基于片上ADC/DAC实现精度可调ADC的方法

Method of adjustable precision ADC based on ADC and DAC

在数据采集系统中,由于成本限制和系统其他模块功能要求,系统中MCU的ADC精度有时无法满足系统测量精度要求。基于上述原因,提出一种利用MCU自带的10位ADC和DAC,结合运放、电容、电阻等元件搭建的外围硬件电路,实现将MCU自带的ADC转换为精度可调的ADC。软件设计是通过校正方法减小由硬件导致的ADC测量误差。实验结果表明,该系统可实现10～20位精度可调的ADC,测量精度最高可提高1 024倍,能够满足大多数情况下的测量精度要求。

In the data acquisition system, because of the limit of cost and the requirement of other modules in the system, the ADC precision of the MCU used can not meet the requirement of the measuring accuracy. As a result, this paper provides a method which makes use of ADC and DAC of MCU in combination with ordinary components such as operational amplifier, capacitance and resistance to set up the auxiliary circuit, and further converts the 10 digit ADC into an adjustable ADC with a high precision. This method can decrease the ADC measurement error caused by the error of parameter through the way of software calibration. The experiment results indicate that this system can achieve ADC with adjustable precision of 10-20 digit and the measurement precision can increase by 1024 times, so that it can meet the requirement of measwring accuracy in most cases.