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基于近红外(near-infrared,NIR)光谱,提出一种血液酒精的检测方法,并设计一种低噪声、低漂移、高精度的前置预放大电路,该电路用于准确检测血液中酒精的体积分数。在本设计电路中的电流电压转化部分,选择使用2种电路对比的方法,通过Multisim电路仿真软件模拟来比较电路的漂移和误差,同时利用Matlab进行数据处理;预放大电路部分利用高共模抑制比的AD620设计了差分放大电路,来提高电路的共模抑制比(common mode rejection ratio,CMRR)。结果表明,使用对称补偿型低温漂电流电压变换电路,能够很好的抑制漂移降低误差,与常用的OP07电流电压转换电路相比,可降低误差约2%,可降低漂移约97%,为微弱信号的处理提供了依据。
Based on near-infrared (NIR) spectroscopy, a method for the detection of blood alcohol is proposed and a low-noise, low-drift, high-precision pre-amplifier circuit is designed to accurately detect the presence of alcohol Volume fraction. In the design of the current circuit voltage conversion part, choose to use two kinds of circuit contrast method, through the Multisim simulation software to simulate the circuit to compare the drift and error, while using Matlab for data processing; Preamplifier circuit part of the use of high common-mode rejection The AD620 is designed with a differential amplifier circuit to increase the common mode rejection ratio (CMRR) of the circuit. The results show that using the symmetrical compensated low temperature drift current-voltage conversion circuit can well suppress the drift reduction error. Compared with the common OP07 current-voltage conversion circuit, the error can be reduced by about 2%, the drift can be reduced by 97% and the faint Signal processing provided the basis.