电涡流传感器热稳定性标定技术

介绍电涡流传感器位移测量原理,分析温度变化时传感器线圈和探头热胀冷缩在测量位移过程中造成的温度漂移现象.针对传感器的温漂,研制出具有温度补偿功能的电涡流传感器热稳定性标定装置,对传感器输出电压进行温度补偿,减小温度变化对传感器输出电压的影响.同时介绍利用该装置进行温度标定的实现方法,并进行实验验证,实现固定位移条件下环境温度变化时对电涡流传感器输出电压的标定,与无温度补偿时输出电压对比,电压变化量减小了近50%.     

Wire-bonding process monitoring using thermopile temperature sensor

This work presents an approach to separate the thermal response due to ultrasonic excitation and ball deformation through novel application of aluminum-polysilicon thermopile sensors under the bond pad. These integrated thermopile sensors measure temperature at a radial distance under the bond pad, in contrast to the previously reported average measurements over the bond pad interface or around the bond pad over a radial distance. The high sensitivity and signal-to-noise ratio (SNR) of the sensor allow direct measurements of the signal, without any amplification or filtration. Transient temperature variations at two radial locations were obtained using two versions of thermopile sensor designs. The sensor response was interpreted using representative finite-element thermal modeling for the process. Results from modeling reveal that the thermal response is a strong function of radial location. These results also reveal that the thermal response due to interfacial heating is significantly higher under the bond pad, as compared to that around the bond pad. This is in agreement with the experimental observations. Critical points on the temperature variation curve were identified. These points can be used to correlate the sensor response to shear test data. Once the sensor response is calibrated, it can be used to monitor the bonding process. Measurements were performed at substrate temperatures of 150/spl deg/C and 200/spl deg/C, along with the microwelds characterization at the bonding interface. The comparison of the thermal response and the microwelds at the two substrate temperatures revealed that in order to correlate the sensor response to shear test data, the response must be obtained at the intended temperature of operation since the microwelds at two temperatures may be quite different, even though thermal responses may look similar.     

A time-to-digital-converter-based CMOS smart temperature sensor

A time-to-digital-converter-based CMOS smart temperature sensor without a voltage/current analog-to-digital converter (ADC) or bandgap reference is proposed for high-accuracy portable applications. Conventional smart temperature sensors rely on voltage/current ADCs for digital output code conversion. For the purpose of cost reduction and power savings, the proposed smart temperature sensor first generates a pulse with a width proportional to the measured temperature. Then, a cyclic time-to-digital converter is utilized to convert the pulse into a corresponding digital code. The test chips have an extremely small area of 0.175 mm/sup 2/ and were fabricated in the TSMC CMOS 0.35-/spl mu/m 2P4M process. Due to the excellent linearity of the digital output, the achieved measurement error is merely -0.7/spl sim/+0.9/spl deg/C after two point calibration, but without any curvature correction or dynamic offset cancellation. The effective resolution is better than 0.16/spl deg/C, and the power consumption is under 10 /spl mu/W at a sample rate of 2 samples/s.     

Temperature measurement in rapid thermal processing using theacoustic temperature sensor

Acoustic techniques are used to monitor the temperature of silicon wafers in rapid thermal processing environments from room temperature to 1000°C with ±5°C accuracy. Acoustic transducers are mounted at the bases of the quartz pins that support the silicon wafer during processing. An electrical pulse applied across the transducer generates an extensional mode acoustic wave which is guided by the quartz pins. The extensional mode is converted into Lamb waves (a guided plate mode) in the silicon wafer which acts as a plate waveguide. The Lamb wave propagates across the length of the silicon wafer and is converted back into an extensional mode at the other pin. The extensional mode acoustic wave is detected and the total time of flight is obtained. The time of flight of the extensional mode in the quartz pin is measured using pulse echo techniques and is subtracted from the total time of flight. Because the velocity of Lamb waves in the silicon wafer is systematically affected by temperature, the measurement of the time of flight of the Lamb wave provides the accurate temperature of the silicon wafer. The current implementation provides a ±5°C accuracy at 20 Hz data rate. Further improvements in electronics and acoustics should enable ±1°C measurements. The acoustic temperature sensor (ATS) has several advantages over conventional temperature measurement techniques. Unlike pyrometric measurements, ATS measurements are independent of emissivity of the silicon wafer and will operate down to room temperature. ATS also does not have the contact and contamination problems associated with thermocouples     

Implementation of a fast relative digital temperature sensor to achieve thermal protection in Zynq SoC technology

