In an example method of trimming a voltage reference circuit, the method includes: setting the circuit to a first temperature; trimming a first resistor (R.sub.DEGEN) of a differential amplifier stage of the circuit; and trimming a first resistor (R1) of a scaling amplifier stage of the circuit. The trimming equalizes current flow through the differential amplifier stage and the scaling amplifier stage. The method includes: trimming a second resistor (R2) of the scaling amplifier stage to set an output voltage of the circuit to a target voltage at the first temperature; setting the circuit to a second temperature; and trimming a second resistor (R.sub.PTAT) of the differential amplifier stage, a third resistor (R1.sub.PTAT) of the scaling amplifier stage, and a fourth resistor (R2.sub.PTAT) of the scaling amplifier stage to set the output voltage of the circuit to the target voltage at the second temperature.

A leakage current detection device includes a self-test unit for activating a simulated leakage current signal; a leakage current detection unit for detecting the simulated leakage current signal and the actual leakage current signal, where when at least one of them is present, the leakage current detection unit activates a trigger signal, and when both of them are absent, the leakage current detection unit deactivates the trigger signal; a self-test feedback turnoff unit for detecting the trigger signal, where when the trigger signal is detected, the self-test feedback turnoff unit deactivates the simulated leakage current signal before a predetermined time point; and a power line disconnect unit for detecting the trigger signal after the predetermined time point, and when the trigger signal is detected, it disconnects the power between the power source and the load.

A Josephson voltage standard includes: electrical conductors that receive bias currents and radiofrequency biases; a first Josephson junction array that: includes a first Josephson junction and produces a first voltage reference from the first bias current and the third bias current; a second Josephson junction array in electrical communication with the first Josephson junction array and that: includes a second Josephson junction; receives the second bias current; receives the third bias current; receives the second radiofrequency bias; and produces a second voltage reference from the second bias current and the third bias current; a first voltage reference output tap in electrical communication with the first Josephson junction array and that receives the first voltage reference from the first Josephson junction array such that the first voltage reference is electrically available at the first voltage reference output tap; and a second voltage reference output tap.

An apparatus comprises a signal generator; first and second electrodes, the second electrode being connected to a first terminal of the signal generator; a processor; and a first switch configured to connect the first electrode to the processor, the first switch having a first position and a second position. The processor is configured to determine one or more values of a first electrical parameter based on a signal received from the first electrode via the first switch in the first position, and to determine one or more values of a second electrical parameter based on a signal received from the first electrode via the first switch in the second position.

Systems and methods for measurement and management are disclosed that provide complex measurements cost-effectively at very high accuracy. These methods and systems in some cases achieve measurement accuracy exceeding the accuracy of the reference standards they rely on, and eliminate expensive and disadvantageous recalibration procedures. The accurate measurements are integrated with management functions, applying the measurement data to meet objectives of the integrated system and workflow goals of its user. The disclosed systems and methods comprise an explicit or expressly represented model both of themselves and of candidate external systems to be measured and managed. The models may be configured and reconfigured by the owner-user through either local or remote means. The system intelligently reconfigures itself to adapt dynamically to the conditions of measurement and the user's and system's goals at each moment. In an embodiment, the system includes high-accuracy and reconfigurable components including a meter or control head adapted for user precision assembly and maintenance that computes and displays or communicates the measurements, displaying measurements in desired units, grouping functions according to ergonomic and cognitive principles based on the activity and workflow of a user in relation to the internal model. The use of models permits the system to compute and provide complex and inferred measurements of ultimate interest to the user, including quantities that cannot be directed measured and only can be determined through reasoning or computation by applying models to raw measurement data. The precision-assembly modular electromechanical design further permits an owner-user to precisely assemble, maintain, modify the apparatus and calibrate the equipment for accuracy.

A calibration apparatus calibrates cross-frequency phases of large-signal network analyzer measurements and includes: a signal generator; a vector network analyzer that includes couplers and receivers that receive the calibration signal and the reference multitone signal from the signal generator; a calibration receiver that receives a calibration signal from the vector network analyzer and produces a digitized calibration temporal signal from the calibration signal; and a signal processor in communication with the signal generator and the vector network analyzer and that: receives the reference digitized signal from the reference receiver; receives the forward digitized signal from the forward coupled receiver; receives the reverse digitized signal from the reverse coupled receiver; receives the digitized calibration temporal signal from the calibration receiver; and produces a calibration factor from the reference digitized signal, the forward digitized signal, the reverse digitized signal, and the digitized calibration temporal signal.

A method and apparatus for calibrating an impedance measurement device are provided. The impedance measurement device outputs a first AC signal to a phase-locked current generator. The phase-locked current generator generates a second AC signal having a phase that is locked to a phase of the first AC signal and having an amplitude that is representative of a presented impedance having a known impedance value. The phase-locked current generator outputs the second AC signal to the impedance measurement device. The impedance measurement device performs an impedance measurement based on the second AC signal to produce a measured impedance value associated with the presented impedance. The impedance measurement device is calibrated based on the measured impedance value and the known impedance value of the presented impedance.

In described examples, a circuit includes a current mirror circuit. A first stage is coupled to the current mirror circuit. A second stage is coupled to the current mirror circuit and to the first stage. A voltage divider network is coupled to the second stage. The circuit includes an output transistor having first and second terminals, in which the first terminal of the output transistor is coupled to the first stage, and the second terminal of the output transistor is coupled to the voltage divider network.

A method and apparatus are for monitoring a secondary power device and for accurately checking a state of the secondary power device, and an electronic system includes the apparatus. The method of monitoring a secondary power device includes setting a first reference parameter by using a voltage of at least one capacitor of the secondary power device, setting a second reference parameter by using the voltage of the at least one capacitor and the first reference parameter, and setting a reference level for checking of the state of the secondary power device by using the second reference parameter, wherein the reference level is used in checking of the state of the secondary power device.

In an example method of trimming a voltage reference circuit, the method includes: setting the circuit to a first temperature; trimming a first resistor (R.sub.DEGEN) of a differential amplifier stage of the circuit; and trimming a first resistor (R1) of a scaling amplifier stage of the circuit. The trimming equalizes current flow through the differential amplifier stage and the scaling amplifier stage. The method includes: trimming a second resistor (R2) of the scaling amplifier stage to set an output voltage of the circuit to a target voltage at the first temperature; setting the circuit to a second temperature; and trimming a second resistor (R.sub.PTAT) of the differential amplifier stage, a third resistor (R1.sub.PTAT) of the scaling amplifier stage, and a fourth resistor (R2.sub.PTAT) of the scaling amplifier stage to set the output voltage of the circuit to the target voltage at the second temperature.