit and an impedance control circuit. The receiving circuit receives a signal transmitted through a communication line. The impedance control circuit is coupled with the receiving circuit and has a detecting part. The detecting part detects a physical value of the signal and the physical value includes at least one of a voltage, an electric current, and an electric power. The impedance control circuit changes an input impedance based on the detected value so that a ringing of the signal is reduced.

Abstract: A bus switch for connecting and disconnecting a bus connection provided by a pair of buses includes a first switching element and a second switching element. The first switching element is coupled between an input terminal and an output terminal of a high-potential side bus of the pair of buses. The second switching element is coupled between an input terminal and an output terminal of a low-potential side bus of the pair of buses. The bus connection is connected when the first switching element and the second switching element are activated, and the bus connection is disconnected when the first switching element and the second switching element are deactivated.

Abstract: A signal receiver includes: a receiving circuit that receives a differential signal via a transmission line, which includes a pair of signal wires for transmitting the differential signal; and an impedance control circuit that controls an input impedance so as to reduce a common mode noise. The impedance control circuit includes a detection element for detecting at least one of a voltage, a current and an electric power of the common mode noise. The impedance control circuit controls the input impedance in accordance with change of the at least one of the voltages the current and the electric power of the common mode noise.

Abstract: A signal transmission circuit is capable of reducing distortion that occurs during signal transmission. A digital output signal is transmitted from a terminal to a signal line via an output buffer circuit and an output impedance unit. The terminal is connected to an impedance variation unit via an impedance control unit. The impedance variation unit designates an impedance for terminating the signal line when the output data is changed from a high level H to a low level. A reflection occurring on the signal line can be prevented and a waveform distortion can be suppressed.

Abstract: An output circuit includes a constant current circuit that generates and supplies a constant current to an output terminal of the output circuit. Based on the constant current, the output circuit converts an input signal to an output signal having a voltage within a voltage range specified by upper and lower clamp voltages. The output signal is feedback to the constant current circuit. The constant current circuit changes the amount of the constant current in accordance with the output signal in such a manner that the constant current increases with an increase in the output signal and becomes zero when the output signal decreases to or below a threshold voltage. Thus, the upper clamp voltage is made as close to a power supply voltage as possible and the lower clamp voltage is made as close to a ground voltage as possible.

Abstract: A bus switch for connecting and disconnecting a bus connection provided by a pair of buses includes a first switching element and a second switching element. The first switching element is coupled between an input terminal and an output terminal of a high-potential side bus of the pair of buses. The second switching element is coupled between an input terminal and an output terminal of a low-potential side bus of the pair of buses. The bus connection is connected when the first switching element and the second switching element are activated, and the bus connection is disconnected when the first switching element and the second switching element are deactivated.

Abstract: An analog switch used in a switched capacitor filter has N-channel and P-channel MOS FETs connected in parallel between input and output switch terminals, with capacitor charge currents being periodically produced from the output terminal. The filter derives an output signal with respect to a reference voltage and maintains the switch input and output terminal at the reference voltage, while respective substrate potentials of the N-channel and P-channel MOS FETs are fixed at the reference voltage, so that the analog switch does not produce an external flow of leakage current that can affect the output signal of the filter during each interval when the switch is open.

Abstract: An output circuit includes a constant current circuit that generates and supplies a constant current to an output terminal of the output circuit. Based on the constant current, the output circuit converts an input signal to an output signal having a voltage within a voltage range specified by upper and lower clamp voltages. The output signal is feedback to the constant current circuit. The constant current circuit changes the amount of the constant current in accordance with the output signal in such a manner that the constant current increases with an increase in the output signal and becomes zero when the output signal decreases to or below a threshold voltage. Thus, the upper clamp voltage is made as close to a power supply voltage as possible and the lower clamp voltage is made as close to a ground voltage as possible.

Abstract: When a voltage applied to an output terminal exceeds a power source voltage to be supplied during an ordinary operation state, a reset signal turns into L level and the operation mode of a sensor goes into a trimming operation mode. The voltage entered into the output terminal is changed in a voltage range higher that the power source voltage to input trimming data with a data signal having L or H level. The entered trimming data is temporarily held by a latch and then written into a memory in response to a write voltage applied to a power source terminal in a write mode. Then, the trimming data held by the latch or the trimming data stored in the memory can be read out as a change in the sink current of the output terminal when a read mode is set.

Abstract: In a disconnection detecting circuit comprising a control circuit and a sensor circuit, an energizing current is supplied from the control circuit side through an output terminal to the sensor circuit side by energizing a transistor in the sensor circuit side directly in a state where a pull-up resistor or a pull-down resistor having a several k? to several tens k? is provided in the control circuit side. In addition, a current control circuit, a constant-current circuit, a bias circuit and a transistor unit are provided in the sensor circuit side so that, at the occurrence of a disconnection of a power supply line, the impedance of the sensor circuit side is set to be higher by at least one-digit than the resistance value of the pull-up resistor in the control circuit side. This enables detecting a disconnection of connection lines between circuits while preventing an increase in contact resistance of terminal contacts to the utmost.

Abstract: An analog switch used in a switched capacitor filter has N-channel and P-channel MOS FETs connected in parallel between input and output switch terminals, with capacitor charge currents being periodically produced from the output terminal. The filter derives an output signal with respect to a reference voltage and maintains the switch input and output terminal at the reference voltage, while respective substrate potentials of the N-channel and P-channel MOS FETs are fixed at the reference voltage, so that the analog switch does not produce an external flow of leakage current that can affect the output signal of the filter during each interval when the switch is open.