双积分型V-T转换器的参数界定  

Parameter Definition of Double Integral V-T Converter

作　　者：宁新宁 郭红英 田竹梅 NING Xinning;GUO Hongying;TIAN Zhumei(Department of Electronics,Xinzhou Teachers University,Xinzhou,Shanxi 034000,China)

机构地区：[1]忻州师范学院电子系,山西忻州034000

出　　处：《宜宾学院学报》2021年第6期27-33,45,共8页Journal of Yibin University

基　　金：国家自然科学基金项目(11604304);忻州师范学院教学改革创新项目(JG201818)。

摘　　要：针对双积分型V-T转换器实际使用时因参数设置不当,在电压取值变化时,容易出现模拟电压信号转换输出脉冲计数的转换误差较大这一问题,以ICL7135为例,根据V-T转换器时钟信号对计数精度的影响以及高频率振荡电路对电路要求较高的条件,确定时钟信号频率范围为30 kHz~200 kHz.在时钟信号频率范围内对其他参数进行界定.由积分电容C3和积分电阻R1对积分过程的约束关系,界定积分电容C3的取值为0.22μF~1.5μF,典型值为0.47μF;积分电阻R1取值界定为51 kΩ~390 kΩ,典型值为100 kΩ.根据正向积分电流小于10 pA,积分电阻R1和限流电路R2影响积分电流的约束关系,R2参数界定为5.1 kΩ~500 kΩ,典型值为100 kΩ.自动归零电容C4容量越大噪声越小,器件尺寸越大噪声越大,参考电容C1容量越大杂散电容越小,以及常见电容的可获取性,C4取值为0.1μF~10μF,典型值为1μF,C1取值为0.1μF~10μF,典型值为1μF.实际使用时,C1、C3、C4取用聚丙烯电容,精度很高.在界定的参数范围任取三组数值,在0~+2 V输入模拟电压范围进行实验验证,结果证明,整体转换准确度符合要求,最大误差仅为0.2%,如果输入模拟电压变化范围较小,通过合适取值,可获得完全准确的转换结果.不同型号双积分型V-T转换器工作原理相同,器件参数功能相同,实际中取值不同,对转换精度具有类似的影响,ICL7135实验结论对其他双积分型V-T转换器具有借鉴意义.In view of the problem that the conversion error of analog voltage signal conversion output pulse count is large when the voltage value changes due to the improper parameter setting in the actual use of double integral V-T converter,taking ICL7135 as an example,according to the influence of V-T converter clock signal on count accuracy and the condition of high frequency oscillation circuit requiring high circuit requirements,the clock signal frequency range is determined as 30 kHz~200 kHz.Other parameters are defined in the frequency range of clock signal.According to the constraint relationship between inte⁃gral capacitance C3 and integral resistance R1,the value of integral capacitance C3 is defined as 0.22μF~1.5μF,and the typical value is 0.47μF;the value of integral resistance R1 is defined as 51 kΩ~390 kΩ,and the typical value is 100 kΩ.According to the constraint relationship between integral resistance R1 and current limiting circuit R2,the R2 parameter is defined as 5.1 kΩ~500 kΩ,and the typical value is 100 kΩ.The larger the capacity of automatic return to zero capacitor C4,the smaller the noise,the larger the size of the device,the larger the capacity of reference capacitor C1,the smaller the stray capacitance,and the avail⁃ability of common capacitors,C4 is 0.1μF~10μF,the typical value is 1μF,C1 is 0.1μF~10μF,the typical value is 1μF.In practical use,C1,C3 and C4 are polypropylene capacitors with high accuracy.Three groups of values are selected in the defined pa⁃rameter range,and the experimental verification is carried out in the range of 0~+2 V input analog voltage.The results show that the overall conversion accuracy meets the requirements,and the maximum error is only 0.2%.If the input analog voltage changes in a small range,through the appropriate value,complete and accurate conversion results can be obtained.Different mod⁃els of double integral V-T converters have the same working principle,the same device parameters and functions,and differentvalues in practice,which have

关 键 词：ICL7135 参数界定 转换准确度 电压 脉冲计数 

分 类 号：TP79[自动化与计算机技术—检测技术与自动化装置]