目前常用的大多数A/D转换器是单一正极性的,不能做负极性转换,因此需在转换前对信号进行变换.本文介绍用一个廉价的741集成运算放大器(对应于国产型号为F007)便可完成信号变换,使单极性的A/D转换器用作双极性转换,应用极为方便.1.差分放大器法运算放大器741是一双列直插式集成电路块,将其按图1方式接成一差分放大器.图1是一基本差分运算放大器,它是由741和4支匹配电阻组成.若两个输入信号为V_1和V_2,则差模信号为 Most commonly used A / D converter is a single positive polarity, can not do negative polarity conversion, so the signal conversion before conversion.This article describes the use of an inexpensive 741 integrated operational amplifier (corresponding to the domestic model F007) Can complete the signal conversion, so that unipolar A / D converter bipolar conversion, the application is extremely convenient. 1. Differential amplifier method Operational amplifier 741 is a dual in-line integrated circuit block, according to Figure 1 Figure 1 is a basic differential op amp which is composed of 741 and 4 matching resistors If the two input signals V_1 and V_2, the differential mode signal is