Precision AC and DC voltage, current, phase, power and energy measurements and calibrations with current ranges from 1 uA to 20 kA and voltage ranges from 1V to 1000 kV are now performed with accuracies of better than one part per million. Continued demand for improved accuracy has led the inventors to address remnant magetization within the current comparators that form the basis of the measuring process within many of the measurement instruments providing the precision AC and DC measurements and calibrations. Accordingly, the inventors present current comparator and measurement system architectures together with control protocols to provide for correction of this remnant magnetization.

In one embodiment, a TMR field sensor utilizes existing one or more self-test current lines in a configuration to extend magnetic field measurement range without sacrificing measurement sensitivity. The self-test current lines are energized to facilitate magnetic field measurement when the measured magnetic field reaches a threshold. The magnetic field created by self-test coil opposes an external magnetic field being measured to keep the net magnetic field within a desired range where the magnetic field sensor has linear output and desired sensitivity.

Sensor devices disclosed herein allow multiple analytes or organisms to be individually tagged and selectively detected. When a binding event occurs one or more nanoswitches close and the corresponding array resistance value produces a voltage imbalance in the Wheatstone Bridge. The voltage detected by the voltage meter will then exhibit unique value change corresponding to the particular nanoswitche(s) in the array that are closed due to a binding event. Similarly the same functionalization chemistry can be used on all nanoswitches so that the voltage detected by the voltage meter corresponds to concentration levels of the target analyte. Multiple functionalization chemistries on each switch can also be used to improve selectivity for more complex analytes. In some disclosed embodiments, the Wheatstone bridge voltage is tied to a predetermined resistance change rather than to smaller resistance changes that would occur from functionalization of one leg of a nanowire Wheatstone bridge.

A measurement bridge circuit includes a first branch and a second branch. The first branch contains a first resistor which is sensitive to measured variables and an invariable resistor connected in series. A first tap point is located between the first resistor and the invariable resistor. The second branch contains a second resistor which is sensitive to measured variables and a variable resistor arrangement connected in series. The variable resistor arrangement includes a first component having an invariable electrical resistance value and a second component having a variable electrical resistance value. The second component is connected in parallel with the first component in order to vary a total electrical resistance value for the variable resistor arrangement. A second tap point is located between the second resistor and the variable resistor arrangement.

A measurement bridge circuit includes a first branch and a second branch. The first branch contains a first resistor which is sensitive to measured variables and an invariable resistor connected in series. A first tap point is located between the first resistor and the invariable resistor. The second branch contains a second resistor which is sensitive to measured variables and a variable resistor arrangement connected in series. The variable resistor arrangement includes a first component having an invariable electrical resistance value and a second component having a variable electrical resistance value. The second component is connected in parallel with the first component in order to vary a total electrical resistance value for the variable resistor arrangement. A second tap point is located between the second resistor and the variable resistor arrangement.

A sensor system with performance compensation testing capability includes a sensor device, a resistance bridge, a signal conditioning circuit, a first test connector, and a second test connector. The resistance bridge circuit is disposed on the sensor device and includes an excitation terminal, a circuit common terminal, and two output terminals, and is configured, upon being energized, to supply a bridge output voltage across the two output terminals. The signal conditioning circuit is electrically coupled to the excitation terminal, the circuit common terminal, and the two output terminals, and is configured to supply a sensor output signal representative of bridge output voltage. The first test connector is electrically coupled to one of the two output terminals and is configured to be coupled to an impedance test device. The second test connector is electrically coupled to the circuit common terminal and is configured to be coupled to the impedance test device.

A monitoring method is adapted for a circuit board. The circuit board includes a board body, a main circuit, and a standby circuit. The main circuit is located on the board body. The standby circuit is located on the board body, and is electrically connected to the main circuit. The standby circuit includes a first pressure detection circuit and a control circuit. The first pressure detection circuit is located at an area being monitored of the board body, and the control circuit outputs a first signal or a second signal according to a first detection value and a first predetermined range of the first pressure detection circuit.

Example embodiments relate to sensor readout systems and sensor readout methods. One example sensor readout system includes a signal generator configured to generate a biasing signal. The sensor readout system also includes a first chopper configured to modulate the biasing signal using a chopping signal with a chopping frequency f.sub.chop to generate a modulated biasing signal. Additionally, the sensor readout system includes a Wheatstone bridge circuit that includes resistive branches. At least one of the resistive branches includes an impedance-based sensor. The Wheatstone bridge circuit is configured to receive the modulated biasing signal and to generate a sensing signal based on the modulated biasing signal. Further, the sensor readout system includes a second chopper configured to modulate the sensing signal using the chopping signal with the chopping frequency f.sub.chop to generate a modulated sensing signal.