More and more industrial embedded systems are developed to undergo hard environmental conditions, especially high temperatures. To prevent this impact, environmental conditions (e.g. the temperature) could be monitored. Plenty of new industrial designs are built around SoCs, and more especially around the Zynq-7000 introduced by Xilinx in 2011. In fact, monitoring the temperature inside the Zynq has become a challenge. While many applications focused on precision, the application proposed here instead is in an industrial context and aims at detecting a temperature excess as fast as possible to achieve the thermal protection of a logic area of the chip. Most of the digital sensors designed require a calibration to be operational. Such a process is not viable for time to market, and a solution must be found to either lighten it (e.g. by doing a simple 3-points calibration) or simply avoiding it. Instead of measuring the temperature in an absolute way, this paper focuses on detecting if the temperature is above or below a threshold. This work exhibits the implementation of three temperature digital sensors with promising results on Zynq technology. Two of the presented sensors are based on a ring-oscillator and another uses a flip-flop as a sensing element. Results show that a temperature increase can be detected in less than 1ms without any calibration protocol and this sensor was found to perfectly fit the targeted application.     

Micropower CMOS temperature sensor with digital output

A CMOS smart temperature sensor with digital output is presented. It consumes only 7 μW. To achieve this extremely low-power consumption, the system is equipped with a facility that switches off the supply power after each sample. The circuit uses substrate bipolars as a temperature sensor. Conversion to the digital domain is done by a sigma-delta converter which makes the circuit highly insensitive to digital interference. The complete system is realized in a standard CMOS process and measures only 1.5 mm². In the temperature range from -40 to +120°C, the inaccuracy is ±1°C after calibration at two temperatures. The circuit operates at supply voltages down to 2.2 V     

Reliability aspects of thermal micro-structures implemented on industrial 0.8 μm CMOS chips

This paper discusses the reliability characterization of thermal micro-structures implemented on industrial 0.8 μm CMOS chips. Various degradation and failure mechanisms are identified and evaluated under high temperature operation. At high temperatures the mechanisms are many and varied, and co-incidental thermally-induced mechanical defects are found in both the poly-Si heater and the poly-Si temperature sensor, along with temperature- and current-enhanced interlayer diffusion degradation of the heater contacts. Local reduction in the device thermal capacity by using silicon micro-machining can be expected to hold the promise of a number of significant advantages, especially for limiting current stressing of the contact regions. The results can be used to optimize the design of thermally based micro-sensors on CMOS chips, such as CMOS compatible chemoresistive gas sensors.     

A cost-effective flexible MEMS technique for temperature sensing

A simplified, cost-effective flexible micro-electronic-mechanical systems (MEMS) technology has been developed for realizing a temperature-sensing array on a flexible polyimide substrate. The fabrication technique utilized liquid polyimide to form flexible film on the rigid silicon wafer using a temporary carrier during the fabrication. The platinum thin film is employed as temperature sensitive material and 8×8 temperature-sensing arrays were micromachined on the polyimide, from which the silicon wafer carrier was removed at the end of fabrication. The platinum thin film temperature sensor exhibits excellent linearity and its temperature coefficient of resistance reaches 0.00291 °C⁻¹. Because of the effective thermal isolation, the flexible temperature sensors show a high sensitivity of 1.12 Ω/°C at 10 mA to the constant drive current. The flexible MEMS technology based on liquid polyimide enables the development of flexible, compliant, robust, and multi-modal sensor skins for many other important applications, such as robotics, biomedicine, and wearable microsystems.     

采用双窗口红外探测器的道面温度遥测系统

在外场应用环境中,红外道面温度遥测系统的自身温度会发生较大幅度的变化,引起的内部杂散辐射变化会导致较大的系统测量误差。设计了采用双窗口红外探测器的红外道面温度遥测系统,同时对目标物辐射和内部杂散辐射进行实时测量,并在考虑探测器温度效应的基础上,建立了扣除内部杂散辐射影响的道面温度计算模型;标定实验结果表明:当探测器工作温度和测量目标温度分别在?10~40 ℃、?10~60 ℃范围时,探测器温度效应和辐射定标函数均可以做线性化处理,并呈线性叠加效果,验证了道面温度计算模型的合理性;经过标定后,红外道面温度遥测系统与Pt100接触式温度传感器进行了外场比对测试,得到测量系统与Pt100接触式温度传感器的测量数据相关性达到98.7%,其中夜间测量误差低于2.78%,表明了系统可在环境温度变化的外场条件下准确测量道面温度。     

基于靶标辐射元的IR-JST温度反演方法研究

红外成像干扰模拟靶标(JST)用以在红外成像导引系统(IRIGS)抗干扰性能测试中为IRIGS提供干扰源,目前普遍采用的数字仿真法受仿真精度的制约不能准确的模拟各类干扰源,为此本文提出了一种基于热电器件阵列的红外成像干扰模拟靶标生成方法。但是实验中发现在热像仪温度反演过程中,利用传统的黑体定标方法将引入发射率补偿误差,并且随着工作时间的增加,热像仪发生温度漂移现象,严重的影响了热像仪温度反演精度。针对以上问题,提出了一种基于靶标敏感单元的热像仪标定方法及漂移补偿算法,实验结果表明,该方法能够使热像仪温度反演误差由7℃降低至0.5℃。     

