An active temperature compensated fiber Bragg grating vibration sensor for high-temperature application

An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified by a temperature compensation feedback system.The high-temperature vibration sensor is composed of a quartz cantilever beam and a femtosecond Bragg grating.The feedback control demodulation system of active temperature compensation can adjust the laser wavelength to stabilize the grating offset point and realize simultaneous measurement of temperature and vibration.On this basis,the performance of the sensor is tested and analyzed within the range of 20-400℃by setting up a high-temperature vibration test system.The experimental results show that the sensitivity of the sensor is about 132.33 mV/g,and the nonlinearity is about 3.33%.The sensitivity between the laser wavelength and temperature is about 0.01307 nm/℃.In addition,the active temperature compensated fiber Bragg grating vibration sensor has the advantages of a simple structure,stable performance,easy demodulation and high sensitivity.Moreover,the sensor can achieve high temperature vibration signal monitoring and has good practical application value.

All-CMOS temperature compensated current reference

This paper presents a novel temperature independent current reference based on the theory of mutual compensation of mobility and threshold voltage.It is completely compatible with standard CMOS-technology.The experiment results indicate that the temperature coefficient of this current reference is less than 290 ppm/℃over a temperature range from-20 to 110℃.

Temperature compensation method of silicon microgyroscope based on BP neural network

The temperature characteristics of a silicon microgyroscope are studied, and the temperature compensation method of the silicon microgyroscope is proposed. First, an open-loop circuit is adopted to test the entire microgyroscope＇s resonant frequency and quality factor variations over temperature, and the zero bias changing trend over temperature is measured via a closed-loop circuit. Then, in order to alleviate the temperature effects on the performance of the microgyroscope, a kind of temperature compensated method based on the error back propagation（BP）neural network is proposed. By the Matlab simulation, the optimal temperature compensation model based on the BP neural network is well trained after four steps, and the objective error of the microgyroscope＇s zero bias can achieve 0.001 in full temperature range. By the experiment, the real time operation results of the compensation method demonstrate that the maximum zero bias of the microgyroscope can be decreased from 12.43 to 0.75（°）/s after compensation when the ambient temperature varies from -40 to 80℃, which greatly improves the zero bias stability performance of the microgyroscope.

Single-Stage Wide-Range CMOS VGA with Temperature Compensation and Linear-in-dB Gain Control

A novel wide-range CMOS variable gain amplifier （VGA） topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range of 80dB while using a single variable-gain stage. Temperature-compensation and decibel-linear gain characteristic are achieved by using a control circuit that provides a gain error lower than ±1.5dB over the full temperature and gain ranges. Realized in 0.25μm CMOS technology, a prototype of the proposed VGA provides a total gain range of 64.5dB with 55.6dB-linear range,a P-1dB varying from - 17.5 to 11.5dBm,and a 3dB-bandwith varying from 65 to 860MHz while dissipating 16.5mW from a 2.5V supply voltage.

Miniaturized power detection module operating in millimeter wave band

The miniaturized broadband detection module can be embedded into the microwave application system such as the front end of the transmitter to detect the power or other parameters in real time.It is highly prospective in military and scientific research.In this paper,a broadband power detection module operating at 26.5 GHz-40.0 GHz is designed by using low-barrier Schottky diode as the detector and a comparator for threshold output.This module can dynamically detect the power range between-10 dBm and 10 dBm with the detection accuracy of 0.1 dB.Further,the temperature compensation circuit is also applied to improve the measurement error.As a result,the resulted error low to±1 dB in the temperature range of -55℃ to +85℃ is achieved.The designed module is encapsulated by a Kovar alloy with a small volume of 9 mm×6 mm×3 mm.This endows the designed module the advantages of small size,easy integration,and low cost,and even it is applicable to high-reliability environments such as satellites.

Influence of Temperature on the Inter-pressure of Soil Water Tension with Correcting Method

When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ and the inside pressure changed about 14.6 Kpa, when the pottery soil was replaced by the sealing plug. When the soil water was relatively stable in the experimental salvers, the in-side pressure stil varied regularly with the temperature. When the inside temperature increased by 22.2 ℃, the inside pressure varied about 7.4 Kpa. Through com-pensation calculation of the inside tension, the temperature in the warming and cooling periods was compensated, which was useful to correct the tension measurement errors induced from the changing temperature. When the measuring interval was 4 hours and the temperature difference was 18.1 ℃, the tension difference of both points was only 0.278 Kpa, compared to the difference up to 6.5 Kpa before compensation.

A Novel Technique for Improving Temperature Independence of Ring-ADCs

A new temperature compensation technique for ring-oscillator-based ADCs is proposed. This technique employs a novelcfixed-number-based algorithm and CTAT current biasing technology to compensate the temperature-dependent variations of the output, thus eliminating the need for digital calibrations. Simulation results prove that, with the proposed technique,the resolution in the temperature range of 0 to 100℃ can reach a 2mV quantization bin size with an input voltage span of 120mV at the sampling frequency of fs = 100kHz.

