Search results for "Wheatstone bridge"
showing 10 items of 20 documents
Coulomb blockade thermometer: Tests and instrumentation
1998
Coulomb blockade thermometry (CBT) provides a simple method for absolute thermometry in every day laboratory use at cryogenic temperatures. CBT has been found insensitive to even high magnetic fields. We review the principles and the operation of CBT and the fabrication of the sensors, and present new data on radiation hardness and stability of the sensors. We describe the instrumentation of CBT in detail. We have developed two signal conditioning units for CBT measurements. One is a modified alternating current resistance bridge, a versatile laboratory instrument operating with a PC computer, and the other one is a simple stand-alone instrument for direct temperature reading. Test results …
MgO Magnetic Tunnel Junction Electrical Current Sensor With Integrated Ru Thermal Sensor
2013
Full Wheatstone bridge electrical current sensor incorporating 114 MgO-based magnetic tunnel junction elements (3 × 30 μm2) connected in series was produced for improved electrical robustness. To that end, magnetic tunnel junctions with R × A ~7 KΩ μm2 tunneling magnetoresistance of 200%, were produced. The sensor was designed with an integrated Ru thin film resistive thermal detector (RTD) for temperature drift monitoring and compensation. In order to achieve a full bridge signal, a U-shaped copper trace was placed under a printed circuit board (PCB) specifically designed for this type of device. The resulting device exhibit sensitivities of 63.9 V/Oe/A in a 75 Oe linear range biased with …
Note: A non-invasive electronic measurement technique to measure the embedded four resistive elements in a Wheatstone bridge sensor
2015
The work shows a measurement technique to obtain the correct value of the four elements in a resistive Wheatstone bridge without the need to separate the physical connections existing between them. Two electronic solutions are presented, based on a source-and-measure unit and using discrete electronic components. The proposed technique brings the possibility to know the mismatching or the tolerance between the bridge resistive elements and then to pass or reject it in terms of its related common-mode rejection. Experimental results were taken in various Wheatstone resistive bridges (discrete and magnetoresistive integrated bridges) validating the proposed measurement technique specially whe…
Current-Based Measurement Technique for High Sensitivity Detection of Resistive Bridges With External Balancing Through Control Voltages
2017
We present a novel approach based on differential measurements of dc currents with very high sensitivity suitable for the detection of very small variations of resistors in Wheatstone full-bridge configurations. External control voltages allow for the compensation of the bridge unbalancing avoiding the need of changing its elements so making the solution suitable for integrated sensor systems. The proposed current-based measurement technique has been implemented through three different circuits, in transimpedance configuration and without the use of any further amplification stage, employing only two active blocks that allow for a very high integration level. The main characteristics of the…
Total ionizing dose (TID) evaluation of magnetic tunnel junction (MTJ) current sensors
2015
Abstract The paper shows an experimental study to know the behaviour of tunnel magnetoresistive effect-based current sensors configured in a Wheatstone bridge in response to irradiation. In particular the sensitivity, hysteresis, output offset voltage and input resistance are discussed when the sensors are submitted to a total irradiation dose of 43 krad with 36 krad/h dose rate. The same electrical parameters were studied subsequently once the irradiated sensors were submitted to an 80 °C annealing process. The studied TMR sensors are applied in a switched-mode power converter for space application.
Electrical Characterization of a Magnetic Tunnel Junction Current Sensor for Industrial Applications
2012
The objective of the work was the design of a Wheatstone bridge current sensor using MTJ as magnetoresistive elements. Each one of the four resistances of the bridge consists on 360 MTJ single elements connected in series for improved electrical robustness. A printed circuit board (PCB) was designed with a U-shaped copper trace placed under the PCB maintaining a 1.1 mm separation distance between sensor and trace. A 160% of tunnel magnetoresistance effect in the single junction and a 120% in its corresponding series elements connection has been achieved with a sensitivity of 9.2 Ω/Oe in a 65 Oe linear range. The DC sensor sensitivity in response to an external DC current sweeps of ±10, ±20,…
An electrical current smart transducer based on PSoC platform and integrated spin-valve sensor with embedded thin film Ruthenium temperature sensor
2011
This work presents an intelligent electrical current sensor that combines a programmable system on chip (PSoC) with a microfabrication of a giant magnetoresistance sensor (GMR) and resistive temperature detector (RTD). Four spin-valve GMR elements configured in a Wheatstone bridge sense the electrical current, while a thin film RTD based on Ruthenium measures the temperature for spin-valve bridge sensitivity thermal compensation. The mixed signal PSoC allows implement in a single chip all electronic circuits needed to design a smart transducer: the spin-valve biasing, conditioning signal, analog to digital converter, digital signal processing and ports for communications. In the experimenta…
Power monitoring in dielectric-loaded plasmonic waveguides with internal Wheatstone bridges
2013
We report on monitoring the mode power in dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) by measuring the resistance of gold electrodes, supporting the DLSPPW mode propagation, with internal (on-chip) Wheatstone bridges. The investigated DLSPPW configuration consisted of 1-μm-thick and 10-μm-wide cycloaliphatic acrylate polymer ridges tapered laterally to a 1-μm-wide ridge placed on a 50-nm-thin and 4-um wide gold stripe, all supported by a ~1.7-µm-thick Cytop layer deposited on a Si wafer. The fabricated DLSPPW power monitors were characterized at telecom wavelengths, showing very high responsivities reaching up to ~6.4 μV/μW (for a bias voltage of 245 mV) and the operati…
GMR Based Sensors for IC Current Monitoring
2013
The Giant MagnetoResistance (GMR) effect is a magnetic coupling mechanism that can be obtained in multilayer structures of few nanometers thick. In these devices, and at room temperature, the resistance is a function of the external magnetic field, at optimal levels for being used as sensors. Since the GMR effect was reported, scientists and engineers have dedicated their effort to this topic. This way, after two decades, a a very good knowledge of the GMR underlying physics together with notable designs of GMR based devices are nowadays available. They were initially used in the read heads of hard drives, but the constant evolution that this technology has experienced has open new fields o…
The Measurement of Large Strains Using Electrical Resistance Strain Gages
2011
It is well known that in the range of large strains, the electrical resistance strain gages have a nonlinear behavior, that is the variation of electrical resistance is a nonlinear function of the strain applied to the strain gage, which means that the gage factor K is not constant. Also, the Wheatstone bridge has a nonlinear behavior at large strains. Usually the two nonlinearities have opposite effects, therefore the overall nonlinearity decreases. This article presents an overview of the behavior of strain gages subject to large strains and of the corrections to account for nonlinearities of both the strain gage and the Wheatstone bridge.