血液酒精的近红外光谱法检测预放大电路设计

Design of pre-amplifier circuit on blood alcohol detection based on NIR

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。

A blood alcohol detection method was investigated based on NIR（near-infrared） spectroscopy.And a low-noise, low-drift and high-precision preamplifier was designed to detect the blood alcohol volume fraction accurately.In the current-voltage conversion section, the simulation of drift and error of two kinds of circuits were carried out by Multisim software.AD620 was selected in the preamplifier part which could improve the CMRR（common mode rejection ratio） of circuits.The results of simulation showed that the current-voltage conversion circuit of symmetrical compensa-tional low-temperature drift can suppressed the drift and reduced error better.Compared with the OP07 current-voltage conversion circuit, the error could be reduced by 2%, while the draft could be reduced by 97%, which could support weak signal analyzing.