基于PID自校准算法的IGBT温升控制实现

针对功率循环实验中绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)温度过冲和滞后问题,设计了一种自校准PID算法控制IGBT温升.通过MATLAB进行PID建模及参数仿真,采用电学法测试原理并结合嵌入式系统测试IGBT结温,使用PID自校准算法控制器件温升进行IGBT热疲劳测试.实验结果表明:该算法的调节方式和温度精度都达到理想的效果,改善了系统的动态性能,为IGBT寿命预测提供了一个良好的实验环境.

On joint analysing XMM-NuSTAR spectra of active galactic nuclei

A recently released XMM-Newton note revealed a significant calibration issue between nuclear spectroscopic telescope array(NuSTAR)and XMM-Newton European Photon Imaging Camera(EPIC)and provided an empirical correction to the EPIC effective area.To quantify the bias caused by the calibration issue in the joint analysis of XMM-NuSTAR spectra and verify the effectiveness of the correction,in this work,we perform joint-fitting of the NuSTAR and EPIC-pn spectra for a large sample of 104 observation pairs of 44 X-ray bright active galactic nuclei(AGN).The spectra were extracted after requiring perfect simultaneity between the XMM-Newton and NuSTAR exposures(merging good time intervals(GTIs)from two missions)to avoid bias due to the rapid spectral variability of the AGN.Before the correction,the EPIC-pn spectra are systematically harder than the corresponding NuSTAR spectra by■subsequently yielding significantly underestimated cutoff energy E_(cut)and the strength of reflection component R when performing joint-fitting.We confirm that the correction is highly effective and can commendably erase the discrepancy in best-fitΓ,E_(cut),and R.We thus urge the community to apply the correction when joint-fitting XMM-NuSTAR spectra,but note that the correction is limited to 3–12 keV and therefore not applicable when the soft X-ray band data are included.Besides,we show that as merging GTIs from two missions would cause severe loss of NuSTAR net exposure time,in many cases,joint-fitting yields no advantage compared with utilizing NuSTAR data alone.Finally,We present a technical note on filtering periods of high background flares for XMM-Newton EPIC-pn exposures in the small window(SW)mode.

Research on measuring time constant of NANMAC thermocouple

The theory for measuring the time constant of thermocouple was introduced, and the method for measuring the time constant of NANMAC thermocouple by using dynamic calibration system of transient surface temperature sensor was proposed. In this system, static and dynamic calibrations were conducted for infrared detectors and thermocouples, and then both temperature-time curves were obtained. Since the frequency response of infrared detector is superior to that of calibrat- ed thermocouple, the values measured by infrared detectors are taken as true values. Through dividing the values measured with thermocouples by those with infrared detectors, a normalized curve was obtained, based on which the time constant of thermocouple was measured. With this method, the experiments were carried out with NANMAC thermocouple to obtain its time constant. The results show that the method for measuring the time constant is feasible and the dynamic calibration of thermocouples can be achieved at microsecond and millisecond level. This research has a certain reference value for research and application of NANMAC thermocouple temperature sensor.

Research on thermocouple transient thermometry technology based on LabVIEW

Based on LabVlEW platform, a distributed dynamic storage testing system is designed for measuring transient high temperature signals of explosion field. Using a highpower semiconductor laser as heat source, a traceable dynamic calibration system is established to perform dynamic calibration of thermocouples. With quantumbehaved particle swam optimization （QP-SO） algorithm on MATLAB platform, a model of dynamic compensation filter is established. It is used by LabVIEW that calls MATLAB Script nodes or COM components to accomplish the mixed programming of LabVIEW and MATLAB, further to compensate the temperature values of the thermocouples dynamically. The experimental results show that the technique that combines temperature measurement system with LabVIEW platform is applied well in testing the explosion temperature of ther mobaric weaponry and makes the compensation values closer to the actual signals.

