基于复合热敏电阻材料的温补衰减器

发布时间：2018-01-09 03:02

本文关键词：基于复合热敏电阻材料的温补衰减器　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：在现代微波通信领域,低噪放(LNA)和功放(PA)系统的增益、输出功率和电压驻波比等主要射频指标随温度变化而变化。一般而言,当温度越高/越低时,系统的输出功率及增益将会越小/越大,则系统的输出功率及增益将随温度变化,导致系统指标受到严重影响。因此需要在射频系统中加入一种温度补偿的元件,即温补衰减器。温补衰减器通过电阻性厚膜材料来吸收功率从而转化为热量以实现衰减。当温度升高/降低时,温补衰减器的衰减量将减少/增大,补偿高频放大电路中增益随温度变化而减小/增大的特性。为实现更好的温度补偿特性,需要通过二种不同热敏特性的电阻的复合来设计温补衰减器。本论文从材料研制、器件仿真设计以及器件的制备与测试方面,主要做了以下三方面的工作来探索基于复合热敏电阻材料的温补衰减器的研究。材料研制方面,首先研究了NTC电阻LSMO材料的性能,测得其电阻平均膜厚为13.5μm,室温(25℃)电阻率为0.249Ω?cm,在-20℃~+120℃温度范围内,TCR为-2839.11 ppm/℃;在10℃~+120℃范围内,TCR达到-3602.3 ppm/℃,并对其进行了SEM测试和分析。然后掺杂0.05%-0.5%几个不同比例的Y2O3到BST材料中,研究钛酸钡系PTC电阻材料的性能。在-20℃~+120℃的温度范围内,掺Y的BST材料的电阻值基本随温度升高而增大,呈现出PTC电阻特性。在一定掺杂浓度下,电阻材料的室温电阻率与掺杂浓度存在U型曲线关系。对于掺杂Y0.0045的BST圆片样品,保温30 min时,样品有最低室温电阻率,为7.58kΩ?cm,TCR为6.34×104 ppm/℃;当保温60 min时,室温电阻率为13 kΩ?cm,TCR为1.24×105 ppm/℃,并对样品进行了XRD及SEM测试和分析。温补衰减器的设计方面,根据π型衰减器模型,通过热敏电阻的并联思想,采用不同输入输出端口形状的50Ω阻抗匹配,利用HFSS仿真软件设计了室温衰减量为-7 dB的,单段连续、二段不连续、三段不连续的三种不同输入输出端口模型的π型温补衰减器。温补衰减器的制备与测试方面,通过丝印工艺,将NTC和PTC电阻通过网版印刷在氧化铝基片上,并制作了测试用夹具,然后利用矢网和高低温箱测试其微波性能。其中三种模型的工作频率分别为:DC-3 GHz、DC-4 GHz、DC-6 GHz,在该频率范围内,其VSWR均小于2,S11均小于-10 dB。在-20℃~+85℃的温度范围内,三者的衰减量变化量均为1.25 dB左右,衰减量变化率为-0.0017dB/dB/℃左右。对三种模型都加载了一小时的功率测试,其承载功率大小为2 W,测得厚膜电阻表面最高温度均低于100℃,低于极限温度125℃,符合设计要求。
[Abstract]:In modern microwave communication field, low noise amplifier (LNA) and power amplifier (PA) gain of the system, the main indicators of RF output power and voltage in Bobbi with temperature changes. In general, when the temperature is higher / lower, the output power and gain system will be smaller / larger output power. And gain system will change with temperature, causing the system index has been seriously affected. Therefore need to add a temperature compensation in RF system components, namely temperature compensated attenuator. Temperature compensated attenuator by resistive thick film material to absorb power is transformed into heat to achieve attenuation. When the temperature increase / decrease, the decrement of temperature fill the attenuator will reduce / increase compensation for high frequency amplifier circuit gain change with temperature decreasing / increased characteristics. To realize temperature compensation characteristics better, through two different thermal properties of the composite design of temperature resistance Fill the attenuator. In this thesis, material design, fabrication and testing device design and simulation device system, mainly from the following three aspects to study composite thermistor material temperature compensated attenuator. Based on material research, firstly studies the performance of the NTC resistance of LSMO material, measured the resistance of average film thickness 13.5 m, at room temperature (25 DEG C) resistivity 0.249? Cm, -20 at ~+120 DEG C temperature range of TCR to -2839.11 ppm/ at 10 DEG ~+120 DEG C; in the range of TCR to -3602.3, ppm/ C, and has carried on the SEM test and analysis. Then several different proportion of Y2O3 doped 0.05%-0.5% to BST materials, properties of barium titanate PTC resistance material. The temperature range of -20 DEG ~+120 DEG C, the resistance of Y doped BST material value increases with the temperature rise, showing a PTC resistance. In a certain doping concentration, resistance at room temperature There is U shape relationship between resistivity and doping concentration for BST wafer samples doped with Y0.0045, holding 30 min, samples have the lowest resistivity at room temperature, 7.58k. Cm, TCR? 6.34 x 104 ppm/ C; when the insulation of 60 min, the room temperature resistivity of 13 K cm, TCR 1.24 Omega? * 105 ppm/ C, the samples were tested by XRD and SEM test and analysis. The design of temperature compensated attenuator, PI type attenuator according to the model, the idea of parallel thermistor, matching with 50 ohm impedance different input and output port shape, using the HFSS simulation software design of room temperature attenuation of -7 dB, a single continuous. The two section is not continuous, PI Wen three discontinuous segments of three different input and output port model complement attenuator. Preparation and testing temperature compensated attenuator system, through the screen printing process, NTC and PTC resistance by screen printing on alumina substrates, and made the test fixture, however After the use of vector network and low temperature test box. The working frequency of the microwave absorption properties of three kinds of models are: DC-3 GHz, DC-4 GHz, DC-6 GHz, in the frequency range, the VSWR were less than 2, S11 less than -10 dB. in the temperature range of -20 DEG ~+85 DEG C, the attenuation variation three who was about 1.25 dB, the attenuation rate is -0.0017dB/dB/ degrees Celsius. The three models are loaded with power one hour test, the power load size is 2 W, the measured maximum temperature of the surface of the thick film resistor are lower than 100 DEG C, below a critical temperature of 125 DEG C, meet the design requirements.

【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN715

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