基于ADG1607十六通道湿度测量电路设计

Design of Sixteen-channel Humidity Measuring Circuit Based on ADG1607

为了解决多路湿度测量各个通道系统误差一致性以及简化ADC电路的问题,采用两片ADG1607电子模拟开关和一片AD7792数模转换器构成信号测量电路,通过MCU控制模拟开关阵列进行切换,实现十六路湿度模拟信号的采集,按照预设的顺序分时送入AD转换为数字量输出,通道切换需要稳定时间,经验值采取10 ms;在输入电路加入合适的电阻和电容组成RC滤波电路消除开关切换带来一些毛刺干扰,同时引入正确的放电回路,防止电荷积累而影响测量精度;对电路进行测试,结果表明,各通道之间最大误差为0.17%,通道一致性评价为,相对误差0.003,平均绝对离差0.002475,标准差为0.095;该电路已经在实际的自动气象站中长期应用,无机械触点的模拟电子开关能够很好地适应频繁切换,其整体测量性能指标满足气象观测设备对湿度测量准确度的要求。

In order to solve the problem of system error consistency for each channel of multi-channel humidity measurement and to simplify the ADC circuit,two ADG1607 electronic analog switches and one AD7792 digital-to-analog converter(DAC)are used to form the signal measurement circuit,and the analog switch array is controlled by MCU to switch the signals,so the collection of sixteen-channel humidity analog signals is realized.According to the preset sequence in time,the analog signals are converted into the digital signals by the electronic analog switches and DAC,the channel switching needs the stable time,and the empirical value is selected by10 ms.The appropriate resistance and capacitance of the input circuit are added to form the RC filter circuit,and eliminate some burr interference caused by the switch-switching,and the correct discharge circuit is introduced to prevent the charge accumulation from affecting the measurement accuracy.By the circuit test,the results show that the maximum error of each channel reaches by 0.17%,the relative error by 0.003,the average absolute deviation by 0.002475,and the standard deviation by 0.095.The analog electronic switch of the circuit can well meet the necessity of frequently switching,and can satisfy the requirements of humidity measurement accuracy for meteorological observation equipment.