电流模式控制的DC-DC变换器中电流环的设计  

Analysis and Design of Current Sensing Circuit for Switching Converters

作　　者：刘颖杰[1] 冯全源[1] 

机构地区：[1]西南交通大学微电子研究所,四川成都610031

出　　处：《微电子学与计算机》2010年第7期25-30,共6页Microelectronics & Computer

基　　金：国家自然科学基金项目(10876029)

摘　　要：电流反馈环路是开关变换器中重要的模块之一,主要分析了常用的SENSEFET技术的不足,提出了一种优于SENSEFET技术的电流检测电路.该电路通过检测功率管上的压降反应电感电流的变化,利用工作在线性区的PMOS管代替电阻,采用体偏置跨导增大环路增益,提高检测精度,使输出检测电流与电感电流的比率几乎不受温度,工艺,电源电压等因素的影响.同时设计了一种自适应斜坡补偿电路,可根据输入,输出电压自动调节补偿斜率,有效解决了传统固定斜率斜坡补偿所产生的带载能力降低的问题.电路的输入电压范围为2.5～5.5V,工作频率为1MHz,可精确检测0～3.5A的电感电流,适用于大电流的开关变换器.Current loop circuit is one of the most important blocks in the current mode control DC-DC converters. The disadvantage of SENSEFET technique is analyzed and a novel current sensing circuit is proposed. The circuit can sense the inductor current through sensing the voltage across the power transistor. The sense ratio is hardly affected by temperature,process and supply voltage by using PMOS operated in linear region instead of resistance. The accuracy is enhanced by using body transconductance. Moreover,an adaptive slope compensation circuit which is able to adjust the slope according to the input and output voltage is presented. And the problem of over compensation is solved. The supply voltage range is 2.5～5.5V,work frequency is 1MHz. The proposed circuit can sense the inductor current changing from 0～3.5A accurately,and is suitable for high load current switching converter application.

关 键 词：开关变换器 电流检测 环路增益 斜坡补偿 

分 类 号：TN431.1[电子电信—微电子学与固体电子学]