Research on dynamic error compensation for an armored K type thermocouple

A new method was proposed, in which a high-power CO2 laser modulated by high frequency was used as the driv- ing source to heat up a surface-temperature sensor. The continual beam and the pulsed beam sent out by the same laser could be used in the same system to carry on the static calibration of the radiation thermometer and the dynamic calibration of the temperature sensor to be checked. The frequency-response characteristics of high-speed radiation thermometer surpassed that of the temperature sensor, therefore it could be used as the reference value to calibrate the latter and let system error be cor- rected. Differences in the environment of the sensor installing and the error caused by the change of thermo-physical proper- ty could be avoided. Thus, the difficult problem of traceable dynamic calibration of temperature was solved. In experiment, to obtain the frequency characteristics of the thermocouple and the dynamic performance of the K type thermocouple, which could compensate the dynamic characteristics of the sensor, the sensor was dynamically corrected by using the method, and then the mathematical model was established.

A Novel Offset-Cancellation Technique for Low Voltage CMOS Differential Amplifiers

Based on a physical understanding of nonlinearity and mismatch, a novel offset-cancellation technique for low voltage CMOS differential amplifiers is proposed. The technique transfers the offset voltage from the output to other parts of the differential amplifier and can greatly reduce the input-referred offset voltage without extra power consumption. A 1.8V CMOS differential amplifier is implemented in 0.18μm CMOS process using the proposed technique. The simulation results show that the technique could reduce the input-referred offset voltage of the amplifier by 40% with a 20% load transistor mismatch and a 10% input differential transistor mismatch. Moreover, the proposed technique consumes the least power and achieves the highest integration among various offset-cancellation techniques.

A Piecewise-Linear Compensated Bandgap Reference

A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some sub ranges.At different temperature sub ranges the bandgap reference can be compensated by different linear functions.Since the temperature sub range is much narrower than the whole range,the compensation error can be reduced significantly.Theoretically,the precision can be improved unlimitedly if the sub ranges are narrow enough.In the given example,with only three temperature sub ranges,the temperature coefficient of a conventional bandgap reference drops from 1 5×10 -5 /℃ to 2×10 -6 /℃ over the -40℃ to 120℃ temperature range.

A Fractional-N CMOS DPLL with Self-Calibration

A digital phase-locked loop （DPLL） based on a new digital phase-frequency detector is presented. The self-calibration technique is employed to acquire wide lock range,low jitter, and fast acquisition. The DPLL works from 60 to 600MHz at a supply voltage of 1.8V. It also features a fraetional-N synthesizer with digital 2nd-order sigma-delta noise shaping, which can achieve a short lock time,a high frequency resolution,and an improved phase-noise spectrum. The DPLL has been implemented in SMIC 0. 18μm 1.8V 1P6M CMOS technology. The peak-to-peak jitter is less than 0. 8% of the output clock period and the lock time is less than 150 times of the reference clock period after the pre-divider.

A High Phase Accuracy and Low Amplitude Mismatch Quadrature LO Driver

A 1.1 - 1.2GHz CMOS high phase accuracy,low amplitude mismatch quadrature LO driver is presented,which consists of a high frequency amplifier,an integrated poly phase filter, and an I/Q phase and magnitude calibration circuit（PMCC）. The proposed PMCC uses a feed-forward calibration technique. It improves the phase accuracy and reduces the amplitude mismatch with low power consumption. Simulation results show that phase error with PMCC is reduced to about one half and the amplitude mismatch is reduced to about one tenth, when compared to the LO driver without PMCC. Moreover,the calibration circuit also functions as a buffer to drive mixers, thus no additional buffer is needed in this design. The LO driver is implemented in a TSMC 0.25μm CMOS process. Experimental results show that the LO driver achieves high quadrature accuracy （〈2°） and low amplitude mismatch （0. 1%）. It has about 5.25dB gain and dissipates 6mA from the 2.5V power supply. The size of the die area is only 1.0mm×1.0mm.

