请问纹波问题

我现在的直流模块输出纹波太大,测试发现高频(图2)低频纹波(图1)都有,请高手帮看看怎么改进阿?图3为没有上电时测试的结果,也发现有50K的高频,感觉好奇怪啊.我模块的开关频率为50K和100K.
谢谢!
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