A cross-coupled-structure-based temperature sensor with reduced process variation sensitivity

An innovative,thermally-insensitive phenomenon of cascaded cross-coupled structures is found.And a novel CMOS temperature sensor based on a cross-coupled structure is proposed.This sensor consists of two different ring oscillators.The first ring oscillator generates pulses that have a period,changing linearly with temperature.Instead of using the system clock like in traditional sensors,the second oscillator utilizes a cascaded cross-coupled structure to generate temperature independent pulses to capture the result from the first oscillator.Due to the compensation between the two ring oscillators,errors caused by supply voltage variations and systematic process variations are reduced.The layout design of the sensor is based on the TSMC13G process standard cell library.Only three inverters are modified for proper channel width tuning without any other custom design.This allows for an easy integration of the sensor into cell-based chips.Post-layout simulations results show that an error lower than±1.1℃ can be achieved in the full temperature range from-40 to 120℃.As shown by SPICE simulations,the thermal insensitivity of the cross-coupled inverters can be realized for various TSMC technologies:0.25/μm,0.18μm,0.13μm,and 65 nm.     

A method for heat flow resistance measurements in avalanche diodes

Avalanche transit time oscillators are operating at power densities approaching 10⁶W/cm², unprecedented in semiconductor device history. At such power densities, heat flow resistance problems at the interface between the flip-chip mounted silicon chips and the metal substrate, as well as between the package and the heat sink, are extremely critical. This paper describes a new, nondestructive and accurate method of measuring the heat flow resistance between junction and heat sink by utilizing the temperature dependent breakdown voltage Vb(T) as a conveniently built-in temperature sensor. Variations in junction temperature ΔT with power ΔP= VbΔI are, therefore, related to variations in breakdown voltage ΔVbwith current ΔI resulting in a contribution to the electrical small signal resistance of the diode. This thermal resistance contribution Rthcan be separated readily from spreading and space charge resistance Rapand Rscbecause of the frequency dependence of Rth(ω). Furthermore, the frequency dependence of Rth(ω) allows the separation of heat flow resistance contributions originating in the immediate vicinity of the junction (Si-metal interface) from contributions originating at a poor thermal contact between package and heat sink. In keeping with calculations on simplified geometrical configurations, for which analytical solutions of the frequency dependent heat flow in a distributed circuit could be obtained, experimental results are presented which indicate that both heat flow resistance contributions can be extracted and separated with sufficient accuracy from as few as three electrical resistance measurements, e.g., at dc, 100 Hz, and 1 MHz. The simplicity of such measurements and their evaluation make this technique ideal for in-line testing of production devices.     

An accurate biomedical temperature transducer with on-chipmicrocomputer interfacing

The authors describe a novel smart temperature sensor with on-chip signal processing. The output signal consists of a temperature-dependent frequency and a reference frequency that are time-multiplexed and can be read out by a microcomputer. This sensor, which has been designed for biomedical applications, has an accuracy of ±0.1°C in the temperature range of 32-44°C and a minimum supply voltage of only 2.5 V     

A switched-current, switched-capacitor temperature sensor in0.6-μm CMOS

A temperature-to-digital converter is described which uses a sensor based on the principle of accurately scaled currents in the parasitic substrate p-n-p in a standard fine-line CMOS process. The resulting PTAT δV_BE signal is amplified in an auto-zeroed switched-capacitor circuit, sampled, and converted to a digital output by a low-power 10-bit SAR ADC providing a resolution of 0.25° from -55°C to 125°C with an error of less than 1°. A single adjustment of temperature error is provided for wafer probe. No further calibration is required. A switching bandgap reference circuit will also be described which uses similar techniques to generate an accurate low-noise reference voltage for the ADC. The circuits are part of a multichannel data-acquisition system where other input voltages must also be sampled and measured, and so the speed and power of the ADC is not determined by the temperature sensor alone. For continuous operation, the supply current is 1 mA, but a low-power mode is provided where the part is normally in shut down and only powers up when required. In this mode, the average power supply current at 10 conversions/s is 0.3 μA. The supply voltage is 2.7-5.5 V     

A novel semiconductor capacitive sensor for a single-chipfingerprint sensor/identifier LSI