Capacitor self-calibration technique used in time-interleaved successive approximation ADC

A capacitor self-calibration circuit used in a successive approximation analog-to-digital converter （SA-ADC） is presented. This capacitor self-calibration circuit can calibrate erroneous data and work with the ADC by adding an additional clock period. This circuit is used in a 10 bit 32 Msample/s time-interleaved SA- ADC. The chip is implemented with Chart 0. 25 μm 2. 5 V process and totally occupies an area of 1.4 mm× 1.3 mm. After calibration, the simulated signal-to-noise ratio （SNR） is 59. 586 1 dB and the spurious-free dynamic range （SFDR） is 70. 246 dB at 32 MHz. The measured signal-to-noise and distortion ratio （SINAD） is 44. 82 dB and the SFDR is 63. 760 4 dB when the ADC samples a 5.8 MHz sinusoid wave.

Design of foundation structures of sea-crossing bridges on serviceability limit state

The target reliability indices of the foundation structures of sea-crossing bridges on the serviceability limit state （SLS） are different from those of common bridges due to their different surroundings. Consequently, three levels of the target reliability indices, which are 1.5, 2. 0 and 2. 3, respectively, for those structures on the SLS are suggested based on the Joint Committee on Structural Safety （JCSS） model code, and a new method of calibrating factors of live loads, which is based on the contribution ratio of tensile stresses of reinforcing bars produced by various loads to the maximum crack width of concrete, is proposed. Finally, the calibration of the reliability-based factors of the frequent value and the quasi-permanent value of live loads is conducted by the Joint Committee （JC） method through an actual design, and the indices are proved to be reasonable and the new method is proved to be feasible.

Fitting V F Converter*ss Output Using High Order Neural Networks

A new method is presented in this paper for fitting VFC*ss (voltage to frequency converter) output functions by using high order neural networks. The nonlinear estimation is implemented when the VFC110 is used at a full scale output frequency of 4 MHz. Two kinds of on line dynamic calibrating circuits are designed to improve the sampling precision. This method can also be applied to different industrial applications.

Automatic IQ Phase Calibration Design in a 2.4GHz Direct Conversion Receiver

An automatic IQ phase calibration method implemented in a 2.4GHz direct conversion receiver is proposed. It uses a delay locked loop （DLL） with a proposed quadrature phase detector to greatly reduce the phase error. The receiver is fabricated in a 0.18μm CMOS process. Measurements show that the IQ phase error can be calibrated within 1°,which satisfies the system requirement.

A Σ-Δ Fractional-N PLL Frequency Synthesizer with AFC for SRD Applications

A fractional-N frequency synthesizer for 433/868MHz SRD applications is implemented in a 0.3μm CMOS process. A wide-band VCO and an AFC are used to cover the desired bands. A 3bit third order sigma-delta modulator is adopted to reduce the out-band phase noise. The measurements show a VCO tuning range from 1.31 to 1.88GHz with AFC working correctly,an out-band phase noise of -139dBc/Hz at 3MHz offset frequency, and a fractional spur of less than - 60dBc. The chip area is 1.5mm × 1.2mm and the total current dissipation including LO buffers is 19mA from a single 3.0V supply voltage.

Calibration of Soil Electromagnetic Conductivity in Inverted Salinity Profiles with an Integration Method

Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth.

A 5-GHz frequency synthesizer with constant bandwidth for low IF ZigBee transceiver applications

A fully integrated integer-N frequency synthesizer is implemented.The synthesizer is designed for low intermediate frequency （IF）ZigBee transceiver applications.Techniques used to make the loop bandwidth constant across the whole output frequency range of the voltage controlled oscillator（VCO）are adopted to maintain phase noise optimization and loop stability.In-phase and quadrature（IQ）signals are generated by a 1/2 frequency divider at the output of the VCO.The synthesizer is fabricated in 0.18 μm radio frequency（RF） complementary metal oxide semiconductor transistor （CMOS）technology.The chip area is 1.7 mm2.The synthesizer is measured on wafer.It consumes totally 28.8 mW excluding output buffers from a supply voltage of 1.8 V.The measured phase noise is -110 and -122 dBc/Hz at the offset of 1 and 3 MHz from a 2.405 GHz carrier,respectively.The measured reference spur at a 2 MHz offset from a 2.405 GHz carrier is-48.2 dBc.The measured setting time of the synthesizer is about 160 μs.