HIGH TEMPERATURE DISPLACEMENT SENSOR

A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90-350 mV at 550 ℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2-3 V at 550 ℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550 ℃ in a magnetic bearing system for more than 100 h.

Temperature Compensation Algorithm for Hydraulic System Pressure Control

In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductance and resistance.The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil,which affects the control precision of coil current.First,considering the heat dissipation mode of coil,the coil temperature model is established from the perspective of heat conduction,and a temperature compensation algorithm for hydraulic system pressure control is put forward.Then the hardware-in-the-loop testbed is set up by using the dSPACE platform,carrying out wheel cylinder pressurization tests with inlet valve fully opened at-40℃ and 20℃,and testing the actual pressure of wheel cylinder with the target pressures at-40℃ and 6 000 kPa/s(pressurization rate).The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure.After the correction,the pressure difference is less than 500 kPa,which can meet the control accuracy requirements of solenoid valve,enriching the linear control characteristic of solenoid valve.

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances.While strain gauge technology is very mature,piezoresistive semiconductor sensors offer alternatives that are worth exploring to assess their unique benefits,such as better strain resolution and accuracy,which would enable balances to be designed with higher factors to safety and hence longer fatigue lifetimes.A new three-component balance,based on temperature compensated semiconductor strain gauges,is designed,calibrated and tested in a hypersonic low density wind tunnel.The static accuracy of the semiconductor balance is calibrated better than 0.3%FS,and the dynamic accuracy of the balance is established using a HB-2 standard model in a Mach 12 hypersonic flow.Good experimental repeatability is confirmed to be better than 2.5%FS,and the effectiveness of the balance is demonstrated by comparing the forces and moments of measured data with computational fluid dynamics simulations,as well as reference wind tunnel results under similar conditions.

Curvature Compensated CMOS Bandgap Reference with Novel Process Variation Calibration Technique

A lowtemperature coefficient（ TC） bandgap reference（ BGR） with novel process variation calibration technique is proposed in this paper. This proposed calibration technique compensating both TC and output value of BGR achieves fine adjustment step towards the reference voltage,while keeping optimal TC by utilizing large resistance to help layout match. The high-order curvature compensation realized by poly and p-diffusion resistors is introduced into the design to guarantee the temperature characteristic. Implemented in 180 nm technology,the proposed BGR has been simulated to have a power supply rejection ratio（ PSRR） of 91 dB@100 Hz. The calibration technique covers output voltage scope of 0. 49 V-0. 56 Vwith TC of 9. 45 × 10^（-6）/℃-9. 56 × 10^（-6）/℃ over the temperature range of-40 ℃-120 ℃. The designed BGR provides a reference voltage of 500 mV,with measured TC of 10. 1 × 10^（-6）/℃.

Experimental Study of Effect of Temperature Variations on the Impedance Signature of PZT Sensors for Fatigue Crack Detection

Structural health monitoring(SHM)is recognized as an efficient tool to interpret the reliability of a wide variety of infrastructures.To identify the structural abnormality by utilizing the electromechanical coupling property of piezoelectric transducers,the electromechanical impedance(EMI)approach is preferred.However,in real-time SHM applications,the monitored structure is exposed to several varying environmental and operating conditions(EOCs).The previous study has recognized the temperature variations as one of the serious EOCs that affect the optimal performance of the damage inspection process.In this framework,an experimental setup is developed in current research to identify the presence of fatigue crack in stainless steel(304)beam using EMI approach and estimate the effect of temperature variations on the electrical impedance of the piezoelectric sensors.A regular series of experiments are executed in a controlled temperature environment(25°C–160°C)using 202 V1 Constant Temperature Drying Oven Chamber(Q/TBXR20-2005).It has been observed that the dielectric constantð"33 TÞwhich is recognized as the temperature-dependent constant of PZT sensor has sufficiently influenced the electrical impedance signature.Moreover,the effective frequency shift(EFS)approach is optimized in term of significant temperature compensation for the current impedance signature of PZT sensor relative to the reference signature at the extended frequency bandwidth of the developed measurement system with better outcomes as compared to the previous literature work.Hence,the current study also deals efficiently with the critical issue of the width of the frequency band for temperature compensation based on the frequency shift in SHM.The results of the experimental study demonstrate that the proposed methodology is qualified for the damage inspection in real-time monitoring applications under the temperature variations.It is capable to exclude one of the major reasons of false fault diagnosis by compensating the consequence of elevated temperature at extended frequency bandwidth in SHM.

The dynamic compensation temperature in a kinetic spin-5/2 Ising model on a hexagonal lattice

We present a study of the dynamic behavior of a two-sublattice spin-5/2 Ising model with bilinear and crystal-field interactions in the presence of a time-dependent oscillating external magnetic field on alternating layers of a hexagonal lattice by using the Glauber-type stochastic dynamics.The lattice is formed by alternate layers of spins σ=5/2 and S=5/2.We employ the Glauber transition rates to construct the mean-field dynamic equations.First,we investigate the time variations of the average sublattice magnetizations to find the phases in the system and then the thermal behavior of the dynamic sublattice magnetizations to characterize the nature（first-or second-order） of the phase transitions and to obtain the dynamic phase transition（DPT） points.We also study the thermal behavior of the dynamic total magnetization to find the dynamic compensation temperature and to determine the type of the dynamic compensation behavior.We present the dynamic phase diagrams,including the dynamic compensation temperatures,in nine different planes.The phase diagrams contain seven different fundamental phases,thirteen different mixed phases,in which the binary and ternary combination of fundamental phases and the compensation temperature or the L-type behavior strongly depend on the interaction parameters.

