线性稳压电源电路振荡问题探究  

Study on the oscillation of the linear regulated power supply

作　　者：许超 焦新泉[1,2] 贾兴中[1,2] XU Chao;JIAO Xinquan;JIA Xingzhong(National Key Laboratory of Electronic Measurement Technology,North University of China,Taiyuan 030051,China;Key Laboratory of Instrument Science and Dynamic Testing,Ministry of Education,Taiyuan 030051,China)

机构地区：[1]中北大学电子测试技术国家重点实验室,山西太原030051 [2]仪器科学与动态测试教育部重点实验室,山西太原030051

出　　处：《电子设计工程》2021年第6期189-193,共5页Electronic Design Engineering

摘　　要：针对MIC29302电源芯片在超低压差线性稳压电路应用中设计有输出补偿电容时仍然出现振荡的问题,通过建立等效小信号数学模型并绘制bode图,深入剖析了振荡产生的原因。即补偿电容引入的零点与系统的第二主极点之间相差两个十倍频程,导致补偿零点未能有效补偿第二主极点的相位裕度,从而提出增加前馈补偿电容引入新的零点或调整输出电容容值改变零点频率两种解决方案,并进行了实验验证。实验结果表明,两种方案都能较好解决自激振荡问题。Aiming at the problem that the MIC29302 power chip still has oscillation when the output compensation capacitor is designed in the application of the ultra⁃low dropout linear voltage regulator circuit,by establishing an equivalent small signal mathematical model and drawing a bode diagram,the cause of the oscillation is analyzed in depth.The difference between the zero introduced by the compensation capacitor and the second main pole of the system is two octave bands,which causes the compensation zero to fail to effectively compensate the phase margin of the second main pole.There are two solutions to adjust the output capacitor capacitance to change the zero frequency,and the experiments are verified.The experimental results show that both schemes can better solve the problem of self⁃excited oscillation.

关 键 词：电路振荡 频率补偿 相位裕度 BODE图 零极点 前馈补偿 

分 类 号：TN751[电子电信—电路与系统]