【作者】 梁坚；

【导师】 冯全源；

【作者基本信息】 西南交通大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 大规模集成电路的飞速发展使得电子产品的体积越来越小，促使了便携式电子产品如雨后春笋一般蓬勃发展，不断添加的新特征和能力，使得电子产品变得越来越复杂，作为电子设备运作的核心——电源就面临了越来越大的挑战。DC-DC电源管理芯片的高效率，低功耗等特性使得它在便携式电子设备市场中具有不可替代的地位，因此研究并改善DC-DC的性能具有很大的意义。除了性能要满足供电产品的要求外，电源自身的保护措施也非常重要，过流保护即是防止DC-DC因过载或输出短路造成意外损坏的防护措施之一。而电流检测又是过流保护的重中之重。本文中首先分析了传统电流检测方法的功能及优缺点，在此基础上研究并提出了一种适用于电流控制模式的降压型DC-DC芯片的高性能的电流检测电路，可以及时探知电流大小，可靠地保护芯片。本文所设计的电流检测电路包括电流采样电路和限流电路两部分，其中，电流采样部分是检测电路可靠工作的关键所在。电流采样是利用了差分放大器两个输入端的虚短特性，将一端与功率元件连接，则另一端输入就等于相应点的电压。采样电路使用了折叠式共源共栅差分电路作为采样放大器。并使用伸缩式串接差分电路构成两级比较器对采样信号进行比较。利用CMOS工艺设计的电路容易缩减元件尺寸，增加MOSFETs的速度，而且功耗低、制作成本也低，本文的电流检测电路就采用了0.6μm的标准CMOS工艺设计，达到了较好的性能指标。利用Hspice仿真，证明了该电流检测电路的可行性和可靠性。而且此电路也适用于升压型和降—升压型DC-DC芯片的电流检测。更多还原

【Abstract】 The rapid development of the large-scale integration (LSI) brings forth the increasingly smaller electronics, which in turn accelerates the flourishing of portable electronics. Meanwhile the growing new features and capacities make electronics more and more complex, and this poses even greater challenges to power supply, which serves as the core of the operation of electronics. The DC-DC converters, characterized by high efficiency and low power, have won an irreplaceable position in the electronics market. Thus it is of great significance to try to study and improve the performance of DC-DC converters.Apart from satisfying the requirements of power supply products, power supplies have to be protected in each and every way. Among all the protection measures, over-current protection is one of the most desirable one for many DC-DC converters against the accidental damages as a result of overload or short circuit. And current detecting is the key of over-current protection. After analyzing the advantages and disadvantages of the traditional detecting measures, this paper proposes to work out a current detecting circuit of high performance and suitable for the BUCK DC-DC converter in current-control-mode in order that it could detect the current in time and protect the chip effectively.The first part of this paper introduces the background and significance of this research; the second part comes to discuss some kinds of current sensing circuits. After that, on the basis of the prior knowledge, we successfully scheme out an over-current protection circuit which includes a current sensing circuit and a current limiting circuit. The principle of current sensing is as follows: if one input of differential amplifier is connected to power elements, the input voltage at the other end would be equal to that at the matching point. This paper uses a folded cascade operational amplifier for current sensing, and a telescopic cascade operational amplifier for current limiting.Circuits designed by CMOS technology have their competitive advantages-even smaller element size, faster speed of MOSFETs, low power consumption and low cost. So this circuit is manufactured by normal 0.6μm CMOS technology. The Hspice simulation results proved the feasibility and reliability of the circuit. And finally this circuit can also be used in the current detecting of the BOOST DC-DC converter and BUCK-BOOST DC-DC converter.更多还原