AD转换器选用美国AD公司的AD574A，它是一种高性能的12位逐次逼进式A/D转换器，它的主要参数为： ①转换时间为25μs，线性误差为±1/2LSB-AD converter selection of U.S. AD AD574A, it is a high performance 12-bit successive pressing in the A/D converter, and its main parameters are: ① conversion time of 25μ