Abstract: A sensor circuit includes an AC component pickup circuit and first and second adder circuits or first and second high-pass filters, and specifies a range of normal voltages by an upper-limit voltage formed by adding an upper-limit threshold value to the AC component in the input voltage and by a lower-limit voltage formed by adding a lower-limit threshold value to the AC component in the input voltage. An abnormal offset voltage is detected by judging whether the output voltage of an inverting amplifier circuit is lying in the range of normal voltages.

Abstract: The capacitance type physical quantity sensor has a sensing part including a capacitor element generating a capacitance signal representing a magnitude of a physical quantity to be sensed, and a sensor circuit including a charge amplifier converting the capacitance signal into a voltage signal. The charge amplifier includes an operational amplifier applied with the capacitance signal at an inverting input terminal thereof and applied with a reference voltage at a non-inverting input terminal thereof, a first capacitor connected between the inverting input terminal and an output terminal of the operational amplifier, a feedback resistor connected in parallel to the first capacitor, and a switch connected in parallel to the first capacitor and configured to be closed to make a short circuit between the inverting input terminal and the output terminal upon receiving a refresh signal supplied from outside.

Abstract: In an anomaly detector that detects an abnormal condition of an oscillation signal of a circuit such as a vibratory sensing circuit, the oscillation signal, having AC and DC components, is converted to a pair of first and second signals of either opposite-polarity DC amplitudes or opposite-phase alternating amplitudes. The first and second signals are combined to cancel the AC component of the oscillation signal to detect the DC component. The DC component is then compared with the upper and lower thresholds of a decision range to produce an alarm if the DC component goes outside the decision range. In one embodiment, the first and second signals are produced by detecting positive and negative peak values of the oscillation signal at intervals. In a second embodiment, the first signal is produced by high-pass filtering the oscillation signal as a replica of the AC component and the second signal is the oscillation signal itself.

Abstract: A compact sense amplifier circuit for amplifying reading signal of an EPROM includes a bit line connected to cells of the EPROM and a transistor circuit for connecting a DC power source to the bit line. The transistor circuit includes a read circuit, a write circuit, a first path for passing current when a read signal for reading one of the cells that is not written is applied to the read circuit and a second path for passing current when a read signal for reading one of the cells that is written is applied to the read circuit. The first path and the second path are arranged to pass the same amount of current, thereby reducing sensor noises.

Abstract: The gyro sensor uses a clock signal as a timing signal or synchronous signal for reading various data stored in a built-in memory for its yaw rate sensing operation. The gyro sensor is configured to use, as such a clock signal, the self-excited oscillation signal being applied to the vibrator of the gyro sensor as a vibrator drive signal.

Abstract: A sensor circuit includes an AC component pickup circuit and first and second adder circuits or first and second high-pass filters, and specifies a range of normal voltages by an upper-limit voltage formed by adding an upper-limit threshold value to the AC component in the input voltage and by a lower-limit voltage formed by adding a lower-limit threshold value to the AC component in the input voltage. An abnormal offset voltage is detected by judging whether the output voltage of an inverting amplifier circuit is lying in the range of normal voltages.

Abstract: The capacitance type physical quantity sensor has a sensing part including a capacitor element generating a capacitance signal representing a magnitude of a physical quantity to be sensed, and a sensor circuit including a charge amplifier converting the capacitance signal into a voltage signal. The charge amplifier includes an operational amplifier applied with the capacitance signal at an inverting input terminal thereof and applied with a reference voltage at a non-inverting input terminal thereof, a first capacitor connected between the inverting input terminal and an output terminal of the operational amplifier, a feedback resistor connected in parallel to the first capacitor, and a switch connected in parallel to the first capacitor and configured to be closed to make a short circuit between the inverting input terminal and the output terminal upon receiving a refresh signal supplied from outside.

Abstract: The gyro sensor uses a clock signal as a timing signal or synchronous signal for reading various data stored in a built-in memory for its yaw rate sensing operation. The gyro sensor is configured to use, as such a clock signal, the self-excited oscillation signal being applied to the vibrator of the gyro sensor as a vibrator drive signal.

Abstract: In a charge amplifier, an operational amplifier is provided. The operational amplifier has an inverting input terminal, a non-inverting input terminal, and an output terminal. An adjustable feedback resistor element is provide to be connected between the inverting terminal and the output terminal. A resistance adjusting circuit is provided to be electrically connected to the adjustable feedback resistor element. The resistance adjusting circuit adjusts the resistance of the adjustable feedback resistor element to a first resistance during a first predetermined period after power-on. The resistance adjusting circuit also adjusts the resistance of the adjustable feedback resistor element to a second resistance after the first predetermined period has elapsed. The second resistance is higher than the first resistance.

Abstract: In an anomaly detector that detects an abnormal condition of an oscillation signal of a circuit such as a vibratory sensing circuit, the oscillation signal, having AC and DC components, is converted to a pair of first and second signals of either opposite-polarity DC amplitudes or opposite-phase alternating amplitudes. The first and second signals are combined to cancel the AC component of the oscillation signal to detect the DC component. The DC component is then compared with the upper and lower thresholds of a decision range to produce an alarm if the DC component goes outside the decision range. In one embodiment, the first and second signals are produced by detecting positive and negative peak values of the oscillation signal at intervals. In a second embodiment, the first signal is produced by high-pass filtering the oscillation signal as a replica of the AC component and the second signal is the oscillation signal itself.

Abstract: A compact sense amplifier circuit for amplifying reading signal of an EPROM includes a bit line connected to cells of the EPROM and a transistor circuit for connecting a DC power source to the bit line. The transistor circuit includes a read circuit, a write circuit, a first path for passing current when a read signal for reading one of the cells that is not written is applied to the read circuit and a second path for passing current when a read signal for reading one of the cells that is written is applied to the read circuit. The first path and the second path are arranged to pass the same amount of current, thereby reducing sensor noises.

Abstract: The present invention relates to a sensor apparatus capable of outputting an accurate sensor signal irrespective of a variation of power supply voltage. In the sensor apparatus, when an A/D conversion circuit produces and outputs digital data, a switch circuit is placed into a first switching condition so that a constant voltage is applied from a constant-voltage circuit to an oscillation circuit, and a stabilized oscillation frequency is outputted from the oscillation circuit to the A/D conversion circuit. Thus, even if a power supply voltage varies, the A/D conversion circuit carries out sampling processing on analog data on the basis of the stabilized oscillation frequency from the oscillation circuit to produce and output the digital data.

Abstract: The present invention relates to a sensor apparatus capable of outputting an accurate sensor signal irrespective of a variation of power supply voltage. In the sensor apparatus, when an A/D conversion circuit produces and outputs digital data, a switch circuit is placed into a first switching condition so that a constant voltage is applied from a constant-voltage circuit to an oscillation circuit, and a stabilized oscillation frequency is outputted from the oscillation circuit to the A/D conversion circuit. Thus, even if a power supply voltage varies, the A/D conversion circuit carries out sampling processing on analog data on the basis of the stabilized oscillation frequency from the oscillation circuit to produce and output the digital data.