集成式斜波产生与求和电路的设计实现

针对电流模式控制DC/DC变换器固有的不稳定性,提出集斜波信号产生与求和为一体的斜波补偿电路.与传统的斜波产生与求和分离实现的补偿电路相比,该电路基于电容的电荷转移特性,将电流采样信号加在电容的下极板,对电容进行周期性充放电,在上极板实现斜波信号和电流采样信号的叠加.采用该电路不仅可以保证系统的稳定性,而且结构简单,易于实现；结合新的电流限结构,可以消除斜波补偿对最大电感电流的影响.电路基于0-35 μm CMOS工艺设计,仿真和测试结果表明：集成式斜波补偿电路功能正常,性能良好.当输出占空比在15％～80％变化时,峰值电感电流最大值的相对变化量小于5.5%．

Design and implementation of integration slope generation and summing circuit

A slope compensation circuit which combines the generation and summation of the slope signal was proposed in allusion to the instability of current mode control direct current/direct current (DC/DC) converter. Compared with the traditional compensation method which separates the slope compensation generation and summation, the proposed structure was based on the charge transfer characteristics of the capacitor. With the introduction of the sampling current signal added on the bottom of the capacitor which is charged and discharged periodically by the current, the summing of slope compensation and sampling current signal implemented on the top plate of the capacitor is realized. The presented slope compensation circuit can ensure the stability of the system, and is simple and easily to be implemented. In combination with the novel current limit circuit, the slope compensation effect on the maximum inductor current is eliminated. Based on the 0.35 μm complementary metal oxide semiconductor (CMOS) process, the simulation and test results show that the integration slope compensation circuit has correct functions and good performance. The relative variation of maximum inductor current was less than 5.5% with output duty cycle ranging from 15% to 80%．