A circuit includes a digital-to-analog conversion circuit, an amplifying circuit, a mixing circuit, and an analog-to-digital converter. The digital-to-analog conversion circuit is configured to receive and convert audio data in the digital domain and output audio data in the analog domain. The audio data includes a main-tone component. The amplifying circuit is configured to output an audio signal according to the audio data in the analog domain. The mixing circuit is configured to eliminate the main-tone component according to the audio data in the analog domain and the audio signal and to output a feedback signal. The analog-to-digital converter is configured to convert the feedback signal from the analog domain to the digital domain.

The carbon monoxide detector and shutoff system is an electrical switching device. The carbon monoxide detector and shutoff system inserts into an electrical connection between the national electric grid and an electrical load. The carbon monoxide detector and shutoff system senses the carbon monoxide concentration within the atmosphere. Should the detected concentration of carbon monoxide exceed a threshold level, the carbon monoxide detector and shutoff system interrupts the circuit between the national electric grid and the electrical load. The carbon monoxide detector and shutoff system comprises a pass-through circuit, a control circuit, and a housing. The housing contains the pass-through circuit and the control circuit. The pass-through circuit inserts a relay between the national electric grid and the electrical load. The control circuit is an electrical circuit that opens and closes the relay in response to the detected concentration of carbon monoxide.

A pseudo-resistor structure, comprises: a first and a second PMOS transistor or PN diode configured as two-terminal devices, wherein the positive terminal of the first PMOS transistor or PN diode is connected to the positive terminal of the second PMOS transistor or PN diode, and wherein the negative terminal of the first PMOS transistor or PN diode is connected to an input (A) of the pseudo-resistor structure and wherein the negative terminal of the second PMOS transistor or PN diode is connected to an output (C) of the pseudo-resistor structure, and a dummy transistor or dummy diode connected to the input (A), wherein the dummy transistor or dummy diode is further connected to a bias voltage for compensating a leakage current through the first and the second PMOS transistors or PN diodes. A closed-loop operational amplifier circuit comprising the pseudo-resistor structure is provided. Also, a bio-potential sensor comprising the closed-loop operational amplifier circuit is provided.

A preamplifier comprises an input stage and a capacitive coupling stage. The input stage is arranged to receive a differential signal from a magnetic resistor which indicates a magnetic field sensed on a magnetic disk of a hard disk drive (HDD) when the preamplifier is powered on from an off state. The capacitive coupling stage has an input arranged to receive the differential signal from the input stage, a filter comprising a first resistor, a second resistor, a first capacitor, a second capacitor, and switches arranged in parallel with respective resistors, where the switches are closed when the preamplifier is powered on from the off state to an on state. A switch control is arranged to determine that an offset of the differential signal has settled and open the switches based on the determination.

A semiconductor device includes a semiconductor chip having first, second and third pads, first and second external terminals to which a power supply potential or a reference potential is supplied, first and second wires connecting the first and second external terminals and the first and second pads, and a third wire connecting the second external terminal and the third pad. The semiconductor chip further includes a first internal wiring connected to the first and second pads, a second internal wiring connected to the third pad, and a detection circuit. The detection circuit includes: a current source for passing a current through the first and second internal wirings; first and second resistive elements connected between the current source and the first and second internal wirings; and an amplifier circuit for amplifying a relative potential difference generated between the first and second resistive elements and outputting a detection signal.

A difference amplifier can he used for providing an amplified representation of a sensed current through a load device. A separate signal path can be used to provide fast fault detection, without requiring use of the difference amplifier. For example, a voltage scaling circuit can be used to scale a differential input signal indicative of the load current. The scaled representation can then be compared against a specified threshold corresponding to a fault current value. In this manner, a high-speed low-voltage comparator can be used to provide detection of a fault current that otherwise exceeds an input range of the difference amplifier, where the difference amplifier is used separately for precision current monitoring. As an illustrative example, such a scheme can provide fault detection even when an input of the difference amplifier is saturated.

Techniques for shielding wearable surface electromyography (sEMG) devices are described. According to some aspects, an sEMG device may comprise amplification circuitry comprising at least a first differential amplifier and at least two sEMG electrodes electrically connected to the amplification circuitry. The device may further comprise at least one auxiliary conductor not electrically connected to the amplification circuitry, wherein the at least one auxiliary conductor is configured to be electrically coupled to a wearer of the wearable device, and an electromagnetic shield surrounding the wearable device at least in part and electrically connected to the at least one auxiliary conductor.

A preamplifier comprises an input stage and a capacitive coupling stage. The input stage is arranged to receive a differential signal from a magnetic resistor which indicates a magnetic field sensed on a magnetic disk of a hard disk drive (HDD) when the preamplifier is powered on from an off state. The capacitive coupling stage has an input arranged to receive the differential signal from the input stage, a filter comprising a first resistor, a second resistor, a first capacitor, a second capacitor, and switches arranged in parallel with respective resistors, where the switches are closed when the preamplifier is powered on from the off state to an on state. A switch control is arranged to determine that an offset of the differential signal has settled and open the switches based on the determination.

An analog discrete current mode negative feedback amplifier circuit for use with a micro-fused strain gauge is disclosed. The amplifier circuit includes a Wheatstone bridge coupled to a first power supply and a second power supply. The first power supply and the second power supply can be configured such that the periodically alternate between two voltage levels. The Wheatstone bridge can be coupled to a negative feedback amplifier circuit with common mode detection. The amplifier circuit can comprise a differential amplifier with a negative feedback configuration coupled to a common mode amplifier. In addition, the output of each of the amplifiers can be coupled to a common-mode amplifier. In a pressure sensing application, the output of the common mode amplifier serves to output the temperature while the differential amplifiers serve to output the pressure.

A semiconductor device includes a semiconductor chip having first, second and third pads, first and second external terminals to which a power supply potential or a reference potential is supplied, first and second wires connecting the first and second external terminals and the first and second pads, and a third wire connecting the second external terminal and the third pad. The semiconductor chip further includes a first internal wiring connected to the first and second pads, a second internal wiring connected to the third pad, and a detection circuit. The detection circuit includes: a current source for passing a current through the first and second internal wirings; first and second resistive elements connected between the current source and the first and second internal wirings; and an amplifier circuit for amplifying a relative potential difference generated between the first and second resistive elements and outputting a detection signal.