Temperature Compensation for Double Fiber Bragg Grating Sensors

A novel double fiber Bragg grating（FBG） strain sensor configuration is presented. Temperature compensation method is based on double FBG moored on a rhombus frame. Through the theoretical analysis, the relation between relative shift of Bragg wavelength and the strain applied on the sensor is obtained, and the analytical expression of strain sensitivity coefficient is also given. The experiment results show that： in the strain range of 0-0. 8 mm, the relation between the relative shift of Bragg wavelength and applied strain is linear, and the dispersion of double FBG wavelength at the range of -25℃- 60℃ is 0-0. 002 nm. The strain sensitivity of the displacement sensor configuration is 0. 171 nm/με, and is nearly twice than that of single FBG sensor.

Symmetric Temperature Compensation for Photoelectric Coupling Current Transducer

The temperature characteristic of sensor probe at high voltage side is analyzed by using a photoelectric coupling current transducer. The principle of symmetric temperature compensation and the main idea of software design are proposed. The method increases measuring precision and has fairly great practicability.

Temperature compensation method for low cost three-axis MEMS digital angular rate gyroscopes

In recent years,a large number of small volume,low cost micro electro mechanical systems（MEMS）digital three-axis angular rate gyroscopes have been developed and widely used in civil and military fields.However,these kinds of gyroscopes have poor performances in initial zero-bias,temperature drift,In-Run bias stability,bias repeatability,etc.,their output errors need to be compensated before being used.Based on a lot of experiments,the temperature drift and the initial zero-bias are the major error sources in the MEMS gyroscopes output data.Due to the poor repeatability of temperature drift,the temperature compensation coefficients need to be recalculated every time before using.In order to recalculate parameters of the temperature compensation model quickly,a 1st-order polynomial model of temperature is established,then a forgetting factor recursive least squares estimator will be adopted to identify the model parameters in real time.Static and dynamic experimental data shows that this method removed/compensated the temperature drift and initial zero-bias from the output of the gyroscopes effectively.

Compensation temperatures and hysteresis behaviors of a graphene-like trilayer

This work focuses on the ground-state phase diagram,the compensation temperatures and the critical behaviors of a ferrimagnetic graphene-like trilayer induced by crystal fields and exchange couplings.The simulation results show that a negative decrease in crystal field or an increase in exchange coupling can increase the critical temperature.More importantly,an M curve with double compensation temperatures can be observed,which is not predicted by the Neel theory.This remarkable compensation phenomenon has potential application value in the field of magnetic recording.

Thermostability of Vane Absorber

Aim To improve the thermostability of vane absorbers while designing and manu- facturing. Methods Having considered the structural features of vane absorbers, measures that could reduce the force decay ratio of vane absorbers were discussed. A kind of practical auto temperature compensation apparatus, whose theoretical basis had been discussed, was designed. Results Compared to the prototype vane absorber, this kind of apparatus could decrease force decay ratio sharply. Thus, the thermostability of vane absorbers was improved greatly The accuracy of theoretical analysis and the effectiveness and feasibility of the apparatus was proved by actual testing Conclusion changing vane absorber's configuration, its performance is improved.

Implementation of a DC-10Mb/s 0.5μm CMOS Laser Diode Driver

A DC-10Mb/s laser diode driver,compatible with TTL and CMOS levels,is presented. The optical power corresponding to‘1＇ and ‘0＇ can be set independently with resistors off-chip and stabilized with a closed loop. A novel peak-to- peak optical power monitor and stabilization mechanism is introduced. The circuit, fabricated in a CSMC 0. 5μm mixed signal CMOS process, can provide 120mA maximum drive current and 0. 6dB extinction ration fluctuation over - 20 ＋ 80℃ ,which is independent of input pattern.

A Low Voltage,Low Power RF/Analog Front-End Circuit for Passive UHF RFID Tags

This paper presents a low voltage, low power RF/analog front-end circuit for passive ultra high frequency （UHF） radio frequency identification （RFID） tags. Temperature compensation is achieved by a reference generator using sub-threshold techniques. The chip maintains a steady system clock in a temperature range from - 40 to 100℃. Some novel building blocks are developed to save system power consumption,including a zero static current power-on reset circuit and a voltage regulator. The RF/analog front-end circuit is implemented with digital base-band and EEPROM to construct a whole tag chip in 0. 18μm CMOS EEPROM technology without Schottcky diodes. Measured results show that the chip has a minimum supply voltage requirement of 0.75V. At this voltage, the total current consumption of the RF/analog frontend circuit is 4.6μA.