一、引言众所周知,在工业微机控制系统中,通常都必须应用模—数转换器(A/D)。但是,考虑到实际测量中常用的压力、温度等一次传感器,由于其输出仅为数毫伏到数十毫伏数量级的模拟电医信号,若采用目前市售的常规A/D集成片,就必须另加一只毫伏放大器和多路开关。这样,A/D集成片本身的多路开关实际上只能利用一路,这显然是不经济的。另外,若要使整个系统达到1％的精度,在选择精度为1％的传感器的同时,通常还必须使毫伏放 I. Introduction As we all know, in the industrial computer control system, usually must use analog-digital converter (A / D). However, taking into account the commonly used in the actual measurement of pressure, temperature and other sensors, because the output is only a few millivolts to tens of mV order analog electrical signals, the use of the current market conventional A / D chip, you must Plus a millivolt amplifier and multiplexer. In this way, A / D chip itself multiplexer can actually use only one way, which is obviously not economical. In addition, to achieve a 1% accuracy of the overall system, it is often necessary to have a millivolt