Measurement of 3db Bandwidth of Laser Diode Chips

An accurate technique for measuring the frequency response of semiconductor laser diode chips is proposed and experimentally demonstrated.The effects of test jig parasites can be completely removed in the measurement by a new calibration method.In theory,the measuring range of the measurement system is only determined by the measuring range of the instruments network analyzer and photo detector.Diodes' bandwidth of 7 5GHz and 10GHz is measured.The results reveal that the method is feasible and comparing with other method,it is more precise and easier to use.

Mismatch Calibration Techniques in Successive Approximation Analog-to-Digital Converters

Comparator offset cancellation and capacitor self-calibration techniques used in a successive approximation analog-to-digital converter （SA-ADC） are described. The calibration circuit works in parallel with the SAADC by adding additional calibration clock cycles to pursue high accuracy and low power consumption, and the calibrated resolution can be up to 14bit. This circuit is used in a 10bit 3Msps successive approximation ADC. This chip is realized with an SMIC 0. 18μm 1.8V process and occupies 0.25mm^2 . It consumes 3. 1mW when operating at 1.8MHz. The measured SINAD is 55. 9068dB, SFDR is 64. 5767dB, and THD is - 74. 8889dB when sampling a 320kHz sine wave.

Tetramethylpyrazine stimulates cystic fibrosis transmembrane conductance regulator-mediated anion secretion in distal colon of rodents

AIM： To investigate the effect of tetramethylpyrazine （TMP）, an active compound from Ligustium Wollichii Franchat, on electrolyte transport across the distal colon of rodents and the mechanism involved.METHODS： The short-circuit current （Isc） technique in conjunction with pharmacological agents and specific inhibitors were used in analyzing the electrolyte transport across the distal colon of rodents. The underlying cellular signaling mechanism was investigated by radioimmunoassay analysis （RIA） and a special mouse model of cystic fibrosis.RESULTS： IMP stimulated a conoentration-dependent rise in ISCl, which was dependent on both Cl^- and HCO3^-, and inhibited by apical application of diphenylamine-2,2＇-dicarboxylic acid （DPC） and glibenclamide, but resistant to 4,4＇-diisothiocyanatostilbene-2,2＇-disulfonic acid disodium salt hydrate （DIDS）. Removal of Na^＋ from basolateral solution almost completely abolished the Isc response to TMP, but it was insensitive to apical Na^＋ replacement or apical Na^＋ channel blocker, amiloride. Pretreatment of colonic mucosa with BAPTA-AM, a membrane-permeable selective Ca2＋ chelator, did not significantly alter the TMP-induced Iso No additive effect of forskolin and 3-isobutyl-l-methylxanthine （[BMX） was observed on the TMP-induced Isc, but it was significantly reduced by a protein kinase A inhibitor, H89.RIA results showed that TMP （1 mmol/L） elicited a significant increase in cellular cAMP production, which was similar to that elicited by the adenylate cyclase activator, forskolin （10μmol/L）. The TMP-elicited Isc as well as forskolin- or IBMX-induced Isc were abolished in mice with homozygous mutation of the cystic fibrosis transmembrane conductance regulator （CFTR） presenting defective CFTR functions and secretions.CONCLUSION： TMP may stimulate cAMP-dependent and CFTR-mediated Cl^- and HCO3^- secretion. This may have implications in the future development of alternative treatment for constipation.