A calibration device for a network analyzer with several ports provides a calibration circuit, which is connected in each case via a terminal port respectively to one of the several ports of the network analyzer. A first transistor and a second transistor are connected in series to each terminal port. In this context, both transistors are connected by their common connection to the terminal port. The first transistor and/or the second transistor is operated as an adjustable load.

A method for operating an inductive conductivity sensor, wherein a first electric transmitter signal having a first signal frequency is generated and supplied to the transmitter coil, a first electric receiver signal is measured at the receiver coil and a first conductivity of the medium determined from the first electric receiver and first electric transmitter signals using a first calibration model. At least one further electric transmitter signal having a different signal frequency is generated and supplied to the transmitter coil, a further electric receiver signal is measured at the receiver coil and a further conductivity of the medium determined from the further electric receiver and electric transmitter signals using another calibration model, at least one conductivity difference is determined between each of the determined conductivities of the medium and when the at least one conductivity difference exceeds a threshold conductivity difference, the conductivity difference is signaled as an error.

A measurement system and a method of removing effects of instability of the measurement system while measuring at least one S-parameter of a device under test (DUT) are provided. The method includes initially determining a characteristic of the measurement system, including identifying a location of an instability in the time domain of the measurement system; determining a change of the characteristic of the measurement system while connected to the DUT; and compensating for the determined change of the characteristic of the measurement system while connected to the DUT by removing effects of the determined change on measurements of the at least one S-parameter of the DUT.

Self-testing proximity testing systems and corresponding methods are discussed herein and can include a proximity probe and controller in electrical communication via a cable. A self-testing subsystem can be in communication with the controller and configured to determine whether proximity probes and cables assembled with a controller are compatible or incompatible. The self-testing subsystem can place a known impedance in electrical communication with the controller, modifying a proximity signal output by the controller. When the modified proximity signal differs from a predicted proximity signal by greater than or equal to a threshold amount, the self-testing subsystem can output a first indication indicating that incompatible proximity probes and cables are assembled with a controller. When the modified proximity signal differs from a predicted proximity signal by less than the threshold amount, the self-testing subsystem can output a second indication indicating that compatible proximity probes and cables are assembled with a controller.

The present invention discloses an AC impedance measurement circuit with a calibration function, which is characterized in that only one calibration impedance is needed, associated with a switch circuit. Based on the measurement results of the two calibration modes, an equivalent impedance of the switch circuit, circuit gain and phase offset can be calculated. Based on the above results, the equivalent impedance of the internal circuit is deducted from the measurement result of the measurement mode to accurately calculate an AC conductance and a phase of the AC conductance for impedance to be measured. In addition, by adjusting a phase difference between an input sine wave signal and a sampling clock signal, impedance of the same phase and impedance of the quadrature phase can be obtained, respectively, and the AC impedance and phase angle of the impedance to be measured can be calculated.

A setting of a measurement instrument comprises the providing a reference measurement instrument that uses at least one instrument parameter. A training phase is performed for a particular signal type to be processed by said reference measurement instrument in order to retrieve an optimal setting for said at least one instrument parameter. A lookup table is created for said particular signal type, said lookup table comprising at least said optimal setting for said at least one instrument parameter.

A calibration method includes (a) connecting a impedance measuring device to an impedance standard which has at least two excitation terminals for feeding an excitation signal and two measuring terminals for determining a measurement signal, and which has a fixed or adjustable impedance which corresponds to the impedance target; (b) applying a voltage signal to the excitation terminals and measuring the current flowing through the impedance standard due to the voltage signal at the measuring terminals; or supplying a current signal to the excitation terminals and measuring the dropping voltage at the measuring terminals; and (c) calibrating the impedance measuring device against the impedance standard to the impedance target. The geometrical arrangement of terminals of the impedance standard corresponds to the geometrical arrangement of the terminals of the cell of which the impedance is to be measured.

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.

A measuring method according to an exemplary embodiment includes acquiring a temperature by a temperature sensor at a first time, and acquiring a first parameter that sets an admittance of a phase adjustment circuit. The measuring method includes acquiring a second parameter corresponding to the temperature acquired at the first time. The second parameter is generated based on a second parameter group that is pre-stored. The measuring method includes acquiring a correction parameter group by correcting a second parameter group to correspond to the first parameter based on the first parameter and the second parameter.

A quantum Hall resistance apparatus is to improve resistance standards and includes a substrate, a graphene epitaxially grown on the substrate and having a plurality of first contact patterns at edges of the graphene, a plurality of contacts, each including a second contact pattern and configured to connect to a corresponding first contact pattern, and a protective layer configured to protect the graphene and to increase adherence between the first contact patterns and the second contact patterns. The contacts become a superconductor at a temperature lower than or equal to a predetermined temperature and under up to a predetermined magnetic flux density.