目前市场上常见的8位A/D器件的精度在某些场合不能满足要求。而12位A/D器件比8位器件的价格贵十几倍。常用的程控放大器,浮点转换法虽然也可以提高精度,但由于控制程序及数据处理程序复杂,转换速度慢,电路调试困难等,使用不便。本文提出以一片8位A/D和一片8位D/A组成16位A/D转换单元。其最大转换时间为240μs(2倍ADC0809转换时间),且控制程序简单,所得数据为定点数形式。这就为处理数据提供了方便。 The accuracy of the 8-bit A / D devices commonly found on the market today can not meet the requirements in some cases. While 12-bit A / D devices are more than ten times more expensive than 8-bit devices. Commonly used program-controlled amplifiers, floating-point conversion method can improve accuracy, but because of the control program and data processing program is complex, slow conversion speed, circuit debugging difficulties, the use of inconvenience. This paper proposes to a 16-bit A / D conversion unit with a 8-bit A / D and a 8-bit D / A. The maximum conversion time of 240μs (2 times ADC0809 conversion time), and the control program is simple, the data obtained for the fixed-point number form. This provides the convenience of processing the data.