We describe a new semiconductor capacitive sensor structure and the fabrication process for a single-chip fingerprint sensor/identifier LSI in which the sensor is stacked on a 0.5-μm CMOS LSI. To ascertain the influence of the fabrication process and normal usage on the underlying LSI, sensor chips were subjected to an electrostatic discharge (ESD) test, mechanical stress test, and unsaturated pressure cooker test (USPCT). ESD tolerance is obtained at the value of ±3.0 kV. To investigate mechanical stress, we carried out a tapping test. The sensor is immune to mechanical stress under the condition of 10⁴ taps with the strength of 1 MPa. A multilayer passivation film consisting SiN under polyimide film provides protection against contamination such as water. Thus, under USPCT conditions of 130°C, 80% humidity, and 48 h, the chips were not degraded. The tests confirm that the proposed sensor has sufficient reliability for normal identification usage     

A Fully Digital Time-Domain Smart Temperature Sensor Realized With 140 FPGA Logic Elements

To explore the possibility of soft intellectual property implementation, a fully digital smart temperature sensor without any full-custom device is proposed for painless VLSI or system-on-chip integrations. The signal is processed thoroughly in time domain instead of conventional voltage or current domain. A cyclic delay line is used to generate the pulse with a temperature-proportional width. The timing reference is just the input clock and a counter instead of voltage or current analog-to-digital converter is utilized for digital output coding. The circuit was implemented by field-programmable gate array chips for functionality verification and performance evaluation. Realized with as few as 140 logic elements, the proposed smart sensor was measured to have an error of -1.5 ~ 0.8 degC over the full commercial IC temperature operation range of 0 degC-75 degC for thermal self-sensing or monitoring. The effective resolution can be made better than 0.1 degC easily, and the power consumption is 8.42 muW at a sampling rate of 2 samples/s. The longest conversion time is around 260 s, and a conversion rate of 3 kHz at least is promised.     

手机液晶显示屏色温矫正

为了改善手机液晶显示屏白画面主观偏色的问题,本文运用了色度分析仪测量系统,对手机液晶显示屏白画面偏色矫正方法进行了研究。首先,分析了影响手机液晶显示屏白画面偏色的主要的原因,基于成本的考量,只进行后期模组段的色温矫正,借助设备厂商的色度分析仪测量手机液晶显示屏出厂时的白点坐标的分布范围,对比分析了色坐标优先(方案一)和亮度优先(方案二)两种色温矫正的方法。实验结果表明:方案一可以做到色坐标公差在±0.01以内,甚至更小(看算法的需要和设备的精度),但是无法应用于工程生产领域。方案二虽然牺牲了色温的一致性(±0.015),工厂的生产效率相比方案一提高了两倍多。综合考量成本和工厂生产效率的因素,方案二更好地满足了实际工程应用的需求。     

CMOS sensors for on-line thermal monitoring of VLSI circuits

The paper presents appropriate sensors for the realization of the design principle of design for thermal testability (DfTT). After a short overview of the available CMOS temperature sensors, a new family of temperature sensors will be presented, developed by the authors especially for the purpose of thermal monitoring of VLSI chips. These sensors are characterized by the very low silicon area of about 0.003-0.02 mm² and the low power consumption (200 μW). The accuracy is in the order of 1°C. Using the frequency-output versions an easy interfacing of digital test circuitry is assured. They can be very easily incorporated into the usual test circuitry, via the boundary-scan architecture. The paper presents measured results obtained by the experimental circuits. The facilities provided by the sensor connected to the boundary-scan test circuitry are also demonstrated experimentally     

A low noise, high resolution silicon temperature sensor

High resolution temperature measurement is essential for determination of blood perfusion in biomaterials. A compact, low noise, high resolution temperature sensor designed for use in an invasive tissue property measurement probe is presented. The circuit is based on traditional proportional-to-absolute-temperature (PTAT) principles. A feedback technique is used to improve linearity and reduce noise. Data from test chips shows temperature resolution of 3 m°C. The chips were fabricated using a 1.75 μm double poly, single metal modified CMOS process designed for this project     

The forward voltage technique to measure junction temperatures of ac operating triacs

The forward voltage drop Vfof an ac operating triac can be employed to indicate its junction temperature. The Vf, for a constant test current, is shown to decrease linearly with increasing temperature over the range of 20 to 125°C with measured slopes between -1.4 to -1.6 mV/°C. A sampling current must be used at the end of an applied power pulse and the cooling of the triac which takes place during the delay in measurement is taken into account by an extrapolation procedure. The indicated temperature using the Vfmethod is in excellent agreement With the maximum temperature measured with an infrared microradiometer at the surface of the active region of the triac. The Vftechnique requires a special power test circuit which is described. This technique provides an accurate indication of the maximum operating temperature and requires calibration of only a few triacs. Triac manufacturers can use the Vftechnique to accurately measure the thermal performance of their triacs and to screen production to eliminate marginal devices.