Voltage Differential Signaling Research Articles

Dual-range TMR current sensor based on magnetic shunt/aggregation effects utilizing single magnetic ring structure

In this paper, we propose and design a novel dual-range tunnel magnetoresistance (TMR) current sensor with a single magnetic ring structure. This design incorporates two distinct magnetic guiding effects, namely magnetic shunt and magnetic aggregation, within the same magnetic ring. By integrating a high-sensitivity TMR sensor chip with a closed-loop feedback circuit, we achieve a TMR current sensor with excellent linearity, high resolution, as well as high frequency response. The magnetic ring structure is first modeled and simulated, establishing a correlation between the distribution of magnetic induction intensity and the parameters of the magnetic ring and feedback coils. Through simulation optimization and theoretical calculations, we determine the optimal positions for TMR sensor chips in the magnetic ring, suitable for both current ranges. When a signal current is present, the TMR sensor chip generates a weak differential voltage signal, which is subsequently amplified, processed, and automatically transmitted to the laptop via a serial port. Furthermore, the sensor allows for automatic switching between the two current ranges. The results demonstrate that our designed dual-range current sensor exhibits outstanding performance characteristics, including a high resolution of 500 μA in the small range, accuracy of 0.10%, excellent linearity of 0.011%, and a fast frequency response of 500 kHz. These features make it highly applicable in various fields such as new energy vehicles and smart grids, indicating promising prospects for its widespread utilization.

Trampoline-Shaped Micro Electric-Field Sensor for AC/DC High Electric Field Measurement

The measurement of high electric field is widely used in applications such as power grid, electrical equipment, space launch, petroleum industry, and meteorological monitoring. Traditional electric field measurement methods, such as field mills, are bulky and cause electric field distortion. In this article, we presented a trampoline-shaped microelectric field sensor (E-sensor) based on microelectromechanical system (MEMS). The micro E-sensor uses the effect of electrostatic induction, which generates force that drives the vibration of a piezoresistive film and converts the electric field into a differential voltage signal. The presented E-sensor can measure both ac and dc high electric fields with relatively high resolution and wide range. Through experimental measurement, the device exhibits an ac resolution of 172 V/m/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> and a linear measurable electric field range of 312 V/m to over 700 kV/m. The presented E-sensor has good performance with mm-level size and low cost, which could be mass produced for broad applications.

Proposition for sensorless self-excitation by a piezoelectric device

In this paper, we propose a method to realize self-excitation in an oscillator actuated by a piezoelectric device without a sensor. In general, the positive feedback associated with the oscillator velocity causes the self-excitation. Instead of measuring the velocity with a sensor, we utilize the electro-mechanical coupling effect in the oscillator and piezoelectric device. We drive the piezoelectric device with a current proportional to the linear combination of the voltage across the terminals of the piezoelectric device and its differential voltage signal. Then, the oscillator with the piezoelectric device behaves like a third-order system, which has three eigenvalues. The self-excitation can be realized because appropriate feedback gains can set two of the eigenvalues to be conjugate complex roots with a positive real part and the other eigenvalue to be a negative real root. To confirm the validity of the proposed method, we experimentally demonstrated the sensorless self-excitation and, as an application example, carried out mass sensing in a sensorless self-excited macrocantilever.

ASTRE: ASIC with switched capacitor array (SCA) and trigger for detector readout electronics hardened against Single Event Latchup (SEL)

For measuring gamma rays from low energy to high energy and cover the gap between 1 MeV and 300 MeV in space measurements, Time Projection Chambers (TPC) are a promising solution. In order to read the data out of these TPCs, one needs a dedicated electronics to be flexible to cover a wide range of detectors types, with a good resolution over a large dynamic range of incoming charges. The ASTRE chip, a radiation tolerant chip for these applications is described in this article. This Application Specified Integrated Circuit (ASIC) permits the amplification, filtering, triggering and analog storage of 512 samples at a flexible sampling frequency up to 100 MHz. The power consumption is less than 10 mW/channel, with 64 channels per ASIC. The charge range of ASTRE is from 120 fC to 10 pC with 4 programmable gains. The filtering supports 16 peaking times (from 60 ns to 8μs). The ASIC can read negative or positive signals and return a multiplicity signal for triggering and selective readout. In addition it has a programmable internal trigger readable with Low Differential Voltage Signal (LVDS) outputs. The chip was fabricated in August 2016 and is under test. The results of this ASIC to Single Event Latchups, made at the Universite Catholique de Louvain (UCL) are detailed below.

Validating a Multi-Port, Averaging Pitot Tube for Measuring Fan Airflow Rates

A multiport averaging Pitot tube (MAPT) system was evaluated for measuring airflow rates from large agricultural fans in confined poultry facilities. The MAPT system consisted of a copper tube with multiple pressure ports along its length to respond to the velocity pressure profile across the full fan diameter. The tube was connected to a low-pressure transducer that provided a differential voltage signal, which was recorded by a data logger, in response to fan airflow. The best performance was observed when the tubes were positioned on the intake of a test fan and operated with pressure ports facing the downstream direction of the fan. The responses of two tube lengths were calibrated in measuring airflow delivered by a 91- or 122-cm diameter wall-mounted exhaust fan by comparing measurements to a Fan Assessment Numeration System (FANS) used as a reference. There was a strong linear relationship between the square root of voltage outputs from the MAPT pressure sensor and the reference FANS air velocity readings. Linear regression equations were used to compute flow rates of additional fans using MAPT measurement. Airflow rates based on MAPT measurement were highly correlated with the reference FANS values with mean deviation less than 3% and 9% for 91- and 122-cm diameter fans, respectively. The MAPT system is particularly useful for applications such as farm energy audits that require fast and easy estimates of airflow from large, wall-mounted agricultural exhaust fans.

Capacitance and near-infrared techniques for the real-time moisture measurement of broiler litter

The feasibility of capacitance and near-infrared (NIR) techniques for measuring the real-time moisture content (MC) of broiler litter was evaluated. Data collection consisted of recording differential voltage signal and spectral absorption values (1200–2200 nm) for a capacitance and a NIR sensor, respectively, for broiler litter samples within 19.3%–75.1% d.b. (16.2%–42.9% w.b.) MC. Initial data analysis indicated that litter density impacted the capacitance sensor voltage. The sensor generated a linear response between 19.3% and 45.8% d.b. MC at the given bulk density (BD) and the operating moisture range further decreased as the litter BD increased. NIR data analysis indicated that the absorption bands within the 1400–1440 nm and 1900–1950 nm wavelength regions were highly correlated to the litter MC. Linear regression models relating the output data (differential voltage and absorption spectral values for capacitance and NIR, respectively) to the litter MC exhibited a high linear correlation (R2 = 0.89–0.99). Model validation results also generated high correlation values (R2 = 0.87–0.95) between the predicted and measured MC's. Overall results suggested that the NIR technique performed better than the capacitance technique because of its ability to provide rapid, non-intrusive and density-independent measurements within the selected moisture range. The NIR technique is recommended for future real-time moisture measurement on litter conveying and application equipment.