一、前言目前,由于数字技术和数字器件的迅速发展,因而,无论是在科学研究上,还是在工农业生产方面,都得到了广泛的应用。特别是对于某些精度要求较高的系统,为了满足系统的性能要求,往往使用这一技术来提高信号检测和信号变换的灵敏度和精度。另一方面,在一些数字、模拟混合系统中外面输入的信号为数字信号,后面各环节的工作信号又变为模拟信号,因而,往往使用这一技术,将数字变换成模拟信号,供系统中各环节使用。现在,我们所谈的小功率随动系统就属于这类情况。它的输入是数字量,而系统中其它各环节又工作于模拟信号之 I. Preface At present, due to the rapid development of digital technology and digital devices, it has been widely applied both in scientific research and in industrial and agricultural production. Especially for some systems with higher precision, it is often used to improve the sensitivity and accuracy of signal detection and signal conversion in order to meet the performance requirements of the system. On the other hand, in some digital and analog hybrid systems, the signals input from the outside are digital signals, and the signals from the following links become analog signals. Therefore, it is often used to transform the digital signals into analog signals for use in the system Each link use. Now, we talk about the low-power subsystems belong to this type of situation. Its input is digital, and the rest of the system works on analog signals