A method and apparatus for calibrating an impedance measurement device (100a, 100b, 100c) are provided. The impedance measurement device outputs (502) a first AC signal to a phase-locked current generator (124). The phase-locked current generator generates (504) 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 (506) 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 (508) based on the measured impedance value and the known impedance value of the presented impedance.

A pre-characterised high frequency signal (14) is provided by means of a non-linear circuit, for example an amplifier circuit (10), fed with a first signal (12) with a component at a first, fundamental, frequency (FO). The amplifier circuit generates an output signal comprising harmonic components (14.sub.h1, 14.sub.h2, 14.sub.h3) having stable and predetermined phase relation relative to each other. Information concerning the phase relation of the harmonic frequency components is provided, for example by means of a data file (16). At least two of the harmonic components are at the tenth or lower harmonic frequencies. The signal strength of such low-order harmonic components may be relative high, thus enabling the provision of a pre-characterised high frequency multi-tone signal from the amplifier circuit with high signal to noise ratio.

Disclosed herein is a detector that detects precision in charging current of a battery cell charging and discharging device, the detector including an instrument unit and a power supply unit, wherein the instrument unit includes a housing formed in a box shape open at a top thereof and a plurality of voltage measurement parts including a pair of connection terminals mounted at opposite sides of the housing inside the housing to detect precision in current of the charging and discharging device, the connection terminals being electrically connected to the power supply unit, and shunt resistance parts to apply uniform resistance to the respective connection terminals, and the power supply unit includes a charging and discharging device to supply current to the voltage measurement parts and to charge and discharge a battery cell and a multi-meter to measure current and voltage of the shunt resistance parts.

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 for testing a sensor within an electronic circuit. The sensor includes a first sensor element and a first reference element in a first branch, and a second sensor element and a second reference element in a second branch of the Wheatstone bridge circuit, which is in parallel with the first branch. The Wheatstone bridge circuit includes first and second inputs for first and second reference signals, respectively, which are each connected to the branches. The first branch includes a first signal output, and the second branch includes a second signal output between the second sensor element and the second reference element. The method includes: opening the first or second switch; applying a predefined first and/or second reference signal(s); and evaluating a first or second useful signal as to whether damage to the sensor or an electrical connection between the sensor and the electronic circuit exists.

In a system for testing antenna performance, antenna performance is tested by reflecting the loss of a cable used in the antenna performance test. The system for testing antenna performance includes a tester having a test port, the test port being connected, via a cable, to an antenna that communicates with a terminal to be tested, in a shield box, when a test mode is set, wherein the tester outputs a test signal to the test port, receives a response signal corresponding to the test signal via the test port, and obtains a value, as a communication performance measurement value, by adding a calibration value to a reception signal strength of the response signal.

A continuous, always on, high accuracy AC reference signal is added to an AC voltage of interest to calibrate the AC voltage of interest. The AC reference voltage has a first frequency. The AC voltage of interest has a second frequency. A control system having calibration.

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 system and method sequentially measure phases of selected comb teeth of a comb signal using a local oscillator (LO) signal whose frequency and phase are changed for each sequential measurement, and adjust the measured phases to account for the change of phase in the LO signal from measurement of one selected comb tooth to the next to ascertain reference phase differences between the selected comb teeth. The measured phases of the selected comb teeth are adjusted by applying a phase offset determined from a first phase and a second phase of a pilot tone which are measured using the LO signal, respectively, before and after the frequency and phase of the LO signal change from measurement of one comb tooth to the next. The frequency of the pilot tone is maintained to be substantially the same when measuring the first phase and the second phase of the pilot tone.

To determine whether the current temperature of a probe assembly is stable for the calibration at the auxiliary site, a wafer probe station verifies a measured air standard dataset with a predetermined signal range or verifying an estimated measurement time range with a predetermined time window. To determine whether adjusting the current temperature of a probe assembly at the wafer site is necessary, a wafer probe station verifies a measured air standard dataset with a predetermined signal range or verifying an estimated measurement time range with a predetermined time window. To determine whether the current temperature of a probe assembly is ready for testing a semiconductor device, a wafer probe station verifies a measured air standard dataset with a predetermined signal range.